Editing MPEP 2124

<noinclude>{{MPEP Section|2123|2100|2125}}</noinclude>

==[[MPEP 2124|2124 Exception to the Rule That the Critical Reference Date Must Precede the Filing Date]]==

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IN SOME CIRCUMSTANCES A FACTUAL REFERENCE 
NEED NOT ANTEDATE THE FILING 
DATE

In certain circumstances, references cited to show a 
universal fact need not be available as prior art before 
applicant’s filing date. In re Wilson, 311 F.2d 266, 
135 
USPQ 442 (CCPA 1962). Such facts include the 
characteristics and properties of a material or a scientific 
truism. Some specific examples in which later 
publications showing factual evidence can be cited 
include situations where the facts shown in the reference 
are evidence “that, as of an application’s filing 
date, undue experimentation would have been 
required, In re Corneil, 347 F.2d 563, 568, 145 USPQ 
702, 705 (CCPA 1965), or that a parameter absent 
from the claims was or was not critical, In re Rainer, 
305 F.2d 505, 507 n.3, 134 USPQ 343, 345 n.3 
(CCPA 1962), or that a statement in the specification 
was inaccurate, In re Marzocchi, 439 F.2d 220, 223 
n.4, 169 USPQ 367, 370 n.4 (CCPA 1971), or that the 
invention was inoperative or lacked utility, In re 
Langer, 503 F.2d 1380, 1391, 183 USPQ 288, 
297 
(CCPA 1974), or that a claim was indefinite, In re 
Glass, 492 F.2d 1228,1232 n.6, 181 USPQ 31, 34 n.6 
(CCPA 1974), or that characteristics of prior art products 
were known, In re Wilson, 311 F.2d 266, 135 
USPQ 442 (CCPA 1962).” In re Koller, 613 F.2d 819, 
823 n.5, 204 
USPQ 702, 706 n.5 (CCPA 1980) (quoting 
In re Hogan, 559 F.2d 595, 605 n.17, 194 USPQ 
527, 537 n.17 (CCPA 1977) (emphasis in original)). 
However, it is impermissible to use a later factual reference 
to determine whether the application is enabled 
or described as required under 35 U.S.C. 112, first 
paragraph. In re Koller, 613 F.2d 819, 823 n. 5, 
204 
USPQ 702, 706 n.5 (CCPA 1980). References 
which do not qualify as prior art because they postdate 
the claimed invention may be relied upon to 
show the level of ordinary skill in the art at or around 
the time the invention was made. Ex parte Erlich, 
22 
USPQ 1463 (Bd. Pat. App. & Inter. 1992).