MPEP § 2124 — Exception to the Rule That the Reference Must be Prior Art (Annotated Rules)

§2124 Exception to the Rule That the Reference Must be Prior Art

USPTO MPEP version: BlueIron's Update: 2026-01-10

This page consolidates and annotates all enforceable requirements under MPEP § 2124, including statutory authority, regulatory rules, examiner guidance, and practice notes. It is provided as guidance, with links to the ground truth sources. This is information only, it is not legal advice.

Exception to the Rule That the Reference Must be Prior Art

This section addresses Exception to the Rule That the Reference Must be Prior Art. Primary authority: 35 U.S.C. 112(a) and 35 U.S.C. 112. Contains: 1 requirement, 1 permission, and 4 other statements.

Key Rules

Topic

Scope Commensurate with Disclosure

3 rules
StatutoryRequiredAlways
[mpep-2124-8fdab84795cb2e271689c4c9]
Use of Post-Filing Date Evidence for Enablement
Note:
This rule permits the use of post-filing date evidence to show that a patent fails to disclose a representative number of species or requires undue experimentation, but prohibits using such evidence to determine enablement under section 112(a).

In certain circumstances, references cited to show a universal fact need not be available as prior art before the effective filing date of applicant’s claimed invention. 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, 824 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)). See also Amgen Inc. v. Sanofi, 872 F.3d 1367, 1375, 124 USPQ2d 1354, 1359 (Fed. Cir. 2017)(post-effective-filing-date evidence could be relied upon to show that patent failed to disclose a representative number of species of a claimed genus, and to show that patentees may have engaged in undue experimentation to enable the full scope of the claims before the effective filing date). However, it is impermissible to use a later factual reference showing the state of the art existing after the effective filing date of the claimed invention to determine whether the application is enabled or described as required under 35 U.S.C. 112(a) or pre-AIA 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). Post-effective-filing-date evidence offered to illuminate the post-effective-filing-date state of the art is improper. Amgen, 872 F.3d at 1374, 124 USPQ2d at 1359. 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 relevant time. See Ex parte Erlich, 22 USPQ2d 1463 (Bd. Pat. App. & Inter. 1992).

Jump to MPEP SourceScope Commensurate with DisclosureUndue ExperimentationInoperative Subject Matter (MPEP 2164.08(b))
StatutoryInformativeAlways
[mpep-2124-953d1cd7e4e3ce90b4b28597]
Post-Effective-Filing-Date Evidence for Inoperability
Note:
This rule permits using post-filing date evidence to show that a patent is inoperative or lacks utility, but not for enablement or description under 35 U.S.C. 112.

In certain circumstances, references cited to show a universal fact need not be available as prior art before the effective filing date of applicant’s claimed invention. 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, 824 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)). See also Amgen Inc. v. Sanofi, 872 F.3d 1367, 1375, 124 USPQ2d 1354, 1359 (Fed. Cir. 2017)(post-effective-filing-date evidence could be relied upon to show that patent failed to disclose a representative number of species of a claimed genus, and to show that patentees may have engaged in undue experimentation to enable the full scope of the claims before the effective filing date). However, it is impermissible to use a later factual reference showing the state of the art existing after the effective filing date of the claimed invention to determine whether the application is enabled or described as required under 35 U.S.C. 112(a) or pre-AIA 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). Post-effective-filing-date evidence offered to illuminate the post-effective-filing-date state of the art is improper. Amgen, 872 F.3d at 1374, 124 USPQ2d at 1359. 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 relevant time. See Ex parte Erlich, 22 USPQ2d 1463 (Bd. Pat. App. & Inter. 1992).

Jump to MPEP SourceScope Commensurate with DisclosureUndue ExperimentationInoperative Subject Matter (MPEP 2164.08(b))
StatutoryInformativeAlways
[mpep-2124-3237f3035bbb3a921f0a10d1]
Post-Effective-Filing-Date Evidence Not for Enablement
Note:
The rule prohibits using post-filing date evidence to determine if an invention is enabled under 35 U.S.C. 112(a).

In certain circumstances, references cited to show a universal fact need not be available as prior art before the effective filing date of applicant’s claimed invention. 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, 824 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)). See also Amgen Inc. v. Sanofi, 872 F.3d 1367, 1375, 124 USPQ2d 1354, 1359 (Fed. Cir. 2017)(post-effective-filing-date evidence could be relied upon to show that patent failed to disclose a representative number of species of a claimed genus, and to show that patentees may have engaged in undue experimentation to enable the full scope of the claims before the effective filing date). However, it is impermissible to use a later factual reference showing the state of the art existing after the effective filing date of the claimed invention to determine whether the application is enabled or described as required under 35 U.S.C. 112(a) or pre-AIA 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). Post-effective-filing-date evidence offered to illuminate the post-effective-filing-date state of the art is improper. Amgen, 872 F.3d at 1374, 124 USPQ2d at 1359. 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 relevant time. See Ex parte Erlich, 22 USPQ2d 1463 (Bd. Pat. App. & Inter. 1992).

Jump to MPEP SourceScope Commensurate with DisclosureUndue ExperimentationInoperative Subject Matter (MPEP 2164.08(b))
Topic

State of the Prior Art (Wands Factor)

2 rules
StatutoryInformativeAlways
[mpep-2124-089773231985e326ccb554b7]
Post-Effective Filing Date Evidence for State of the Art
Note:
The rule permits using post-filing date references to establish the state of the art, but not for determining enablement or written description under section 112(a).

In certain circumstances, references cited to show a universal fact need not be available as prior art before the effective filing date of applicant’s claimed invention. 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, 824 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)). See also Amgen Inc. v. Sanofi, 872 F.3d 1367, 1375, 124 USPQ2d 1354, 1359 (Fed. Cir. 2017)(post-effective-filing-date evidence could be relied upon to show that patent failed to disclose a representative number of species of a claimed genus, and to show that patentees may have engaged in undue experimentation to enable the full scope of the claims before the effective filing date). However, it is impermissible to use a later factual reference showing the state of the art existing after the effective filing date of the claimed invention to determine whether the application is enabled or described as required under 35 U.S.C. 112(a) or pre-AIA 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). Post-effective-filing-date evidence offered to illuminate the post-effective-filing-date state of the art is improper. Amgen, 872 F.3d at 1374, 124 USPQ2d at 1359. 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 relevant time. See Ex parte Erlich, 22 USPQ2d 1463 (Bd. Pat. App. & Inter. 1992).

Jump to MPEP SourceState of the Prior Art (Wands Factor)Determining Whether Application Is AIA or Pre-AIAAlternative Limitations (MPEP 2173.05(h))
StatutoryInformativeAlways
[mpep-2124-be40b6bb62ed488831df9b01]
Post-Effective-Filing-State of the Art Evidence Is Improper
Note:
The rule prohibits using evidence after the effective filing date to determine if an application is enabled or described under section 112(a).

In certain circumstances, references cited to show a universal fact need not be available as prior art before the effective filing date of applicant’s claimed invention. 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, 824 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)). See also Amgen Inc. v. Sanofi, 872 F.3d 1367, 1375, 124 USPQ2d 1354, 1359 (Fed. Cir. 2017)(post-effective-filing-date evidence could be relied upon to show that patent failed to disclose a representative number of species of a claimed genus, and to show that patentees may have engaged in undue experimentation to enable the full scope of the claims before the effective filing date). However, it is impermissible to use a later factual reference showing the state of the art existing after the effective filing date of the claimed invention to determine whether the application is enabled or described as required under 35 U.S.C. 112(a) or pre-AIA 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). Post-effective-filing-date evidence offered to illuminate the post-effective-filing-date state of the art is improper. Amgen, 872 F.3d at 1374, 124 USPQ2d at 1359. 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 relevant time. See Ex parte Erlich, 22 USPQ2d 1463 (Bd. Pat. App. & Inter. 1992).

Jump to MPEP SourceState of the Prior Art (Wands Factor)Lack of Antecedent Basis (MPEP 2173.05(e))Scope Commensurate with Disclosure
Topic

Level of Ordinary Skill (Wands Factor)

1 rules
StatutoryPermittedAlways
[mpep-2124-7b4805d98fe7eda57e8051e1]
References Showing Art Level at Relevant Time
Note:
References postdating the claimed invention can be used to show the level of ordinary skill in the art at or around the relevant time.

In certain circumstances, references cited to show a universal fact need not be available as prior art before the effective filing date of applicant’s claimed invention. 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, 824 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)). See also Amgen Inc. v. Sanofi, 872 F.3d 1367, 1375, 124 USPQ2d 1354, 1359 (Fed. Cir. 2017)(post-effective-filing-date evidence could be relied upon to show that patent failed to disclose a representative number of species of a claimed genus, and to show that patentees may have engaged in undue experimentation to enable the full scope of the claims before the effective filing date). However, it is impermissible to use a later factual reference showing the state of the art existing after the effective filing date of the claimed invention to determine whether the application is enabled or described as required under 35 U.S.C. 112(a) or pre-AIA 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). Post-effective-filing-date evidence offered to illuminate the post-effective-filing-date state of the art is improper. Amgen, 872 F.3d at 1374, 124 USPQ2d at 1359. 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 relevant time. See Ex parte Erlich, 22 USPQ2d 1463 (Bd. Pat. App. & Inter. 1992).

Jump to MPEP SourceLevel of Ordinary Skill (Wands Factor)State of the Prior Art (Wands Factor)Determining Whether Application Is AIA or Pre-AIA

Citations

Primary topicCitation
Level of Ordinary Skill (Wands Factor)
Scope Commensurate with Disclosure
State of the Prior Art (Wands Factor)
35 U.S.C. § 112
Level of Ordinary Skill (Wands Factor)
Scope Commensurate with Disclosure
State of the Prior Art (Wands Factor)
35 U.S.C. § 112(a)
Level of Ordinary Skill (Wands Factor)
Scope Commensurate with Disclosure
State of the Prior Art (Wands Factor)
In re Corneil, 347 F.2d 563, 568, 145 USPQ 702, 705 (CCPA 1965)
Level of Ordinary Skill (Wands Factor)
Scope Commensurate with Disclosure
State of the Prior Art (Wands Factor)
In re Langer, 503 F.2d 1380, 1391, 183 USPQ 288, 297 (CCPA 1974)
Level of Ordinary Skill (Wands Factor)
Scope Commensurate with Disclosure
State of the Prior Art (Wands Factor)
In re Wilson, 311 F.2d 266, 135 USPQ 442 (CCPA 1962)
Level of Ordinary Skill (Wands Factor)
Scope Commensurate with Disclosure
State of the Prior Art (Wands Factor)
See also Amgen Inc. v. Sanofi, 872 F.3d 1367, 1375, 124 USPQ2d 1354, 1359 (Fed. Cir. 2017)

Source Text from USPTO’s MPEP

This is an exact copy of the MPEP from the USPTO. It is here for your reference to see the section in context.

BlueIron Last Updated: 2026-01-10