MPEP 2164.02
Working and Prophetic Examples

Ninth Edition of the MPEP, Revision 07.2022, Last Revised in February 2023

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2164.02    Working and Prophetic Examples [R-07.2022]

Compliance with the enablement requirement of 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, does not turn on whether an example is disclosed. An example may be "working" or "prophetic." A working example is based on work actually performed. A prophetic example describes an embodiment of the invention based on predicted results rather than work actually conducted or results actually achieved. The claims should be drafted in a manner that assists readers in differentiating between actual working examples and prophetic examples (i.e., prophetic examples should not be described using the past tense, but rather in future or present tense).

An applicant need not have actually reduced the invention to practice prior to filing. In Gould v. Quigg, 822 F.2d 1074, 1078, 3 USPQ 2d 1302, 1304 (Fed. Cir. 1987), as of Gould’s filing date, no person had built a light amplifier or measured a population inversion in a gas discharge. The court held that "The mere fact that something has not previously been done clearly is not, in itself, a sufficient basis for rejecting all applications purporting to disclose how to do it." 822 F.2d at 1078, 3 USPQ2d at 1304 (quoting In re Chilowsky, 229 F.2d 457, 461, 108 USPQ 321, 325 (CCPA 1956)).

The specification need not contain an example if the invention is otherwise disclosed in such manner that one skilled in the art will be able to practice it without an undue amount of experimentation. In re Borkowski, 422 F.2d 904, 908, 164 USPQ 642, 645 (CCPA 1970). Allergan, Inc. v. Sandoz Inc., 796 F.3d 1293, 1310, 115 USPQ2d 2012, 2023 (Fed. Cir. 2015) ( "Only a sufficient description enabling a person of ordinary skill in the art to carry out an invention is needed."). Lack of a working example, however, is a factor to be considered, especially in a case involving an unpredictable and undeveloped art. But because only an enabling disclosure is required, applicant need not describe all actual embodiments.

The courts have further cautioned that the presence of prophetic examples alone should not be the basis for asserting that a specification is not enabling; rather, a lack of operative embodiments and undue experimentation should be determinative. Atlas Powder Co. v. E.I. du Pont De Nemours & Co., 750 F.2d 1569, 1577, 224 USPQ 409, 414 (Fed. Cir. 1984).


When considering the factors relating to a determination of non-enablement, if all the other factors point toward enablement, then the absence of working examples will not by itself render the invention non-enabled. In other words, lack of working examples or lack of evidence that the claimed invention works as described should never be the sole reason for rejecting the claimed invention on the grounds of lack of enablement. A single working example in the specification for a claimed invention is enough to preclude a rejection which states that nothing is enabled since at least that embodiment would be enabled. However, a rejection stating that enablement is limited to a particular scope may be appropriate.

The presence of only one working example should never be the sole reason for rejecting claims as being broader than the enabling disclosure, even though it is a factor to be considered along with all the other factors. To make a valid rejection, the examiner must evaluate all the facts and evidence and state why one would not expect to be able to extrapolate that one example across the entire scope of the claims.


The issue of "correlation" is related to the issue of the presence or absence of working examples. "Correlation" as used herein refers to the relationship between in vitro or in vivo animal model assays and a disclosed or a claimed method of use. An in vitro or in vivo animal model example in the specification, in effect, constitutes a "working example" if that example "correlates" with a disclosed or claimed method invention. If there is no correlation, then the examples do not constitute "working examples." In this regard, the issue of "correlation" is also dependent on the state of the prior art. In other words, if the art is such that a particular model is recognized as correlating to a specific condition, then it should be accepted as correlating unless the examiner has evidence that the model does not correlate. Even with such evidence, the examiner must weigh the evidence for and against correlation and decide whether one skilled in the art would accept the model as reasonably correlating to the condition. In re Brana, 51 F.3d 1560, 1566, 34 USPQ2d 1436, 1441 (Fed. Cir. 1995) (reversing a USPTO decision based on finding that in vitro data did not support in vivo applications).

Since the initial burden is on the examiner to give reasons for the lack of enablement, the examiner must also give reasons for a conclusion of lack of correlation for an in vitro or in vivo animal model example. However, a rigorous or an invariable exact correlation is not required, as stated in Cross v. Iizuka, 753 F.2d 1040, 1050, 224 USPQ 739, 747 (Fed. Cir. 1985):

[B]ased upon the relevant evidence as a whole, there is a reasonable correlation between the disclosed in vitro utility and an in vivo activity, and therefore a rigorous correlation is not necessary where the disclosure of pharmacological activity is reasonable based upon the probative evidence. (Citations omitted.)


For a claimed genus, representative examples together with a statement applicable to the genus as a whole will ordinarily be sufficient if one skilled in the art (in view of level of skill, state of the art and the information in the specification) would expect the claimed genus could be used in that manner without undue experimentation. Proof of enablement will be required for other members of the claimed genus only where adequate reasons are advanced by the examiner to establish that a person skilled in the art could not use the genus as a whole without undue experimentation.


When prophetic examples are described in a manner that is ambiguous or that implies that the results are actual, the adequacy and accuracy of the disclosure may come into question. If the characterization of the results, when taken in light of the disclosure as a whole, reasonably raises any questions as to whether the results from the examples are actual, the examiner should determine whether to reject the appropriate claims based on an insufficient disclosure under the enablement and/or written description requirements of 35 U.S.C. 112(a) following the guidance in MPEP §§ 2164 and 2163, respectively. When such a rejection(s) is made, the applicant should reply with the results of an actual test or example that has been conducted, or by providing relevant arguments and/or declaration evidence that there is strong reason to believe that the result would be as predicted, being careful not to introduce new matter into the application. See Hoffmann-La Roche, Inc. v. Promega Corp., 323 F.3d. 1354, 1367, 66 USPQ2d 1385, 1394 (Fed. Cir. 2003) (improperly identifying a prophetic example in the past tense validly raises an inequitable conduct issue based on the intent of the inventors in drafting the example in the past tense, when the example, in fact, is prophetic); and Apotex Inc. v. UCB, Inc., 763 F.3d 1354, 1362, 112 USPQ2d 1081, 1087 (Fed. Cir. 2014) (the inventor "admitted that he never performed the experiments described in the... patent, and yet he drafted the examples in the specification entirely in past-tense language."). No results should be represented as actual results unless they have actually been achieved. See MPEP § 2004, item 8.