Editing MPEP 2163

<noinclude>{{MPEP Section|2162|2100|2164 }}</noinclude>

==[[MPEP 2163|2163 Guidelines for the Examination of Patent Applications Under the 35 U.S.C. 112, para. 1, "Written Description" Requirement]]==

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The following Guidelines establish the policies and 
procedures to be followed by Office personnel in the 
evaluation of any patent application for compliance 
with the written description requirement of 35 U.S.C. 
112. These Guidelines are based on the Office’s current 
understanding of the law and are believed to be 
fully consistent with binding precedent of the U.S. 
Supreme Court, as well as the U.S. Court of Appeals 
for the Federal Circuit and its predecessor courts. 

The Guidelines do not constitute substantive rulemaking 
and hence do not have the force and effect of 
law. They are designed to assist Office personnel in 
analyzing claimed subject matter for compliance with 
substantive law. Rejections will be based upon the 
substantive law, and it is these rejections which are 
appealable. Consequently, any perceived failure by 
Office personnel to follow these Guidelines is neither 
appealable nor petitionable.

These Guidelines are intended to form part of the 
normal examination process. Thus, where Office personnel 
establish a prima facie case of lack of written 
description for a claim, a thorough review of the prior 
art and examination on the merits for compliance with 
the other statutory requirements, including those of 
35 
U.S.C. 101, 102, 103, and 112, is to be conducted 
prior to completing an Office action which includes a 
rejection for lack of written description. 

I.GENERAL PRINCIPLES GOVERNING 
COMPLIANCE WITH THE “WRITTEN 
DESCRIPTION” REQUIREMENT FOR 
APPLICATIONS

 The first paragraph of 35 U.S.C. 112 requires that 
the “specification shall contain a written description 
of the invention   .” This requirement is separate 
and distinct from the enablement requirement. See, 
e.g., Vas-Cath, Inc. v. Mahurkar, 935 F.2d 1555, 1560, 
19 USPQ2d 1111, 1114 (Fed. Cir. 1991). See also 
Univ. of Rochester v. G.D. Searle & Co., 358 F.3d 916, 
920-23, 69 USPQ2d 1886, 1890-93 (Fed. Cir. 2004) 
(discussing history and purpose of the written description 
requirement); In re Curtis, 354 F.3d 1347, 1357, 
69 USPQ2d 1274, 1282 (Fed. Cir. 2004) (“conclusive 
evidence of a claim’s enablement is not equally conclusive 
of that claim’s satisfactory written description”). 
The written description requirement has 
several policy objectives. “[T]he ‘essential goal’ of 
the description of the invention requirement is to 
clearly convey the information that an applicant has 
invented the subject matter which is claimed.” In re 
Barker, 559 F.2d 588, 592 n.4, 194 USPQ 470, 473 
n.4 (CCPA 1977). Another objective is to put the public 
in possession of what the applicant claims as the 
invention. See Regents of the University of California 
v. Eli Lilly, 119 F.3d 1559, 1566, 43 USPQ2d 1398, 
1404 (Fed. Cir. 1997), cert. denied, 523 U.S. 1089 
(1998). “The ‘written description’ requirement 
implements the principle that a patent must describe 
the technology that is sought to be patented; the 
requirement serves both to satisfy the inventor’s obligation 
to disclose the technologic knowledge upon 
which the patent is based, and to demonstrate that the 
patentee was in possession of the invention that is 
claimed.” Capon v. Eshhar, 418 F.3d 1349, 1357, 76 
USPQ2d 1078, 1084 (Fed. Cir. 2005). Further, the
written description requirement  promotes the 
progress of the useful arts by ensuring that patentees 
adequately describe their inventions in their patent 
specifications in exchange for the right to exclude 
others from practicing the invention for the duration 
of the patent’s term.

To satisfy the written description requirement, a 
patent specification must describe the claimed invention 
in sufficient detail that one skilled in the art can 
reasonably conclude that the inventor had possession 
of the claimed invention. See, e.g., Moba, B.V. v. Diamond 
Automation, Inc., 325 F.3d 1306, 1319, 66 
USPQ2d 1429, 1438 (Fed. Cir. 2003); Vas-Cath, Inc. 
v. Mahurkar, 935 F.2d at 1563, 19 USPQ2d at 1116. 
However, a showing of possession alone does not cure 
the lack of a written description. Enzo Biochem, Inc. v. 
Gen-Probe, Inc., 323 F.3d 956, 969-70, 63 USPQ2d 
1609, 1617 (Fed. Cir. 2002). Much of the written 
description case law addresses whether the specification 
as originally filed supports claims not originally 
in the application. The issue raised in the cases is most 
often phrased as whether the original application provides 
“adequate support” for the claims at issue or 
whether the material added to the specification incorporates 
“new matter” in violation of 35 U.S.C. 132. 
The “written description” question similarly arises in 
the interference context, where the issue is whether 
the specification of one party to the interference can 
support the newly added claims corresponding to the 
count at issue, i.e., whether that party can “make the 
claim” corresponding to the interference count. See, 
e.g., Martin v. Mayer, 823 F.2d 500, 503, 3 
USPQ2d 
1333, 1335 (Fed. Cir. 1987). In addition, 





early opinions suggest the Patent and Trademark 
Office was unwilling to find written descriptive support 
when the only description was found in the 
claims; however, this viewpoint was rejected. See In 
re Koller, 613 F.2d 819, 204 USPQ 702 (CCPA 1980) 
(original claims constitute their own description); 
accord In re Gardner, 475 F.2d 1389, 177 USPQ 396 
(CCPA 1973); accord In re Wertheim, 541 F.2d 257, 
191 USPQ 90 (CCPA 1976). It is now well accepted 
that a satisfactory description may be in the claims or 
any other portion of the originally filed specification. 
These early opinions did not address the quality or 
specificity of particularity that was required in the 
description, i.e., how much description is enough. 

An applicant shows possession of the claimed 
invention by describing the claimed invention with all 
of its limitations using such descriptive means as 
words, structures, figures, diagrams, and formulas that 
fully set forth the claimed invention. Lockwood v. 
American Airlines, Inc., 107 F.3d 1565, 1572, 
41 
USPQ2d 1961, 1966 (Fed. Cir. 1997). Possession 
may be shown in a variety of ways including description 
of an actual reduction to practice, or by showing 
that the invention was “ready for patenting” such as 
by the disclosure of drawings or structural chemical 
formulas that show that the invention was complete, 
or by describing distinguishing identifying characteristics 
sufficient to show that the applicant was in possession 
of the claimed invention. See, e.g., Pfaff v. 
Wells Elecs., Inc., 525 U.S. 55, 68, 119 S.Ct. 304, 312, 
48 USPQ2d 1641, 1647 (1998); Eli Lilly, 119 F.3d at 
1568, 43 USPQ2d at 1406; Amgen, Inc. v. Chugai 
Pharmaceutical, 927 F.2d 1200, 1206, 18 
USPQ2d 
1016, 1021 (Fed. Cir. 1991) (one must define a compound 
by “whatever characteristics sufficiently distinguish 
it”). “Compliance with the written description 
requirement is essentially a fact-based inquiry that 
will ‘necessarily vary depending on the nature of the 
invention claimed.’” Enzo Biochem, 323 F.3d at 963, 
63 USPQ2d at 1613. An application specification may 
show actual reduction to practice by describing testing 
of the claimed invention or, in the case of biological 
materials, by specifically describing a deposit 
made in 
accordance with 37 CFR 1.801 et seq. See 
Enzo Biochem, 323 F.3d at 965, 63 USPQ2d at 1614 
(“reference in the specification to a deposit may also 
satisfy the written description requirement with 
respect to a claimed material”); see also Deposit of 
Biological Materials for Patent Purposes, Final Rule, 
54 FR 34,864 (August 22, 1989) (“The requirement 
for a specific identification is consistent with the 
description requirement of the first paragraph of 35 
U.S.C. 112, and to provide an antecedent basis for the 
biological material which either has been or will be 
deposited before the patent is granted.” Id. at 34,876. 
“The description must be sufficient to permit verification 
that the deposited biological material is in fact 
that disclosed. Once the patent issues, the description 
must be sufficient to aid in the resolution of questions 
of infringement.” Id. at 34,880.). Such a deposit is not 
a substitute for a written description of the claimed 
invention. The written description of the deposited 
material needs to be as complete as possible because 
the examination for patentability proceeds solely on 
the basis of the written description. See, e.g., In re 
Lundak, 773 F.2d 1216, 227 USPQ 90 (Fed. Cir. 
1985). See also 54 FR at 34,880 (“As a general rule, 
the more information that is provided about a particular 
deposited biological material, the better the examiner 
will be able to compare the identity and 
characteristics of the deposited biological material 
with the prior art.”).

A question as to whether a specification provides 
an adequate written description may arise in the context 
of an original claim which is not described sufficiently 
(see, e.g., LizardTech, Inc. v. Earth Resource 
Mapping, Inc., 424 F.3d 1336, 1345, 76 USPQ2d 
1724, 1733 (Fed. Cir. 2005); Enzo Biochem, 323 
F.3d at 968, 63 USPQ2d at 1616 (Fed. Cir. 2002); Eli 
Lilly, 119 F.3d 1559, 43 USPQ2d 1398), a new or 
amended claim wherein a claim limitation has been 
added or removed, or a claim to entitlement of an earlier 
priority date or effective filing date under 35 
U.S.C. 119, 120, or 365(c). Most typically, the issue 
will arise in the context of determining whether new 
or amended claims are supported by the description of 
the invention in the application as filed (see, e.g., In re 
Wright, 866 F.2d 422, 9 USPQ2d 1649 (Fed. Cir. 
1989)), whether a claimed invention is entitled to the 
benefit of an earlier priority date or effective filing 
date under 35 U.S.C. 119, 120, or 365(c) (see, e.g., 
New Railhead Mfg. L.L.C. v. Vermeer Mfg. Co., 298 
F.3d 1290, 63 USPQ2d 1843 (Fed. Cir. 2002); Tronzo 
v. Biomet, Inc., 156 F.3d 1154, 47 USPQ2d 1829 (Fed. 
Cir. 1998); Fiers v. Revel, 984 F.2d 1164, 25 USPQ2d 
1601 (Fed. Cir. 1993); In re Ziegler, 992 F.2d 1197, 





1200, 26 USPQ2d 1600, 1603 (Fed. Cir. 1993)), or 
whether a specification provides support for a claim 
corresponding to a count in an interference (see, e.g., 
Fields v. Conover, 443 F.2d 1386, 170 USPQ 276 
(CCPA 1971)). Compliance with the written description 
requirement is a question of fact which must be 
resolved on a case-by-case basis. Vas-Cath, Inc. v. 
Mahurkar, 935 F.2d at 1563, 19 USPQ2d at 1116 
(Fed. Cir. 1991).

A.Original Claims

There is a strong presumption that an adequate 
written description of the claimed invention is present 
when the application is filed. In re Wertheim, 541 F.2d 
257, 263, 191 USPQ 90, 97 (CCPA 1976) (“we are of 
the opinion that the PTO has the initial burden of presenting 
evidence or reasons why persons skilled in the 
art would not recognize in the disclosure a description 
of the invention defined by the claims”). However, as 
discussed in paragraph I., supra, the issue of a lack of 
adequate written description may arise even for an 
original claim when an aspect of the claimed invention 
has not been described with sufficient particularity 
such that one skilled in the art would recognize 
that the applicant had possession of the claimed 
invention. The claimed invention as a whole may not 
be adequately described if the claims require an 
essential or critical feature which is not adequately 
described in the specification and which is not conventional 
in the art or known to one of ordinary skill 
in the art. For example, consider the claim “A gene 
comprising SEQ ID NO:1.” A determination of what 
the claim as a whole covers may result in a conclusion 
that specific structures such as a promoter, a coding 
region, or other elements are included. Although all 
genes encompassed by this claim share the characteristic 
of comprising SEQ ID NO:1, there may be insufficient 
description of those specific structures (e.g., 
promoters, enhancers, coding regions, and other regulatory 
elements) which are also included. 

The claimed invention as a whole may not be adequately 
described where an invention is described 
solely in terms of a method of its making coupled 
with its function and there is no described or art-recognized 
correlation or relationship between the structure 
of the invention and its function. A biomolecule 
sequence described only by a functional characteristic, 
without any known or disclosed correlation 
between that function and the structure of the 
sequence, normally is not a sufficient identifying 
characteristic for written description purposes, even 
when accompanied by a method of obtaining the 
claimed sequence. For example, even though a 
genetic code table would correlate a known amino 
acid sequence with a genus of coding nucleic acids, 
the same table cannot predict the native, naturally 
occurring nucleic acid sequence of a naturally occurring 
mRNA or its corresponding cDNA. Cf. In re Bell, 
991 F.2d 781, 26 USPQ2d 1529 (Fed. Cir. 1993), and 
In re Deuel, 51 F.3d 1552, 34 USPQ2d 1210 (Fed. Cir. 
1995) (holding that a process could not render the 
product of that process obvious under 35 U.S.C. 103). 
The Federal Circuit has pointed out that under United 
States law, a description that does not render a 
claimed invention obvious cannot sufficiently 
describe the invention for the purposes of the written 
description requirement of 35 U.S.C. 112. Eli Lilly, 
119 F.3d at 1567, 43 USPQ2d at 1405. Compare 
Fonar Corp. v. General Electric Co., 107 F.3d 1543, 
1549, 41 USPQ2d 1801, 1805 (Fed. Cir. 1997) (“As a 
general rule, where software constitutes part of a best 
mode of carrying out an invention, description of such 
a best mode is satisfied by a disclosure of the functions 
of the software. This is because, normally, writing 
code for such software is within the skill of the art, 
not requiring undue experimentation, once its functions 
have been disclosed.    Thus, flow charts or 
source code listings are not a requirement for adequately 
disclosing the functions of software.”).

A lack of adequate written description issue also 
arises if the knowledge and level of skill in the art 
would not permit one skilled in the art to immediately 
envisage the product claimed from the disclosed process. 
See, e.g., Fujikawa v. Wattanasin, 93 F.3d 1559, 
1571, 39 USPQ2d 1895, 1905 (Fed. Cir. 1996) (a 
“laundry list” disclosure of every possible moiety 
does not constitute a written description of every species 
in a genus because it would not “reasonably lead” 
those skilled in the art to any particular species); In re 
Ruschig, 379 F.2d 990, 995, 154 USPQ 118, 123 
(CCPA 1967) (“If n-propylamine had been used in 
making the compound instead of n-butylamine, the 
compound of claim 13 would have resulted. Appellants 
submit to us, as they did to the board, an imaginary 
specific example patterned on specific example 6 
by which the above butyl compound is made so that 





we can see what a simple change would have resulted 
in a specific supporting disclosure being present in the 
present specification. The trouble is that there is no 
such disclosure, easy though it is to imagine it.”) 
(emphasis in original); Purdue Pharma L.P. v. Faulding 
Inc., 230 F.3d 1320, 1328, 56 USPQ2d 1481, 1487 
(Fed. Cir. 2000) (“the specification does not clearly 
disclose to the skilled artisan that the inventors ... considered 
the ratio... to be part of their invention .... 
There is therefore no force to Purdue’s argument that 
the written description requirement was satisfied 
because the disclosure revealed a broad invention 
from which the [later-filed] claims carved out a patentable 
portion”).

B.New or Amended Claims

The proscription against the introduction of new 
matter in a patent application (35 U.S.C. 132 and 251) 
serves to prevent an applicant from adding information 
that goes beyond the subject matter originally 
filed. See In re Rasmussen, 650 F.2d 1212, 1214, 211 
USPQ 323, 326 (CCPA 1981). See MPEP § 2163.06through § 2163.07 for a more detailed discussion of 
the written description requirement and its relationship 
to new matter. The claims as filed in the original 
specification are part of the disclosure and, therefore, 
if an application as originally filed contains a claim 
disclosing material not found in the remainder of the 
specification, the applicant may amend the specification 
to include the claimed subject matter. In re 
Benno, 768 F.2d 1340, 226 USPQ 683 (Fed. Cir. 
1985). Thus, the written description requirement prevents 
an applicant from claiming subject matter that 
was not adequately described in the specification as 
filed. New or amended claims which introduce elements 
or limitations which are not supported by the 
as-filed disclosure violate the written description 
requirement. See, e.g., In re Lukach, 442 F.2d 967, 
169 USPQ 795 (CCPA 1971) (subgenus range was 
not supported by generic disclosure and specific 
example within the subgenus range); In re Smith, 
458 
F.2d 1389, 1395, 173 USPQ 679, 683 (CCPA 
1972) (a subgenus is not necessarily described by a 
genus encompassing it and a species upon which it 
reads).

While there is no in haec verba requirement, newly 
added claim limitations must be supported in the 
specification through express, implicit, or 
inherent 
disclosure. An amendment to correct an 
obvious error does not constitute new matter where 
one skilled in the art would not only recognize 
the 
existence of the error in the specification, but also 
recognize the appropriate correction. In re Oda, 
443 
F.2d 1200, 170 
USPQ 268 (CCPA 1971). With 
respect to the correction of sequencing errors in applications 
disclosing nucleic acid and/or amino acid 
sequences, it is well known that sequencing errors are 
a common problem 
in molecular biology. See, e.g., 
Peter Richterich, Estimation of Errors in ‘Raw’ DNA 
Sequences: A Validation Study, 8 Genome Research251-59 (1998). If an application as filed includes 
sequence information and references a deposit of the 
sequenced material made in accordance with the 
requirements of 37 CFR 1.801 et seq., amendment 
may be permissible. Deposits made after the application 
filing date cannot be relied upon to support additions 
to or correction of information in the application 
as filed. Corrections of minor errors in the sequence 
may be possible based on the argument that one of 
skill in the art would have resequenced the deposited 
material and would have immediately recognized the 
minor error. Deposits made after the filing date can 
only be relied upon to provide support for the correction 
of sequence information if applicant submits a 
statement in compliance with 37 CFR 1.804 stating 
that the biological material which is deposited is a 
biological material specifically defined in the application 
as filed.

Under certain circumstances, omission of a limitation 
can raise an issue regarding whether the inventor 
had possession of a broader, more generic invention. 
See, e.g., PIN/NIP, Inc. v. Platte Chem. Co., 304 F.3d 
1235, 1248, 64 USPQ2d 1344, 1353 (Fed. Cir. 2002) 
(Claim for a method of inhibiting sprout growth on 
tubers by treating them with spaced, sequential application 
of two chemicals was held invalid for lack of 
adequate written description where the specification 
indicated that invention was a method of applying a 
“composition,” or mixture, of the two chemicals.); 
Gentry Gallery, Inc. v. Berkline Corp., 134 
F.3d 1473, 
45 USPQ2d 1498 (Fed. Cir. 1998) (claims to a sectional 
sofa comprising, inter alia, a console and a control 
means were held invalid for failing to satisfy the 
written description requirement where the claims 
were broadened by removing the location of the control 
means); Johnson Worldwide Associates v. Zebco 





Corp., 175 F.3d 985, 993, 50 
USPQ2d 1607, 1613 
(Fed. Cir. 1999) (In Gentry Gallery, the “court’s 
determination that the patent disclosure did not support 
a broad meaning for the disputed claim terms was 
premised on clear statements in the written description 
that described the location of a claim element--
the ‘control means’ --as ‘the only possible location’ 
and that variations were ‘outside the stated purpose of 
the invention.’ Gentry Gallery, 134 
F.3d at 1479, 45 
USPQ2d at 1503. Gentry Gallery, then, considers the 
situation where the patent’s disclosure makes crystal 
clear that a particular (i.e., narrow) understanding of a 
claim term is an ‘essential element of [the inventor’s] 
invention.’”); Tronzo v. Biomet, 156 F.3d at 1158-59, 
47 USPQ2d at 1833 (Fed. Cir. 1998) (claims to 
generic cup shape were not entitled to filing date of 
parent application which disclosed “conical cup” in 
view of the disclosure of the parent application stating 
the advantages and importance of the conical shape.). 
A claim that omits an element which applicant 
describes as an essential or critical feature of the 
invention originally disclosed does not comply with 
the written description requirement. See Gentry Gallery, 
134 F.3d at 1480, 45 
USPQ2d at 1503; In re Sus, 
306 F.2d 494, 504, 134 
USPQ 301, 309 (CCPA 1962) 
(“[O]ne skilled in this art would not be taught by the 
written description of the invention in the specification 
that any ‘aryl or substituted aryl radical’ would 
be suitable for the purposes of the invention but rather 
that only certain aryl radicals and certain specifically 
substituted aryl radicals [i.e., aryl azides] would be 
suitable for such purposes.”) (emphasis in original). A 
claim which omits matter disclosed to be essential to 
the invention as described in the specification or in 
other statements of record may also be subject to 
rejection under 35 
U.S.C. 112, para. 1, as not 
enabling, or under 35 
U.S.C. 112, para. 2. See In re 
Mayhew, 527 F.2d 1229, 188 USPQ 356 (CCPA 
1976); In re Venezia, 530 F.2d 956, 189 USPQ 149 
(CCPA 1976); and In re Collier, 397 F.2d 1003, 158 
USPQ 266 (CCPA 1968). See also MPEP § 2172.01.

The fundamental factual inquiry is whether the 
specification conveys with reasonable clarity to those 
skilled in the art that, as of the filing date sought, 
applicant was in possession of the invention as now 
claimed. See, e.g., Vas-Cath, Inc., 935 F.2d at 1563-
64, 19 USPQ2d at 1117.

II.METHODOLOGY FOR DETERMINING 
ADEQUACY OF WRITTEN DESCRIP-
TION

A.Read and Analyze the Specification for 
Compliance with 35 U.S.C. 112, para. 1

Office personnel should adhere to the following 
procedures when reviewing patent applications for 
compliance with the written description requirement 
of 35 U.S.C. 112, para. 1. The examiner has the initial 
burden, after a thorough reading and evaluation of the 
content of the application, of presenting evidence or 
reasons why a person skilled in the art would not recognize 
that the written description of the invention 
provides support for the claims. There is a strong presumption 
that an adequate written description of the 
claimed invention is present in the specification as 
filed, Wertheim, 541 F.2d at 262, 191 USPQ at 96; 
however, with respect to newly added or amended 
claims, applicant should show support in the original 
disclosure for the new or amended claims. See MPEP 
§ 714.02 and § 2163.06 (“Applicant should    specifically 
point out the support for any amendments 
made to the disclosure.”); and MPEP § 2163.04 (“If 
applicant amends the claims and points out where 
and/or how the originally filed disclosure supports the 
amendment(s), and the examiner finds that the disclosure 
does not reasonably convey that the inventor had 
possession of the subject matter of the amendment at 
the time of the filing of the application, the examiner 
has the initial burden of presenting evidence or reasoning 
to explain why persons skilled in the art would 
not recognize in the disclosure a description of the 
invention defined by the claims.”). Consequently, 
rejection of an original claim for lack of written 
description should be rare. The inquiry into whether 
the description requirement is met is a question of fact 
that must be determined on a case-by-case basis. See 
In re Smith, 458 F.2d 1389, 1395, 173 USPQ 679, 683 
(CCPA 1972) (“Precisely how close [to the claimed 
invention] the description must come to comply with 
Sec. 112 must be left to case-by-case development.”); 
In re Wertheim, 541 F.2d at 262, 191 USPQ at 96 
(inquiry is primarily factual and depends on the nature 
of the invention and the amount of knowledge 
imparted to those skilled in the art by the disclosure).





1.For Each Claim, Determine What the Claim 
as a Whole Covers

 Claim construction is an essential part of the examination 
process. Each claim must be separately analyzed 
and given its broadest reasonable interpretation 
in light of and consistent with the written description. 
See, e.g., In re Morris, 127 F.3d 1048, 1053-54, 
44 
USPQ2d 1023, 1027 (Fed. Cir. 1997). The entire 
claim must be considered, including the preamble language 
and the transitional phrase. “Preamble language” 
is that language in a claim appearing before 
the transitional phase, e.g., before “comprising,” 
“consisting essentially of,” or “consisting of.” The 
transitional term “comprising” (and other comparable 
terms, e.g., “containing,” and “including”) is “open-
ended” -it covers the expressly recited subject matter, 
alone or in combination with unrecited subject matter. 
See, e.g., Genentech, Inc. v. Chiron Corp., 112 F.3d 
495, 501, 42 USPQ2d 1608, 1613 (Fed. Cir. 1997) 
(“‘Comprising’ is a term of art used in claim language 
which means that the named elements are essential, 
but other elements may be added and still form a construct 
within the scope of the claim.”); Ex parte 
Davis, 80 USPQ 448, 450 (Bd. App. 1948) (“comprising” 
leaves the “claim open for the inclusion of 
unspecified ingredients even in major amounts”). See 
also MPEP § 2111.03. “By using the term ‘consisting 
essentially of,’ the drafter signals that the invention 
necessarily includes the listed ingredients and is open 
to unlisted ingredients that do not materially affect the 
basic and novel properties of the invention. A ‘consisting 
essentially of’ claim occupies a middle ground 
between closed claims that are written in a ‘consisting 
of’ format and fully open claims that are drafted in a 
‘comprising’ format.” PPG Industries v. Guardian 
Industries, 156 
F.3d 1351, 1354, 48 USPQ2d 1351, 
1353-54 (Fed. Cir. 1998). For the purposes of searching 
for and applying prior art under 35 U.S.C. 102 and 
103, absent a clear indication in the specification or 
claims of what the basic and novel characteristics 
actually are, “consisting essentially of” will be construed 
as equivalent to “comprising.” See, e.g., PPG, 
156 F.3d at 1355, 48 USPQ2d at 1355 (“PPG could 
have defined the scope of the phrase ‘consisting 
essentially of’ for purposes of its patent by making 
clear in its specification what it regarded as constituting 
a material change in the basic and novel characteristics 
of the invention.”). See also AK Steel Corp. v. 
Sollac, 344 F3.d 1234, 1239-1240, 68 USPQ2d 1280, 
1283-84 (Fed. Cir. 2003); In re Janakirama-Rao, 
317 
F.2d 951, 954, 137 USPQ 893, 895-96 (CCPA 
1963). If an applicant contends that additional steps or 
materials in the prior art are excluded by the recitation 
of “consisting essentially of,” applicant has the burden 
of showing that the introduction of additional 
steps or components would materially change the 
characteristics of applicant’s invention. In re De 
Lajarte, 337 F.2d 870, 143 USPQ 256 (CCPA 1964). 
See also MPEP § 2111.03. The claim as a whole, 
including all limitations found in the preamble (see 
Pac-Tec Inc. v. Amerace Corp., 903 F.2d 796, 801, 
14 
USPQ2d 1871, 1876 (Fed. Cir. 1990) (determining 
that preamble language that constitutes a structural 
limitation is actually part of the claimed invention)), 
the transitional phrase, and the body of the claim, 
must be sufficiently supported to satisfy the written 
description requirement. An applicant shows possession 
of the claimed invention by describing the 
claimed invention with all of its limitations. Lockwood, 
107 F.3d at 1572, 41 
USPQ2d at 1966.

The examiner should evaluate each claim to determine 
if sufficient structures, acts, or functions are 
recited to make clear the scope and meaning of the 
claim, including the weight to be given the preamble. 
See, e.g., Bell Communications Research, Inc. v. 
Vitalink Communications Corp., 55 F.3d 615, 620, 
34 
USPQ2d 1816, 1820 (Fed. Cir. 1995) (“[A] claim 
preamble has the import that the claim as a whole suggests 
for it.”); Corning Glass Works v. Sumitomo Elec. 
U.S.A., Inc., 868 F.2d 1251, 1257, 9 USPQ2d 1962, 
1966 (Fed. Cir. 1989) (The determination of whether 
preamble recitations are structural limitations can be 
resolved only on review of the entirety of the application 
“to gain an understanding of what the inventors 
actually invented and intended to encompass by the 
claim.”). The absence of definitions or details for 
well-established terms or procedures should not be 
the basis of a rejection under 35 U.S.C. 112, para. 1, 
for lack of adequate written description. Limitations 
may not, however, be imported into the claims from 
the specification.





2.Review the Entire Application to Understand 
How Applicant Provides Support for the 
Claimed Invention Including Each Element 
and/or Step

Prior to determining whether the disclosure satisfies 
the written description requirement for the 
claimed subject matter, the examiner should review 
the claims and the entire specification, including the 
specific embodiments, figures, and sequence listings, 
to understand how applicant provides support for the 
various features of the claimed invention. An element 
may be critical where those of skill in the art would 
require it to determine that applicant was in possession 
of the invention. Compare Rasmussen, 650 F.2d 
at 1215, 211 USPQ at 327 (“one skilled in the art who 
read Rasmussen’s specification would understand that 
it is unimportant how the layers are adhered, so long 
as they are adhered”) (emphasis in original), with 
Amgen, Inc. v. Chugai Pharmaceutical Co., Ltd., 927 
F.2d 1200, 1206, 18 USPQ2d 1016, 1021 (Fed. Cir. 
1991) (“it is well established in our law that conception 
of a chemical compound requires that the inventor 
be able to define it so as to distinguish it from 
other materials, and to describe how to obtain it”). 
The analysis of whether the specification complies 
with the written description requirement calls for the 
examiner to compare the scope of the claim with the 
scope of the description to determine whether applicant 
has demonstrated possession of the claimed 
invention. Such a review is conducted from the standpoint 
of one of skill in the art at the time the application 
was filed (see, e.g., Wang Labs. v. Toshiba Corp., 
993 F.2d 858, 865, 26 USPQ2d 1767, 1774 (Fed. Cir. 
1993)) and should include a determination of the field 
of the invention and the level of skill and knowledge 
in the art. Generally, there is an inverse correlation 
between the level of skill and knowledge in the art 
and the specificity of disclosure necessary to satisfy 
the written description requirement. Information 
which is well known in the art need not be described 
in detail in the specification. See, e.g., Hybritech, Inc. 
v. Monoclonal Antibodies, Inc., 802 F.2d 1367, 1379-
80, 231 USPQ 81, 90 (Fed. Cir. 1986).

3.Determine Whether There is Sufficient Written 
Description to Inform a Skilled Artisan 
That Applicant was in Possession of the 
Claimed Invention as a Whole at the Time 
the Application Was Filed

(a) Original claims 

Possession may be shown in many ways. For example, 
possession may be shown by describing an actual 
reduction to practice of the claimed invention. Possession 
may also be shown by a clear depiction of the 
invention in detailed drawings or in structural chemical 
formulas which permit a person skilled in the art 
to clearly recognize that applicant had possession of 
the claimed invention. An adequate written description 
of the invention may be shown by any description 
of sufficient, relevant, identifying characteristics so 
long as a person skilled in the art would recognize that 
the inventor had possession of the claimed invention. 
See, e.g., Purdue Pharma L.P. v. Faulding Inc., 230 
F.3d 1320, 1323, 56 USPQ2d 1481, 1483 (Fed. Cir. 
2000) (the written description “inquiry is a factual one 
and must be assessed on a case-by-case basis”); see 
also Pfaff v. Wells Electronics, Inc., 55 U.S. at 66, 119 
S.Ct. at 311, 48 USPQ2d at 1646 (“The word ‘invention’ 
must refer to a concept that is complete, rather 
than merely one that is ‘substantially complete.’ It is 
true that reduction to practice ordinarily provides the 
best evidence that an invention is complete. But just 
because reduction to practice is sufficient evidence of 
completion, it does not follow that proof of reduction 
to practice is necessary in every case. Indeed, both the 
facts of the Telephone Cases and the facts of this case 
demonstrate that one can prove that an invention is 
complete and ready for patenting before it has actually 
been reduced to practice.”).

A specification may describe an actual reduction to 
practice by showing that the inventor constructed an 
embodiment or performed a process that met all the 
limitations of the claim and determined that the invention 
would work for its intended purpose. Cooper v. 
Goldfarb, 154 F.3d 1321, 1327, 47 USPQ2d 1896, 
1901 (Fed. Cir. 1998). See also UMC Elecs. Co. v. 
United States, 816 F.2d 647, 652, 2 USPQ2d 1465, 
1468 (Fed. Cir. 1987) (“[T]here cannot be a reduction 
to practice of the invention    without a physical 
embodiment which includes all limitations of the 
claim.”); Estee Lauder Inc. v. L’Oreal, S.A., 129 F.3d 





588, 593, 44 USPQ2d 1610, 1614 (Fed. Cir. 1997) 
(“[A] reduction to practice does not occur until the 
inventor has determined that the invention will work 
for its intended purpose.”); Mahurkar v. C.R. Bard, 
Inc., 79 F.3d 1572, 1578, 38 USPQ2d 1288, 1291 
(Fed. Cir. 1996) (determining that the invention will 
work for its intended purpose may require testing 
depending on the character of the invention and the 
problem it solves). Description of an actual reduction 
to practice of a biological material may be shown by 
specifically describing a deposit made in accordance 
with the requirements of 37 CFR 1.801 et seq. See 
especially 37 CFR 1.804 and 1.809. See also paragraph 
I., supra.

An applicant may show possession of an invention 
by disclosure of drawings or structural chemical formulas 
that are sufficiently detailed to show that applicant 
was in possession of the claimed invention as a 
whole. See, e.g., Vas-Cath, 935 F.2d at 1565, 
19 
USPQ2d at 1118 (“drawings alone may provide a 
‘written description’ of an invention as required by 
Sec. 112”); In re Wolfensperger, 302 F.2d 950, 133 
USPQ 537 (CCPA 1962) (the drawings of applicant’s 
specification provided sufficient written descriptive 
support for the claim limitation at issue); Autogiro Co. 
of America v. United States, 384 F.2d 391, 398, 
155 
USPQ 697, 703 (Ct. Cl. 1967) (“In those 
instances where a visual representation can flesh out 
words, drawings may be used in the same manner and 
with the same limitations as the specification.”); Eli 
Lilly, 119 F.3d at 1568, 43 USPQ2d at 1406 (“In 
claims involving chemical materials, generic formulae 
usually indicate with specificity what the generic 
claims encompass. One skilled in the art can distinguish 
such a formula from others and can identify 
many of the species that the claims encompass. 
Accordingly, such a formula is normally an adequate 
description of the claimed genus.”). The description 
need only describe in detail that which is new or not 
conventional. See Hybritech v. Monoclonal Antibodies, 
802 F.2d at 1384, 231 USPQ at 94; Fonar Corp. v. 
General Electric Co., 107 F.3d at 1549, 41 USPQ2d at 
1805 (source code description not required). This is 
equally true whether the claimed invention is directed 
to a product or a process.

An applicant may also show that an invention is 
complete by disclosure of sufficiently detailed, relevant 
identifying characteristics which provide evidence 
that applicant was in possession of the claimed 
invention, i.e., complete or partial structure, other 
physical and/or chemical properties, functional characteristics 
when coupled with a known or disclosed 
correlation between function and structure, or some 
combination of such characteristics. Enzo Biochem, 
323 F.3d at 964, 63 USPQ2d at 1613. For example, 
the presence of a restriction enzyme map of a gene 
may be relevant to a statement that the gene has been 
isolated. One skilled in the art may be able to determine 
whether the gene disclosed is the same as or different 
from a gene isolated by another by comparing 
the restriction enzyme maps. In contrast, evidence that 
the gene could be digested with a nuclease would not 
normally represent a relevant characteristic since any 
gene would be digested with a nuclease. Similarly, 
isolation of an mRNA and its expression to produce 
the protein of interest is strong evidence of possession 
of an mRNA for the protein.

For some biomolecules, examples of identifying 
characteristics include a sequence, structure, binding 
affinity, binding specificity, molecular weight, and 
length. Although structural formulas provide a convenient 
method of demonstrating possession of specific 
molecules, other identifying characteristics or combinations 
of characteristics may demonstrate the requisite 
possession. As explained by the Federal Circuit, 
“(1) examples are not necessary to support the adequacy 
of a written description; (2) the written description 
standard may be met … even where actual 
reduction to practice of an invention is absent; and (3) 
there is no per se rule that an adequate written 
description of an invention that involves a biological 
macromolecule must contain a recitation of known 
structure.” Falkner v. Inglis, 448 F.3d 1357, 1366, 79 
USPQ2d 1001, 1007 (Fed. Cir. 2006). See also Capon 
v. Eshhar, 418 F.3d at 1358, 76 USPQ2d at 1084 
(“The Board erred in holding that the specifications 
do not meet the written description requirement 
because they do not reiterate the structure or formula 
or chemical name for the nucleotide sequences of the 
claimed chimeric genes” where the genes were 
novel 
combinations of known DNA segments.). For 
example, disclosure of an antigen fully characterized 
by its structure, formula, chemical name, physical 
properties, or deposit in a public depository provides 
an adequate written description of an antibody 
claimed by 
its binding affinity to that antigen. Noelle 





v. Lederman, 355 F.3d 1343, 1349, 69 USPQ2d 1508, 
1514 (Fed. Cir. 2004) (holding there is a lack of written 
descriptive support for an antibody defined by its 
binding affinity to an antigen that itself was not adequately 
described). Additionally, unique cleavage by 
particular enzymes, isoelectric points of fragments, 
detailed restriction enzyme maps, a comparison of 
enzymatic activities, or antibody cross-reactivity may 
be sufficient to show possession of the claimed invention 
to one of skill in the art. See Lockwood, 107 F.3d 
at 1572, 41 USPQ2d at 1966 (“written description” 
requirement may be satisfied by using “such descriptive 
means as words, structures, figures, diagrams, 
formulas, etc., that fully set forth the claimed invention”). 
A definition by function alone “does not suffice” 
to sufficiently describe a coding sequence 
“because it is only an indication of what the gene 
does, rather than what it is.” Eli Lilly, 119 F.3 at 1568, 
43 USPQ2d at 1406. See also Fiers, 984 F.2d at 1169-
71, 25 USPQ2d at 1605-06 (discussing Amgen Inc. v. 
Chugai Pharmaceutical Co., 927 F.2d 1200, 
18 
USPQ2d 1016 (Fed. Cir. 1991)). An adequate written 
description of a chemical invention also requires a 
precise definition, such as by structure, formula, 
chemical name, or physical properties, and not merely 
a wish or plan for obtaining the chemical invention 
claimed. See, e.g., Univ. of Rochester v. G.D. Searle & 
Co., 358 F.3d 916, 927, 69 USPQ2d 1886, 1894-95 
(Fed. Cir. 2004) (The patent at issue claimed a method 
of selectively inhibiting PGHS-2 activity by administering 
a non-steroidal compound that selectively 
inhibits activity of the PGHS-2 gene product, however 
the patent did not disclose any compounds that 
can be used in the claimed methods. While there was 
a description of assays for screening compounds to 
identify those that inhibit the expression or activity of 
the PGHS-2 gene product, there was no disclosure of 
which peptides, polynucleotides, and small organic 
molecules selectively inhibit PGHS-2. The court held 
that “[w]ithout such disclosure, the claimed methods 
cannot be said to have been described.”).

If a claim limitation invokes 35 U.S.C. 112, para. 6, 
it must be interpreted to cover the corresponding 
structure, materials, or acts in the specification and 
“equivalents thereof.” See 35 U.S.C. 112, para. 6. See 
also B. Braun Medical, Inc. v. Abbott Lab., 124 F.3d 
1419, 1424, 43 USPQ2d 1896, 1899 (Fed. Cir. 1997). 
In considering whether there is 35 U.S.C. 112, para. 1, 
support for a means- (or step) plus-function claim 
limitation, the examiner must consider not only the 
original disclosure contained in the summary and 
detailed description of the invention portions of the 
specification, but also the original claims, abstract, 
and drawings. A means- (or step-) plus-function claim 
limitation is adequately described under 35 U.S.C. 
112, para. 1, if: (1) The written description adequately 
links or associates adequately described particular 
structure, material, or acts to the function recited in a 
means- (or step-) plus-function claim limitation; or 
(2) it is clear based on the facts of the application that 
one skilled in the art would have known what structure, 
material, or acts perform the function recited in a 
means- (or step-) plus-function limitation. Note also: 
A rejection under 35 U.S.C. 112, para. 2, “cannot 
stand where there is adequate description in the specification 
to satisfy 35 U.S.C. 112, first paragraph, 
regarding means-plus-function recitations that are not, 
per se, challenged for being unclear.” In re Noll, 
545 
F.2d 141, 149, 191 USPQ 721, 727 (CCPA 1976). 
See Supplemental Examination Guidelines for Determining 
the Applicability of 35 U.S.C. 112, para. 6, 
65 
Fed. Reg. 38510, June 21, 2000. See also MPEP 
§
2181.

What is conventional or well known to one of ordinary 
skill in the art need not be disclosed in detail. See 
Hybritech Inc. v. Monoclonal Antibodies, Inc., 
802 
F.2d at 1384, 231 USPQ at 94. See also Capon 
v. Eshhar, 418 F.3d 1349, 1357, 76 USPQ2d 1078, 
1085 (Fed. Cir. 2005)(“The ‘written description’ 
requirement must be applied in the context of the particular 
invention and the state of the knowledge…. As 
each field evolves, the balance also evolves between 
what is known and what is added by each inventive 
contribution.”). If a skilled artisan would have 
understood the inventor to be in possession of the 
claimed invention at the time of filing, even if every 
nuance of the claims is not explicitly described in the 
specification, then the adequate description requirement 
is met. See, e.g., Vas-Cath, 935 F.2d at 1563, 19 
USPQ2d at 1116; Martin v. Johnson, 454 F.2d 746, 
751, 172 USPQ 391, 395 (CCPA 1972) (stating “the 
description need not be in ipsis verbis [i.e., “in the 
same words”] to be sufficient”).

A claim which is limited to a single disclosed 
embodiment or species is analyzed as a claim drawn 
to a single embodiment or species, whereas a claim 





which encompasses two or more embodiments or species 
within the scope of the claim is analyzed as a 
claim drawn to a genus. See also MPEP § 806.04(e).

i)For Each Claim Drawn to a Single Embodiment 
Or Species: 

(A)Determine whether the application describes 
an actual reduction to practice of the claimed invention.


(B)If the application does not describe an actual 
reduction to practice, determine whether the invention 
is complete as evidenced by a reduction to drawings 
or structural chemical formulas that are sufficiently 
detailed to show that applicant was in possession of 
the claimed invention as a whole.

(C)If the application does not describe an actual 
reduction to practice or reduction to drawings or 
structural chemical formula as discussed above, determine 
whether the invention has been set forth in terms 
of distinguishing identifying characteristics as evidenced 
by other descriptions of the invention that are 
sufficiently detailed to show that applicant was in possession 
of the claimed invention.

(1)Determine whether the application as filed 
describes the complete structure (or acts of a process) 
of the claimed invention as a whole. The complete 
structure of a species or embodiment typically satisfies 
the requirement that the description be set forth 
“in such full, clear, concise, and exact terms” to show 
possession of the claimed invention. 35 U.S.C. 112, 
para. 1. Cf. Fields v. Conover, 443 F.2d 1386, 1392, 
170 USPQ 276, 280 (CCPA 1971) (finding a lack of 
written description because the specification lacked 
the “full, clear, concise, and exact written description” 
which is necessary to support the claimed invention). 
If a complete structure is disclosed, the written 
description requirement is satisfied for that species or 
embodiment, and a rejection under 35 U.S.C. 112, 
para. 1, for lack of written description must not be 
made.

(2)If the application as filed does not disclose 
the complete structure (or acts of a process) of the 
claimed invention as a whole, determine whether the 
specification discloses other relevant identifying characteristics 
sufficient to describe the claimed invention 
in such full, clear, concise, and exact terms that a 
skilled artisan would recognize applicant was in possession 
of the claimed invention. For example, if the 
art has established a strong correlation between structure 
and function, one skilled in the art would be able 
to predict with a reasonable degree of confidence the 
structure of the claimed invention from a recitation of 
its function. Thus, the written description requirement 
may be satisfied through disclosure of function and 
minimal structure when there is a well-established 
correlation between structure and function. In contrast, 
without such a correlation, the capability to recognize 
or understand the structure from the mere 
recitation of function and minimal structure is highly 
unlikely. In this latter case, disclosure of function 
alone is little more than a wish for possession; it does 
not satisfy the written description requirement. See 
Eli Lilly, 119 F.3d at 1568, 43 USPQ2d at 1406 (written 
description requirement not satisfied by merely 
providing “a result that one might achieve if one made 
that invention”); In re Wilder, 736 F.2d 1516, 1521, 
222 USPQ 369, 372-73 (Fed. Cir. 1984) (affirming a 
rejection for lack of written description because the 
specification does “little more than outline goals 
appellants hope the claimed invention achieves and 
the problems the invention will hopefully ameliorate”). 
Compare Fonar, 107 F.3d at 1549, 41 USPQ2d 
at 1805 (disclosure of software function adequate in 
that art).

 Whether the specification shows that applicant was 
in possession of the claimed invention is not a single, 
simple determination, but rather is a factual determination 
reached by considering a number of factors. 
Factors to be considered in determining whether there 
is sufficient evidence of possession include the level 
of skill and knowledge in the art, partial structure, 
physical and/or chemical properties, functional characteristics 
alone or coupled with a known or disclosed 
correlation between structure and function, and the 
method of making the claimed invention. Disclosure 
of any combination of such identifying characteristics 
that distinguish the claimed invention from other 
materials and would lead one of skill in the art to the 
conclusion that the applicant was in possession of the 
claimed species is sufficient. See Eli Lilly, 119 F.3d at 
1568, 43 USPQ2d at 1406. The description needed 
to satisfy the requirements of 35 U.S.C. 112 “varies 
with the nature and scope of the invention at issue, 
and with the scientific and technologic knowledge 
already in existence.” Capon v. Eshhar, 418 F.3d at 





1357, 76 USPQ2d at 1084. Patents and printed publications 
in the art should be relied upon to determine 
whether an art is mature and what the level of knowledge 
and skill is in the art. In most technologies which 
are mature, and wherein the knowledge and level of 
skill in the art is high, a written description question 
should not be raised for  claims present in the application 
when originally filed, even if the specification 
discloses only a method of making the invention and 
the function of the invention. See, e.g., In re Hayes 
Microcomputer Products, Inc. Patent Litigation, 982 
F.2d 1527, 1534-35, 25 USPQ2d 1241, 1246 (Fed. 
Cir. 1992) (“One skilled in the art would know how to 
program a microprocessor to perform the necessary 
steps described in the specification. Thus, an inventor 
is not required to describe every detail of his invention. 
An applicant’s disclosure obligation varies 
according to the art to which the invention pertains. 
Disclosing a microprocessor capable of performing 
certain functions is sufficient to satisfy the requirement 
of section 112, first paragraph, when one skilled 
in the relevant art would understand what is intended 
and know how to carry it out.”). 

In contrast, for inventions in emerging and unpredictable 
technologies, or for inventions characterized 
by factors not reasonably predictable which are 
known to one of ordinary skill in the art, more evidence 
is required to show possession. For example, 
disclosure of only a method of making the invention 
and the function may not be sufficient to support a 
product claim other than a product-by-process claim. 
See, e.g., Fiers v. Revel, 984 F.2d at 1169, 25 USPQ2d 
at 1605; Amgen, 927 
F.2d at 1206, 18 USPQ2d at 
1021. Where the process has actually been used to 
produce the product, the written description requirement 
for a product-by-process claim is clearly satisfied; 
however, the requirement may not be satisfied 
where it is not clear that the acts set forth in the specification 
can be performed, or that the product is produced 
by that process. Furthermore, disclosure of a 
partial structure without additional characterization of 
the product may not be sufficient to evidence possession 
of the claimed invention. See, e.g., Amgen, 927 
F.2d at 1206, 18 
USPQ2d at 1021 (“A gene is a chemical 
compound, albeit a complex one, and it is well 
established in our law that conception of a chemical 
compound requires that the inventor be able to define 
it so as to distinguish it from other materials, and to 
describe how to obtain it. Conception does not occur 
unless one has a mental picture of the structure of the 
chemical, or is able to define it by its method of preparation, 
its physical or chemical properties, or whatever 
characteristics sufficiently distinguish it. It is not 
sufficient to define it solely by its principal biological 
property, e.g., encoding human erythropoietin, 
because an alleged conception having no more specificity 
than that is simply a wish to know the identity 
of any material with that biological property. We hold 
that when an inventor is unable to envision the 
detailed constitution of a gene so as to distinguish it 
from other materials, as well as a method for obtaining 
it, conception has not been achieved until reduction 
to practice has occurred, i.e., until after the gene 
has been isolated.”) (citations omitted). In such 
instances the alleged conception fails not merely 
because the field is unpredictable or because of the 
general uncertainty surrounding experimental sciences, 
but because the conception is incomplete due 
to factual uncertainty that undermines the specificity 
of the inventor’s idea of the invention. Burroughs 
Wellcome Co. v. Barr Laboratories Inc., 40 
F.3d 1223, 
1229, 32 USPQ2d 1915, 1920 (Fed. Cir. 1994). 
Reduction to practice in effect provides the only evidence 
to corroborate conception (and therefore possession) 
of the invention. Id.

Any claim to a species that does not meet the test 
described under at least one of (a), (b), or (c) must be 
rejected as lacking adequate written description under 
35 U.S.C. 112, para. 1.

ii)For each claim drawn to a genus:

 The written description requirement for a claimed 
genus may be satisfied through sufficient description 
of a representative number of species by actual reduction 
to practice (see i)(A), above), reduction to drawings 
(see i)(B), above), or by disclosure of relevant, 
identifying characteristics, i.e., structure or other 
physical and/or chemical properties, by functional 
characteristics coupled with a known or disclosed correlation 
between function and structure, or by a combination 
of such identifying characteristics, sufficient 
to show the applicant was in possession of the 
claimed genus (see i)(C), above). See Eli Lilly, 
119 
F.3d at 1568, 43 USPQ2d at 1406.





 A “representative number of species” means that 
the species which are adequately described are representative 
of the entire genus. Thus, when there is substantial 
variation within the genus, one must describe 
a sufficient variety of species to reflect the variation 
within the genus. The disclosure of only one species 
encompassed within a genus adequately describes a 
claim directed to that genus only if the disclosure 
“indicates that the patentee has invented species sufficient 
to constitute the gen[us].” See Enzo Biochem, 
323 F.3d at 966, 63 USPQ2d at 1615; Noelle v. Lederman, 
355 F.3d 1343, 1350, 69 USPQ2d 1508, 1514 
(Fed. Cir. 2004) (Fed. Cir. 2004)(“[A] patentee of a 
biotechnological invention cannot necessarily claim a 
genus after only describing a limited number of species 
because there may be unpredictability in the 
results obtained from species other than those specifically 
enumerated.”). “A patentee will not be deemed 
to have invented species sufficient to constitute the 
genus by virtue of having disclosed a single species 
when … the evidence indicates ordinary artisans 
could not predict the operability in the invention of 
any species other than the one disclosed.” In re Curtis, 
354 F.3d 1347, 1358, 69 USPQ2d 1274, 1282 (Fed. 
Cir. 2004)(Claims directed to PTFE dental floss with a 
friction-enhancing coating were not supported by a 
disclosure of a microcrystalline wax coating where 
there was no evidence in the disclosure or anywhere 
else in the record showing applicant conveyed that 
any other coating was suitable for a PTFE dental 
floss.) On the other hand, there may be situations 
where one species adequately supports a genus. See, 
e.g., Rasmussen, 650 F.2d at 1214, 211 
USPQ at 326-
27 (disclosure of a single method of adheringly applying 
one layer to another was sufficient to support a 
generic claim to “adheringly applying” because one 
skilled in the art reading the specification would 
understand that it is unimportant how the layers are 
adhered, so long as they are adhered); In re Herschler, 
591 F.2d 693, 697, 200 
USPQ 711, 714 (CCPA 1979) 
(disclosure of corticosteroid in DMSO sufficient to 
support claims drawn to a method of using a mixture 
of a “physiologically active steroid” and DMSO 
because “use of known chemical compounds in a 
manner auxiliary to the invention must have a corresponding 
written description only so specific as to 
lead one having ordinary skill in the art to that class of 
compounds. Occasionally, a functional recitation of 
those known compounds in the specification may be 
sufficient as that description.”); In re Smythe, 480 
F.2d 1376, 1383, 178 USPQ 279, 285 (CCPA 1973) 
(the phrase “air or other gas which is inert to the liquid” 
was sufficient to support a claim to “inert fluid 
media” because the description of the properties and 
functions of the air or other gas segmentizing medium 
would suggest to a person skilled in the art that appellant’s 
invention includes the use of “inert fluid” 
broadly.). 

The Federal Circuit has explained that a specification 
cannot always support expansive claim language 
and satisfy the requirements of 35 U.S.C. 112“merely by clearly describing one embodiment of the 
thing claimed.” LizardTech v. Earth Resource Mapping, 
Inc., 424 F.3d 1336, 1346, 76 USPQ2d 1731, 
1733 (Fed. Cir. 2005). The issue is whether a person 
skilled in the art would understand applicant to have 
invented, and been in possession of, the invention as 
broadly claimed. In LizardTech, claims to a generic 
method of making a seamless discrete wavelet transformation 
(DWT) were held invalid under 35 U.S.C. 
112, first paragraph because the specification taught 
only one particular method for making a seamless 
DWT and there was no evidence that the specification 
contemplated a more generic method. See also
Tronzo v. Biomet, 156 F.3d at 1159, 47 USPQ2d at 
1833 (Fed. Cir. 1998), wherein the disclosure of 
a 
species in the parent application did not suffice to 
provide written description support for the genus in 
the child application. 

What constitutes a “representative number” is an 
inverse function of the skill and knowledge in the art. 
Satisfactory disclosure of a “representative number” 
depends on whether one of skill in the art would recognize 
that the applicant was in possession of the necessary 
common attributes or features of the elements 
possessed by the members of the genus in view of the 
species disclosed. For inventions in an unpredictable 
art, adequate written description of a genus which 
embraces widely variant species cannot be achieved 
by disclosing only one species within the genus. See, 
e.g., Eli Lilly. Description of a representative number 
of species does not require the description to be of 
such specificity that it would provide individual support 
for each species that the genus embraces. For 
example, in the molecular biology arts, if an 
applicant 
disclosed an amino acid sequence, it would 





be unnecessary to provide an explicit disclosure of 
nucleic acid sequences that encoded the amino acid 
sequence. Since the genetic code is widely known, a 
disclosure of an amino acid sequence would provide 
sufficient information such that one would accept that 
an applicant was in possession of the full genus of 
nucleic acids encoding a given amino acid sequence, 
but not necessarily any particular species. Cf. In re 
Bell, 991 F.2d 781, 785, 26 USPQ2d 1529, 1532 (Fed. 
Cir. 1993) and In re Baird, 16 F.3d 380, 382, 29 
USPQ2d 1550, 1552 (Fed. Cir. 1994). If a representative 
number of adequately described species are not 
disclosed for a genus, the claim to that genus must be 
rejected as lacking adequate written description under 
35 U.S.C. 112, para. 1.

(b)New Claims, Amended Claims, or Claims 
Asserting Entitlement to the Benefit of an 
Earlier Priority Date or Filing Date under 
35 
U.S.C. 119, 120, or 365(c)

The examiner has the initial burden of presenting 
evidence or reasoning to explain why persons skilled 
in the art would not recognize in the original disclosure 
a description of the invention defined by the 
claims. See Wertheim, 541 F.2d at 263, 191 USPQ at 
97 (“[T]he PTO has the initial burden of presenting 
evidence or reasons why persons skilled in the art 
would not recognize in the disclosure a description of 
the invention defined by the claims.”). However, 
when filing an amendment an applicant should show 
support in the original disclosure for new or amended 
claims. See MPEP § 714.02 and § 2163.06 (“Applicant 
should    specifically point out the support for 
any amendments made to the disclosure.”). 

To comply with the written description requirement 
of 35 U.S.C. 112, para. 1, or to be entitled to an earlier 
priority date or filing date under 35 U.S.C. 119, 120, 
or 365(c), each claim limitation must be expressly, 
implicitly, or inherently supported in the originally 
filed disclosure. When an explicit limitation in a claim 
“is not present in the written description whose benefit 
is sought it must be shown that a person of ordinary 
skill would have understood, at the time the patent 
application was filed, that the description requires that 
limitation.” Hyatt v. Boone, 146 F.3d 1348, 1353, 
47 
USPQ2d 1128, 1131 (Fed. Cir. 1998). See also In 
re Wright, 866 F.2d 422, 425, 9 USPQ2d 1649, 1651 
(Fed. Cir. 1989) (Original specification for method of 
forming images using photosensitive microcapsules 
which describes removal of microcapsules from surface 
and warns that capsules not be disturbed prior to 
formation of image, unequivocally teaches absence of 
permanently fixed microcapsules and supports 
amended language of claims requiring that microcapsules 
be “not permanently fixed” to underlying surface, 
and therefore meets description requirement of 
35 U.S.C. 112.); In re Robins, 429 F.2d 452, 456-57, 
166 USPQ 552, 555 (CCPA 1970) (“[W]here no 
explicit description of a generic invention is to be 
found in the specification[,] ... mention of representative 
compounds may provide an implicit description 
upon which to base generic claim language.”); In re 
Smith, 458 F.2d 1389, 1395, 173 USPQ 679, 683 
(CCPA 1972) (a subgenus is not necessarily implicitly 
described by a genus encompassing it and a species 
upon which it reads); In re Robertson, 169 F.3d 743, 
745, 49 USPQ2d 1949, 1950-51 (Fed. Cir. 1999) (“To 
establish inherency, the extrinsic evidence ‘must 
make clear that the missing descriptive matter is necessarily 
present in the thing described in the reference, 
and that it would be so recognized by persons of ordinary 
skill. Inherency, however, may not be established 
by probabilities or possibilities. The mere fact that a 
certain thing may result from a given set of circumstances 
is not sufficient.’”) (citations omitted). Furthermore, 
each claim must include all elements which 
applicant has described as essential. See, e.g., 
Johnson Worldwide Associates Inc. v. Zebco Corp., 
175 F.3d at 993, 50 USPQ2d at 1613; Gentry Gallery, 
Inc. v. Berkline Corp., 134 F.3d at 1479, 45 USPQ2d 
at 1503; Tronzo v. Biomet, 156 F.3d at 1159, 
47 
USPQ2d at 1833.

If the originally filed disclosure does not provide 
support for each claim limitation, or if an element 
which applicant describes as essential or critical is not 
claimed, a new or amended claim must be rejected 
under 35 U.S.C. 112, para. 1, as lacking adequate 
written description, or in the case of a claim for priority 
under 35 U.S.C. 119, 120, or 365(c), the claim for 
priority must be denied.





III.COMPLETE PATENTABILITY DETER-
MINATION UNDER ALL STATUTORY REQUIREMENTS 
AND CLEARLY COMMUNICATE 
FINDINGS, CONCLUSIONS, AND 
THEIR BASES

The above only describes how to determine 
whether the written description requirement of 
35 
U.S.C. 112, para. 1, is satisfied. Regardless of the 
outcome of that determination, Office personnel must 
complete the patentability determination under all the 
relevant statutory provisions of title 35 of the U.S. 
Code.

Once Office personnel have concluded analysis of 
the claimed invention under all the statutory provisions, 
including 35 U.S.C. 101, 112, 102, and 103, 
they should review all the proposed rejections and 
their bases to confirm their correctness. Only then 
should any rejection be imposed in an Office action. 
The Office action should clearly communicate the 
findings, conclusions, and reasons which support 
them. When possible, the Office action should offer 
helpful suggestions on how to overcome rejections.

A.For Each Claim Lacking Written Description 
Support, Reject the Claim Under 35 U.S.C. 
112, para. 1, for Lack of Adequate Written Description


A description as filed is presumed to be adequate, 
unless or until sufficient evidence or reasoning to the 
contrary has been presented by the examiner to rebut 
the presumption. See, e.g., In re Marzocchi, 439 F.2d 
220, 224, 169 USPQ 367, 370 (CCPA 1971). The 
examiner, therefore, must have a reasonable basis to 
challenge the adequacy of the written description. The 
examiner has the initial burden of presenting by a preponderance 
of evidence why a person skilled in the art 
would not recognize in an applicant’s disclosure a 
description of the invention defined by the claims. 
Wertheim, 541 F.2d at 263, 191 USPQ at 97. In rejecting 
a claim, the examiner must set forth express findings 
of fact regarding the above analysis which 
support the lack of written description conclusion. 
These findings should:

(A)Identify the claim limitation at issue; and

(B)Establish a prima facie case by providing reasons 
why a person skilled in the art at the time the 
application was filed would not have recognized that 
the inventor was in possession of the invention as 
claimed in view of the disclosure of the application as 
filed. A general allegation of “unpredictability in the 
art” is not a sufficient reason to support a rejection for 
lack of adequate written description.

 When appropriate, suggest amendments to the 
claims which can be supported by the application’s 
written description, being mindful of the prohibition 
against the addition of new matter in the claims or 
description. See Rasmussen, 650 F.2d at 1214, 
211 
USPQ at 326.

B.Upon Reply by Applicant, Again Determine 
the Patentability of the Claimed Invention, 
Including Whether the Written Description 
Requirement Is Satisfied by Reperforming the 
Analysis Described Above in View of the 
Whole Record

 Upon reply by applicant, before repeating any 
rejection under 35 U.S.C. 112, para. 1, for lack of 
written description, review the basis for the rejection 
in view of the record as a whole, including amendments, 
arguments, and any evidence submitted by 
applicant. If the whole record now demonstrates that 
the written description requirement is satisfied, do not 
repeat the rejection in the next Office action. If the 
record still does not demonstrate that the written 
description is adequate to support the claim(s), repeat 
the rejection under 35 U.S.C. 112, para. 1, fully 
respond to applicant’s rebuttal arguments, and properly 
treat any further showings submitted by applicant 
in the reply. When a rejection is maintained, any affidavits 
relevant to the 112, para. 1, written description 
requirement, must be thoroughly analyzed and discussed 
in the next Office action. See In re Alton, 
76 
F.3d 1168, 1176, 37 USPQ2d 1578, 1584 (Fed. Cir. 
1996).

2163.01Support for the Claimed SubjectMatter in Disclosure

A written description requirement issue generally 
involves the question of whether the subject matter of 
a claim is supported by [conforms to] the disclosure 
of an application as filed. If the examiner concludes 
that the claimed subject matter is not supported 
[described] in an application as filed, this would result 
in a rejection of the claim on the ground of a lack of 





written description under 35 U.S.C. 112, first paragraph 
or denial of the benefit of the filing date of a 
previously filed application. The claim should not be 
rejected or objected to on the ground of new matter. 
As framed by the court in In re Rasmussen, 650 F.2d 
1212, 211 USPQ 323 (CCPA 1981), the concept of 
new matter is properly employed as a basis for objection 
to amendments to the abstract, specification or 
drawings attempting to add new disclosure to that 
originally presented. While the test or analysis of 
description requirement and new matter issues is the 
same, the examining procedure and statutory basis for 
addressing these issues differ. See MPEP § 2163.06.

2163.02Standard for Determining Compliance 
With the Written Description 
Requirement

The courts have described the essential question to 
be addressed in a description requirement issue in a 
variety of ways. An objective standard for determining 
compliance with the written description requirement 
is, “does the description clearly allow persons of 
ordinary skill in the art to recognize that he or she 
invented what is claimed.” In re Gosteli, 872 F.2d 
1008, 1012, 10 USPQ2d 1614, 1618 (Fed. Cir. 1989). 
Under Vas-Cath, Inc. v. Mahurkar, 935 F.2d 1555, 
1563-64, 19 USPQ2d 1111, 1117 (Fed. Cir. 1991), to 
satisfy the written description requirement, an applicant 
must convey with reasonable clarity to those 
skilled in the art that, as of the filing date sought, he or 
she was in possession of the invention, and that the 
invention, in that context, is whatever is now claimed. 
The test for sufficiency of support in a parent application 
is whether the disclosure of the application relied 
upon “reasonably conveys to the artisan that the 
inventor had possession at that time of the later 
claimed subject matter.” Ralston Purina Co. v. Far-
Mar-Co., Inc., 772 F.2d 1570, 1575, 227 USPQ 177, 
179 (Fed. Cir. 1985) (quoting In re Kaslow, 707 F.2d 
1366, 1375, 217 USPQ 1089, 1096 (Fed. Cir. 1983)).

Whenever the issue arises, the fundamental factual 
inquiry is whether the specification conveys with reasonable 
clarity to those skilled in the art that, as of the 
filing date sought, applicant was in possession of the 
invention as now claimed. See, e.g., Vas-Cath, Inc. v. 
Mahurkar, 935 F.2d 1555, 1563-64, 19 USPQ2d 
1111, 1117 (Fed. Cir. 1991). An applicant shows possession 
of the claimed invention by describing the 
claimed invention with all of its limitations using such 
descriptive means as words, structures, figures, diagrams, 
and formulas that fully set forth the claimed 
invention. Lockwood v. American Airlines, Inc., 
107 
F.3d 1565, 1572, 41 USPQ2d 1961, 1966 (Fed. 
Cir. 1997). Possession may be shown in a variety of 
ways including description of an actual reduction to 
practice, or by showing that the invention was “ready 
for patenting” such as by the disclosure of drawings 
or structural chemical formulas that show that the 
invention was complete, or by describing distinguishing 
identifying characteristics sufficient to show that 
the applicant was in possession of the claimed invention. 
See, e.g., Pfaff v. Wells Elecs., Inc., 525 U.S. 55, 
68, 119 S.Ct. 304, 312, 48 USPQ2d 1641, 1647 
(1998); Regents of the University of California v. Eli 
Lilly, 119 F.3d 1559, 1568, 43 USPQ2d 1398, 1406 
(Fed. Cir. 1997); Amgen, Inc. v. Chugai Pharmaceutical, 
927 F.2d 1200, 1206, 18 USPQ2d 1016, 1021 
(Fed. Cir. 1991) (one must define a compound by 
“whatever characteristics sufficiently distinguish it”).

The subject matter of the claim need not be 
described literally (i.e., using the same terms or in 
haec verba) in order for the disclosure to satisfy the 
description requirement. If a claim is amended to 
include subject matter, limitations, or terminology not 
present in the application as filed, involving a departure 
from, addition to, or deletion from the disclosure 
of the application as filed, the examiner should conclude 
that the claimed subject matter is not described 
in that application. This conclusion will result in the 
rejection of the claims affected under 35 U.S.C.112, 
first paragraph - description requirement, or denial of 
the benefit of the filing date of a previously filed 
application, as appropriate.

See MPEP § 2163 for examination guidelines pertaining 
to the written description requirement.

2163.03Typical Circumstances Where 
Adequate Written Description 
Issue Arises

A description requirement issue can arise in a number 
of different circumstances where it must be determined 
whether the subject matter of a claim is 
supported in an application as filed. See MPEP § 2163for examination guidelines pertaining to the written 
description requirement. While a question as to 
whether a specification provides an adequate written 





description may arise in the context of an original 
claim which is not described sufficiently (see, e.g.,
Regents of the University of California v. Eli Lilly, 
119 F.3d 1559, 43 USPQ2d 1398 (Fed. Cir. 1997)), 
there is a strong presumption that an adequate written 
description of the claimed invention is present in the 
specification as filed. In re Wertheim, 541 F.2d 257, 
262, 191 USPQ 90, 96 (CCPA 1976). Consequently, 
rejection of an original claim for lack of written 
description should be rare. Most typically, the issue 
will arise in the following circumstances: 

I.AMENDMENT AFFECTING A CLAIM

An amendment to the claims or the addition of a 
new claim must be supported by the description of the 
invention in the application as filed. In re Wright, 
866 
F.2d 422, 9 USPQ2d 1649 (Fed. Cir. 1989). An 
amendment to the specification (e.g., a change in the 
definition of a term used both in the specification and 
claim) may indirectly affect a claim even though no 
actual amendment is made to the claim. 

II.RELIANCE ON FILING DATE OF PARENT 
APPLICATION UNDER 35 U.S.C. 120

Under 35 U.S.C. 120, the claims in a U.S. application 
are entitled to the benefit of the filing date of an 
earlier filed U.S. application if the subject matter of 
the claim is disclosed in the manner provided by 
35 
U.S.C. 112, first paragraph in the earlier filed 
application. See, e.g., Tronzo v. Biomet, Inc., 156 F.3d 
1154, 47 USPQ2d 1829 (Fed. Cir. 1998); In reScheiber, 587 
F.2d 59, 199 USPQ 782 (CCPA 1978).

III.RELIANCE ON PRIORITY UNDER 35 
U.S.C. 119

Under 35 U.S.C. 119 (a) or (e), the claims in a U.S. 
application are entitled to the benefit of a foreign priority 
date or the filing date of a provisional application 
if the corresponding foreign application or 
provisional application supports the claims in the 
manner required by 35 U.S.C. 112, first paragraph. In 
re Ziegler, 992 F.2d 1197, 1200, 26 USPQ2d 1600, 
1603 (Fed. Cir. 1993); Kawai v. Metlesics, 480 F.2d 
880, 178 USPQ 158 (CCPA 1973); In re Gosteli, 872 
F.2d 1008, 10 USPQ2d 1614 (Fed. Cir. 1989).

IV.SUPPORT FOR A CLAIM CORRESPONDING 
TO A COUNT IN AN INTERFERENCE


In an interference proceeding, the claim corresponding 
to a count must be supported by the specification 
in the manner provided by 35 U.S.C. 112, first 
paragraph. Fields v. Conover, 443 F.2d 1386, 170 
USPQ 276 (CCPA 1971) (A broad generic disclosure 
to a class of compounds was not a sufficient written 
description of a specific compound within the class.). 
Furthermore, when a party to an interference seeks the 
benefit of an earlier-filed U.S. patent application, the 
earlier application must meet the requirements of 
35 
U.S.C. 112, first paragraph for the subject matter 
of the count. Hyatt v. Boone, 146 F.3d 1348, 1352, 
47 
USPQ2d 1128, 1130 (Fed. Cir. 1998).

2163.04Burden on the Examiner with 
Regard to the Written Description 
Requirement

The inquiry into whether the description requirement 
is met must be determined on a case-by-case 
basis and is a question of fact. In re Wertheim, 
541 
F.2d 257, 262, 191 USPQ 90, 96 (CCPA 1976). A 
description as filed is presumed to be adequate, unless 
or until sufficient evidence or reasoning to the contrary 
has been presented by the examiner to rebut the 
presumption. See, e.g., In re Marzocchi, 439 F.2d 220, 
224, 169 USPQ 367, 370 (CCPA 1971). The examiner, 
therefore, must have a reasonable basis to challenge 
the adequacy of the written description. The 
examiner has the initial burden of presenting by a preponderance 
of evidence why a person skilled in the art 
would not recognize in an applicant’s disclosure a 
description of the invention defined by the claims. 
Wertheim, 541 F.2d at 263, 191 USPQ at 97. 

I.STATEMENT OF REJECTION REQUIRE-
MENTS

In rejecting a claim, the examiner must set forth 
express findings of fact which support the lack of 
written description conclusion (see MPEP § 2163 for 
examination guidelines pertaining to the written 
description requirement). These findings should:

(A)Identify the claim limitation at issue; and





(B)Establish a prima facie case by providing reasons 
why a person skilled in the art at the time the 
application was filed would not have recognized that 
the inventor was in possession of the invention as 
claimed in view of the disclosure of the application as 
filed. A general allegation of “unpredictability in the 
art” is not a sufficient reason to support a rejection for 
lack of adequate written description. A simple statement 
such as “Applicant has not pointed out where 
the new (or amended) claim is supported, nor does 
there appear to be a written description of the claim 
limitation ‘____’ in the application as filed.” may be 
sufficient where the claim is a new or amended claim, 
the support for the limitation is not apparent, and 
applicant has not pointed out where the limitation is 
supported.

When appropriate, suggest amendments to the 
claims which can be supported by the application’s 
written description, being mindful of the prohibition 
against the addition of new matter in the claims or 
description. See Rasmussen, 650 F.2d at 1214, 
211 
USPQ at 326.

II.RESPONSE TO APPLICANT’S REPLY

Upon reply by applicant, before repeating any 
rejection under 35 U.S.C. 112, para. 1, for lack of 
written description, review the basis for the rejection 
in view of the record as a whole, including amendments, 
arguments, and any evidence submitted by 
applicant. If the whole record now demonstrates that 
the written description requirement is satisfied, do not 
repeat the rejection in the next Office action. If the 
record still does not demonstrate that the written 
description is adequate to support the claim(s), repeat 
the rejection under 35 U.S.C. 112, para. 1, fully 
respond to applicant’s rebuttal arguments, and properly 
treat any further showings submitted by applicant 
in the reply. When a rejection is maintained, any affidavits 
relevant to the 35 U.S.C. 112, para. 1, written 
description requirement, must be thoroughly analyzed 
and discussed in the next Office action. See In re 
Alton, 76 F.3d 1168, 1176, 37 USPQ2d 1578, 1584 
(Fed. Cir. 1996).

2163.05Changes to the Scope of Claims[R-2]

The failure to meet the written description requirement 
of 35 U.S.C. 112, first paragraph, commonly 
arises when the claims are changed after filing to 
either broaden or narrow the breadth of the claim limitations, 
or to alter a numerical range limitation or to 
use claim language which is not synonymous with the 
terminology used in the original disclosure. To comply 
with the written description requirement of 
35 
U.S.C. 112, para. 1, or to be entitled to an earlier 
priority date or filing date under 35 U.S.C. 119, 120, 
or 365(c), each claim limitation must be expressly, 
implicitly, or inherently supported in the originally 
filed disclosure. See MPEP § 2163 for examination 
guidelines pertaining to the written description 
requirement.

I.BROADENING CLAIM

Omission of a Limitation

Under certain circumstances, omission of a limitation 
can raise an issue regarding whether the inventor 
had possession of a broader, more generic invention. 
See, e.g., Gentry Gallery, Inc. v. Berkline Corp., 
134 
F.3d 1473, 45 USPQ2d 1498 (Fed. Cir. 1998) 
(claims to a sectional sofa comprising, inter alia, a 
console and a control means were held invalid for 
failing to satisfy the written description requirement 
where the claims were broadened by removing the 
location of the control means.); Johnson Worldwide 
Associates v. Zebco Corp., 175 F.3d 985, 993, 
50 
USPQ2d 1607, 1613 (Fed. Cir. 1999) (In Gentry 
Gallery, the “court’s determination that the patent disclosure 
did not support a broad meaning for the disputed 
claim terms was premised on clear statements 
in the written description that described the location 
of a claim element--the ‘control means’--as ‘the only 
possible location’ and that variations were 
‘outside 
the stated purpose of the invention.’ 
Gentry 
Gallery, 134 F.3d at 1479, 45 USPQ2d at 
1503. Gentry Gallery, then, considers the situation 
where the patent’s disclosure makes crystal clear that 
a particular (i.e., narrow) understanding of a claim 
term is an ‘essential element of [the inventor’s] invention.’”); 
Tronzo v. Biomet, 156 F.3d at 1158-59, 
47 
USPQ2d at 1833 (Fed. Cir. 1998) (claims to 





generic cup shape were not entitled to filing date of 
parent application which disclosed “conical cup” in 
view of the disclosure of the parent application stating 
the advantages and importance of the conical shape.); 
In re Wilder, 736 F.2d 1516, 222 USPQ 369 (Fed. Cir. 
1984) (reissue claim omitting “in synchronism” limitation 
with respect to scanning means and indexing 
means was not supported by the original patent’s disclosure 
in such a way as to indicate possession, as of 
the original filing date, of that generic invention.). 

A claim that omits an element which applicant 
describes as an essential or critical feature of the 
invention originally disclosed does not comply with 
the written description requirement. See Gentry Gallery, 
134 F.3d at 1480, 45 USPQ2d at 1503; In re Sus, 
306 F.2d 494, 504, 134 USPQ 301, 309 (CCPA 1962) 
(“[O]ne skilled in this art would not be taught by the 
written description of the invention in the specification 
that any ‘aryl or substituted aryl radical’ would 
be suitable for the purposes of the invention but rather 
that only certain aryl radicals and certain specifically 
substituted aryl radicals [i.e., aryl azides] would be 
suitable for such purposes.”) (emphasis in original). 
Compare In re Peters, 723 F.2d 891, 221 USPQ 952 
(Fed. Cir. 1983) (In a reissue application, a claim to a 
display device was broadened by removing the limitations 
directed to the specific tapered shape of the tips 
without violating the written description requirement. 
The shape limitation was considered to be unnecessary 
since the specification, as filed, did not describe 
the tapered shape as essential or critical to the operation 
or patentability of the claim.). A claim which 
omits matter disclosed to be essential to the invention 
as described in the specification or in other statements 
of record may also be subject to rejection under 
35 
U.S.C. 112, para. 1, as not enabling, or under 
35 
U.S.C. 112, para. 2. See In re Mayhew, 527 F.2d 
1229, 188 USPQ 356 (CCPA 1976); In re Venezia, 
530 F.2d 956, 189 USPQ 149 (CCPA 1976); and In re 
Collier, 397 F.2d 1003, 158 USPQ 266 (CCPA 1968). 
See also MPEP § 2172.01.

Addition of Generic Claim

The written description requirement for a claimed 
genus may be satisfied through sufficient description 
of a representative number of species. A “representative 
number of species” means that the species which 
are adequately described are representative of the 
entire genus. Thus, when there is substantial variation 
within the genus, one must describe a sufficient variety 
of species to reflect the variation within the genus. 
The disclosure of only one species encompassed 
within a genus adequately describes a claim directed 
to that genus only if the disclosure “indicates that the 
patentee has invented species sufficient to constitute 
the gen[us].” See Enzo Biochem, 323 F.3d at 966, 63 
USPQ2d at 1615. “A patentee will not be deemed to 
have invented species sufficient to constitute the 
genus by virtue of having disclosed a single species 
when … the evidence indicates ordinary artisans 
could not predict the operability in the invention of 
any species other than the one disclosed.” In re Curtis, 
354 F.3d 1347, 1358, 69 USPQ2d 1274, 1282 (Fed. 
Cir. 2004) (Claims directed to PTFE dental floss 
with 
a friction-enhancing coating were not supported by a 
disclosure of a microcrystalline wax coating where 
there was no evidence in the disclosure or anywhere 
else in the record showing applicant conveyed that 
any other coating was suitable for a PTFE dental 
floss.) On the other hand, there may be situations 
where one species adequately supports a genus. See, 
e.g., In re Rasmussen, 650 F.2d 1212, 1214, 211 
USPQ 323, 326-27 (CCPA 1981) (disclosure of a single 
method of adheringly applying one layer to 
another was sufficient to support a generic claim to 
“adheringly applying” because one skilled in the art 
reading the specification would understand that it is 
unimportant how the layers are adhered, so long as 
they are adhered); In re Herschler, 591 F.2d 693, 697, 
200 
USPQ 711, 714 (CCPA 1979) (disclosure of corticosteriod 
in DMSO sufficient to support claims 
drawn to a method of using a mixture of a “physiologically 
active steroid” and DMSO because “use of 
known chemical compounds in a manner auxiliary to 
the invention must have a corresponding written 
description only so specific as to lead one having 
ordinary skill in the art to that class of compounds. 
Occasionally, a functional recitation of those known 
compounds in the specification may be sufficient as 
that description.”); In re Smythe, 480 F.2d 1376, 1383, 
178 
USPQ 279, 285 (CCPA 1973) (the phrase “air or 
other gas which is inert to the liquid” was sufficient to 
support a claim to “inert fluid media” because the 
description of the properties and functions of the air 
or other gas segmentizing medium would suggest to a 
person skilled in the art that appellant’s invention 





includes the use of “inert fluid” broadly.). However, in 
Tronzo v. Biomet, 156 F.3d 1154, 1159, 47 USPQ2d 
1829, 1833 (Fed. Cir. 1998), the disclosure of a species 
in the parent application did not suffice to provide 
written description support for the genus in the child 
application. Similarly, see In re Gosteli, 872 F.2d 
1008, 10 USPQ2d 1614 (Fed. Cir. 1989) (generic and 
subgeneric claims in the U.S. application were not 
entitled to the benefit of foreign priority where the 
foreign application disclosed only two of the 
species 
encompassed by the broad generic claim and 
the subgeneric Markush claim that encompassed 21 
compounds). 

II.NARROWING OR SUBGENERIC CLAIM

The introduction of claim changes which involve 
narrowing the claims by introducing elements or limitations 
which are not supported by the as-filed disclosure 
is a violation of the written description 
requirement of 35 U.S.C. 112, first paragraph. See, 
e.g., Fujikawa v. Wattanasin, 93 F.3d 1559, 1571, 
39 
USPQ2d 1895, 1905 (Fed. Cir. 1996) (a “laundry 
list” disclosure of every possible moiety does not constitute 
a written description of every species in a 
genus because it would not “reasonably lead” those 
skilled in the art to any particular species); In re Ruschig, 
379 F.2d 990, 995, 154 USPQ 118, 123 (CCPA 
1967) (“If n-propylamine had been used in making the 
compound instead of n-butylamine, the compound of 
claim 13 would have resulted. Appellants submit to 
us, as they did to the board, an imaginary specific 
example patterned on specific example 6 by which the 
above butyl compound is made so that we can see 
what a simple change would have resulted in a specific 
supporting disclosure being present in the 
present specification. The trouble is that there is no 
such disclosure, easy though it is to imagine it.”) 
(emphasis in original). In Ex parte Ohshiro, 
14 
USPQ2d 1750 (Bd. Pat. App. & Inter. 1989), the 
Board affirmed the rejection under 35 U.S.C. 112, 
first paragraph, of claims to an internal combustion 
engine which recited “at least one of said piston and 
said cylinder (head) having a recessed channel.” The 
Board held that the application which disclosed a cylinder 
head with a recessed channel and a piston without 
a recessed channel did not specifically disclose 
the “species” of a channeled piston.

While these and other cases find that recitation of 
an undisclosed species may violate the description 
requirement, a change involving subgeneric terminology 
may or may not be acceptable. Applicant was not 
entitled to the benefit of a parent filing date when the 
claim was directed to a subgenus (a specified range of 
molecular weight ratios) where the parent application 
contained a generic disclosure and a specific example 
that fell within the recited range because the court 
held that subgenus range was not described in the parent 
application. In re Lukach, 442 F.2d 967, 
169 
USPQ 795 (CCPA 1971). On the other hand, in 
Ex parte Sorenson, 3 USPQ2d 1462 (Bd. Pat. App. & 
Inter. 1987), the subgeneric language of “aliphatic 
carboxylic acid” and “aryl carboxylic acid” did not 
violate the written description requirement because 
species falling within each subgenus were disclosed 
as well as the generic carboxylic acid. See also In reSmith, 458 F.2d 1389, 1395, 173 USPQ 679, 683 
(CCPA 1972) (“Whatever may be the viability of an 
inductive-deductive approach to arriving at a claimed 
subgenus, it cannot be said that such a subgenus is 
necessarily described by a genus encompassing it and 
a species upon which it reads.” (emphasis added)). 
Each case must be decided on its own facts in terms of 
what is reasonably communicated to those skilled in 
the art. In re Wilder, 736 F.2d 1516, 1520, 222 USPQ 
369, 372 (Fed. Cir. 1984). 

III.RANGE LIMITATIONS

With respect to changing numerical range limitations, 
the analysis must take into account which 
ranges one skilled in the art would consider inherently 
supported by the discussion in the original disclosure. 
In the decision in In re Wertheim, 541 F.2d 257, 
191 
USPQ 90 (CCPA 1976), the ranges described in 
the original specification included a range of “25%- 
60%” and specific examples of “36%” and “50%.” A 
corresponding new claim limitation to “at least 35%” 
did not meet the description requirement because the 
phrase “at least” had no upper limit and caused the 
claim to read literally on embodiments outside the 
“25% to 60%” range, however a limitation to 
“between 35% and 60%” did meet the description 
requirement.

See also Purdue Pharma L.P. v. Faulding Inc., 
230 
F.3d 1320, 1328, 56 USPQ2d 1481, 1487 
(Fed.
Cir. 2000) (“[T]he specification does not clearly 





disclose to the skilled artisan that the inventors... considered 
the... ratio to be part of their invention.... 
There is therefore no force to Purdue’s argument that 
the written description requirement was satisfied 
because the disclosure revealed a broad invention 
from which the [later-filed] claims carved out a patentable 
portion”). Compare Union Oil of Cal. 
v.
Atlantic Richfield Co., 208 F.3d 989, 997, 54 
USPQ2d 1227, 1232-33 (Fed. Cir. 2000) (Description 
in terms of ranges of chemical properties which work 
in combination with ranges of other chemical properties 
to produce an automotive gasoline that reduces 
emissions was found to provide an adequate written 
description even though the exact chemical components 
of each combination were not disclosed and the 
specification did not disclose any distinct embodiments 
corresponding to any claim at issue. “[T]he 
Patent Act and this court’s case law require only sufficient 
description to show one of skill in the . . . art that 
the inventor possessed the claimed invention at the 
time of filing.”).

2163.06Relationship of Written Description 
Requirement to New Matter

Lack of written description is an issue that generally 
arises with respect to the subject matter of a 
claim. If an applicant amends or attempts to amend 
the abstract, specification or drawings of an application, 
an issue of new matter will arise if the content of 
the amendment is not described in the application as 
filed. Stated another way, information contained in 
any one of the specification, claims or drawings of the 
application as filed may be added to any other part of 
the application without introducing new matter.

There are two statutory provisions that prohibit the 
introduction of new matter: 35 U.S.C. 132 - No 
amendment shall introduce new matter into the disclosure 
of the invention; and, similarly providing for a 
reissue application, 35 
U.S.C. 251 - No new matter 
shall be introduced into the application for reissue.

I.TREATMENT OF NEW MATTER

If new subject matter is added to the disclosure, 
whether it be in the abstract, the specification, or the 
drawings, the examiner should object to the introduction 
of new matter under 35 U.S.C. 132 or 251 as 
appropriate, and require applicant to cancel the new 
matter. If new matter is added to the claims, the examiner 
should reject the claims under 35 U.S.C. 112, first 
paragraph - written description requirement. In re 
Rasmussen, 650 F.2d 1212, 211 USPQ 323 (CCPA 
1981). The examiner should still consider the subject 
matter added to the claim in making rejections based 
on prior art since the new matter rejection may be 
overcome by applicant.

In an instance in which the claims have not been 
amended, per se, but the specification has been 
amended to add new matter, a rejection of the claims 
under 35 U.S.C. 112, first paragraph should be made 
whenever any of the claim limitations are affected by 
the added material.

When an amendment is filed in reply to an objection 
or rejection based on 35 U.S.C. 112, first paragraph, 
a study of the entire application is often 
necessary to determine whether or not “new matter” is 
involved. Applicant should therefore specifically 
point out the support for any amendments made to the 
disclosure.

II.REVIEW OF NEW MATTER OBJEC-
TIONS AND/OR REJECTIONS

A rejection of claims is reviewable by the Board of 
Patent Appeals and Interferences, whereas an objection 
and requirement to delete new matter is subject to 
supervisory review by petition under 37 CFR 1.181. If 
both the claims and specification contain new matter 
either directly or indirectly, and there has been both a 
rejection and objection by the examiner, the issue 
becomes appealable and should not be decided by 
petition.

III.CLAIMED SUBJECT MATTER NOT DISCLOSED 
IN REMAINDER OF SPECIFICATION


The claims as filed in the original specification are 
part of the disclosure and therefore, if an application 
as originally filed contains a claim disclosing material 
not disclosed in the remainder of the specification, the 
applicant may amend the specification to include the 
claimed subject matter. In re Benno, 768 F.2d 1340, 
226 USPQ 683 (Fed. Cir. 1985). Form Paragraph 7.44 
may be used where originally claimed subject matter 
lacks proper antecedent basis in the specification. See 
MPEP § 608.01(o).





2163.07Amendments to Application 
Which Are Supported in the 
Original Description [R-3]

Amendments to an application which are supported 
in the original description are NOT new matter.

I.REPHRASING

Mere rephrasing of a passage does not constitute 
new matter. Accordingly, a rewording of a 
passage 
where the same meaning remains intact is 
permissible. In re Anderson, 471 F.2d 1237, 
176 
USPQ 331 (CCPA 1973). The mere inclusion of 
dictionary or art recognized definitions known at the 
time of filing an application would not be considered 
new matter. If there are multiple definitions for a term 
and a definition is added to the application, it must be 
clear from the application as filed that applicant 
intended a particular definition, in order to avoid an 
issue of new matter and/or lack of written description. 
See, e.g., Scarring Corp. v. Megan, Inc., 222 F.3d 
1347, 1352-53, 55 USPQ2d 1650, 1654 (Fed. Cir. 
2000). In Scarring, the original disclosure drawn to 
recombinant DNA molecules utilized the term “leukocyte 
interferon.” Shortly after the filing date, a scientific 
committee abolished the term in favor of “IFN-
(a),” since the latter term more specifically identified 
a particular polypeptide and since the committee 
found that leukocytes also produced other types of 
interferon. The court held that the subsequent amendment 
to the specification and claims substituting the 
term “IFN-(a)” for “leukocyte interferon” merely 
renamed the invention and did not constitute new 
matter. The claims were limited to cover only the 
interferon subtype coded for by the inventor’s original 
deposits.

II.OBVIOUS ERRORS

An amendment to correct an obvious error does not 
constitute new matter where one skilled in the art 
would not only recognize the existence of error in the 
specification, but also the appropriate correction. In reOdd, 443 F.2d 1200, 170 USPQ 268 (CCPA 1971).

Where a foreign priority document under 35 
U.S.C. 
119 is of record in the U.S. application file, applicant 
may not rely on the disclosure of that document to 
support correction of an error in the pending U.S. 
application. Ex parte Bandeau, 132 USPQ 356 (Bd. 
App. 1961). This prohibition applies regardless of the 
language of the foreign priority documents because a 
claim for priority is simply a claim for the benefit of 
an earlier filing date for subject matter that is common 
to two or more applications, and does not serve to 
incorporate the content of the priority document in the 
application in which the claim for priority is made. 
This prohibition does not apply where the U.S. application 
explicitly incorporates the foreign priority document 
by reference. For applications filed on or after 
September 21, 2004, where all or a portion of the 
specification or drawing(s) is inadvertently omitted 
from the U.S. application, a claim under 37 CFR 1.55for priority of a prior-filed foreign application that is 
present on the filing date of the application is considered 
an incorporation by reference of the prior-filed 
foreign application as to the inadvertently omitted 
portion of the specification or drawing(s), subject to 
the conditions and requirements of 37 CFR 1.57(a). 
See 37 CFR 1.57(a) and MPEP § 201.17.

Where a U.S. application as originally filed was in 
a non-English language and an English translation 
thereof was subsequently submitted pursuant to 
37 
CFR 1.52(d), if there is an error in the English 
translation, applicant may rely on the disclosure of the 
originally filed non-English language U.S. application 
to support correction of an error in the English translation 
document.

2163.07(a)Inherent Function, Theory, orAdvantage

By disclosing in a patent application a device that 
inherently performs a function or has a property, operates 
according to a theory or has an advantage, a 
patent application necessarily discloses that function, 
theory or advantage, even though it says nothing 
explicit concerning it. The application may later be 
amended to recite the function, theory or advantage 
without introducing prohibited new matter. In re Reynolds, 
443 F.2d 384, 170 USPQ 94 (CCPA 1971); In 
re Smythe, 480 F. 2d 1376, 178 USPQ 279 (CCPA 
1973). “To establish inherency, the extrinsic evidence 
‘must make clear that the missing descriptive matter 
is necessarily present in the thing described in the reference, 
and that it would be so recognized by persons 
of ordinary skill. Inherency, however, may not be 
established by probabilities or possibilities. The mere 
fact that a certain thing may result from a given set of 





circumstances is not sufficient.’” In re Robertson, 
169 
F.3d 743, 745, 49 USPQ2d 1949, 1950-51 (Fed. 
Cir. 1999) (citations omitted).

2163.07(b)Incorporation by Reference[R-3]

Instead of repeating some information contained in 
another document, an application may attempt to 
incorporate the content of another document or part 
thereof by reference to the document in the text of the 
specification. The information incorporated is as 
much a part of the application as filed as if the text 
was repeated in the application, and should be treated 
as part of the text of the application as filed. Replacing 
the identified material incorporated by reference 
with the actual text is not new matter. See 37 CFR 
1.57 and MPEP §
608.01(p) for Office policy 
regarding incorporation by reference. See MPEP 
§
2181 for the impact of incorporation by reference on 
the determination of whether applicant has complied 
with the requirements of 35 U.S.C. 112, second paragraph 
when 35 U.S.C. 112, sixth paragraph is 
invoked.