MPEP § 2163.03 — Typical Circumstances Where Adequate Written Description Issue Arises (Annotated Rules)

§2163.03 Typical Circumstances Where Adequate Written Description Issue Arises

USPTO MPEP version: BlueIron's Update: 2025-12-31

This page consolidates and annotates all enforceable requirements under MPEP § 2163.03, 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.

Typical Circumstances Where Adequate Written Description Issue Arises

This section addresses Typical Circumstances Where Adequate Written Description Issue Arises. Primary authority: 35 U.S.C. 120, 35 U.S.C. 112(a), and 35 U.S.C. 112. Contains: 1 requirement, 1 permission, and 13 other statements.

Key Rules

Topic

PTAB Jurisdiction

9 rules
StatutoryInformativeAlways
[mpep-2163-03-9e8eb924d0f9d5aa301a2ce1]
Claims Entitled to Earlier Filing Date Under 35 U.S.C. 120
Note:
Claims in a U.S. application are entitled to the filing date of an earlier filed U.S. application if the subject matter is disclosed according to 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph.

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(a) or pre-AIA 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 re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978). See also Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 2023 USPQ2d 269 (Fed. Cir. 2023). The court noted that the Board evaluated whether the earlier- filed applications provided an “ ipsis verbis ” disclosure of the claimed subgenus. In reviewing this evaluation, the court agreed with the Board that the earlier-filed applications recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Id. at 1357. Thus, it was unclear how many compounds actually fell within the described genera and subgenera. Id. The court also noted that the Board then evaluated whether the prior applications “provided sufficient blaze marks to provide written description support for the ‘830 patent claims.” Id. at 1357. The court agreed with the Board that there were no adequate blaze marks. Id. at 1358. Therefore, the court held that the earlier-filed applications did not provide sufficient written description to support the later-filed patent claims under 35 U.S.C. 120.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case Procedures35 U.S.C. 112(a) – Written Description & Enablement
StatutoryInformativeAlways
[mpep-2163-03-088fb4483d9d40e0cc77d4e5]
Claims Must Be Supported by Earlier Application Disclosure
Note:
The claims in a U.S. application must be supported by the written description of an earlier-filed U.S. 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(a) or pre-AIA 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 re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978). See also Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 2023 USPQ2d 269 (Fed. Cir. 2023). The court noted that the Board evaluated whether the earlier- filed applications provided an “ ipsis verbis ” disclosure of the claimed subgenus. In reviewing this evaluation, the court agreed with the Board that the earlier-filed applications recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Id. at 1357. Thus, it was unclear how many compounds actually fell within the described genera and subgenera. Id. The court also noted that the Board then evaluated whether the prior applications “provided sufficient blaze marks to provide written description support for the ‘830 patent claims.” Id. at 1357. The court agreed with the Board that there were no adequate blaze marks. Id. at 1358. Therefore, the court held that the earlier-filed applications did not provide sufficient written description to support the later-filed patent claims under 35 U.S.C. 120.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresWritten Description Requirement (MPEP 2163)
StatutoryInformativeAlways
[mpep-2163-03-2ffc2721bd5e980c8f737520]
Earlier Filed Applications Must Provide Verbatim Disclosure
Note:
The court requires that earlier-filed applications must provide a verbatim disclosure of the claimed subgenus to support later-filed patent claims 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(a) or pre-AIA 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 re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978). See also Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 2023 USPQ2d 269 (Fed. Cir. 2023). The court noted that the Board evaluated whether the earlier- filed applications provided an “ ipsis verbis ” disclosure of the claimed subgenus. In reviewing this evaluation, the court agreed with the Board that the earlier-filed applications recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Id. at 1357. Thus, it was unclear how many compounds actually fell within the described genera and subgenera. Id. The court also noted that the Board then evaluated whether the prior applications “provided sufficient blaze marks to provide written description support for the ‘830 patent claims.” Id. at 1357. The court agreed with the Board that there were no adequate blaze marks. Id. at 1358. Therefore, the court held that the earlier-filed applications did not provide sufficient written description to support the later-filed patent claims under 35 U.S.C. 120.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresJudicial Review of Board Decisions
StatutoryInformativeAlways
[mpep-2163-03-d1c3702eab507e513fc8f860]
Earlier Applications Must Provide Sufficient Disclosure
Note:
The earlier-filed applications must provide a detailed and sufficient disclosure to support the later-filed patent claims 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(a) or pre-AIA 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 re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978). See also Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 2023 USPQ2d 269 (Fed. Cir. 2023). The court noted that the Board evaluated whether the earlier- filed applications provided an “ ipsis verbis ” disclosure of the claimed subgenus. In reviewing this evaluation, the court agreed with the Board that the earlier-filed applications recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Id. at 1357. Thus, it was unclear how many compounds actually fell within the described genera and subgenera. Id. The court also noted that the Board then evaluated whether the prior applications “provided sufficient blaze marks to provide written description support for the ‘830 patent claims.” Id. at 1357. The court agreed with the Board that there were no adequate blaze marks. Id. at 1358. Therefore, the court held that the earlier-filed applications did not provide sufficient written description to support the later-filed patent claims under 35 U.S.C. 120.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresJudicial Review of Board Decisions
StatutoryInformativeAlways
[mpep-2163-03-ca1bc52314b86e6b017aa915]
Insufficient Genera and Subgenera Disclosure
Note:
The earlier-filed applications did not provide sufficient written description to support the later-filed patent claims, as it was unclear how many compounds fell within the described genera and subgenera.

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(a) or pre-AIA 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 re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978). See also Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 2023 USPQ2d 269 (Fed. Cir. 2023). The court noted that the Board evaluated whether the earlier- filed applications provided an “ ipsis verbis ” disclosure of the claimed subgenus. In reviewing this evaluation, the court agreed with the Board that the earlier-filed applications recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Id. at 1357. Thus, it was unclear how many compounds actually fell within the described genera and subgenera. Id. The court also noted that the Board then evaluated whether the prior applications “provided sufficient blaze marks to provide written description support for the ‘830 patent claims.” Id. at 1357. The court agreed with the Board that there were no adequate blaze marks. Id. at 1358. Therefore, the court held that the earlier-filed applications did not provide sufficient written description to support the later-filed patent claims under 35 U.S.C. 120.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresWritten Description Requirement (MPEP 2163)
StatutoryInformativeAlways
[mpep-2163-03-c18efa00445539c144b46ca5]
Prior Applications Must Provide Blaze Marks for Written Description Support
Note:
The court ruled that prior applications must provide specific blaze marks to support the written description of later-filed patent claims 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(a) or pre-AIA 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 re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978). See also Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 2023 USPQ2d 269 (Fed. Cir. 2023). The court noted that the Board evaluated whether the earlier- filed applications provided an “ ipsis verbis ” disclosure of the claimed subgenus. In reviewing this evaluation, the court agreed with the Board that the earlier-filed applications recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Id. at 1357. Thus, it was unclear how many compounds actually fell within the described genera and subgenera. Id. The court also noted that the Board then evaluated whether the prior applications “provided sufficient blaze marks to provide written description support for the ‘830 patent claims.” Id. at 1357. The court agreed with the Board that there were no adequate blaze marks. Id. at 1358. Therefore, the court held that the earlier-filed applications did not provide sufficient written description to support the later-filed patent claims under 35 U.S.C. 120.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresWritten Description Requirement (MPEP 2163)
StatutoryInformativeAlways
[mpep-2163-03-60b17b297354bdc8ea144056]
Claims Must Be Supported by Earlier Application Disclosure
Note:
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 is disclosed in the manner provided by 35 U.S.C. 112(a) or pre-AIA 112, first paragraph.

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(a) or pre-AIA 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 re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978). See also Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 2023 USPQ2d 269 (Fed. Cir. 2023). The court noted that the Board evaluated whether the earlier- filed applications provided an “ ipsis verbis ” disclosure of the claimed subgenus. In reviewing this evaluation, the court agreed with the Board that the earlier-filed applications recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Id. at 1357. Thus, it was unclear how many compounds actually fell within the described genera and subgenera. Id. The court also noted that the Board then evaluated whether the prior applications “provided sufficient blaze marks to provide written description support for the ‘830 patent claims.” Id. at 1357. The court agreed with the Board that there were no adequate blaze marks. Id. at 1358. Therefore, the court held that the earlier-filed applications did not provide sufficient written description to support the later-filed patent claims under 35 U.S.C. 120.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresWritten Description Requirement (MPEP 2163)
StatutoryInformativeAlways
[mpep-2163-03-1a54550ca1ad7ccb5942fc2d]
No Adequate Blaze Marks for Written Description Support
Note:
The court agreed that the earlier-filed applications did not provide sufficient blaze marks to support the later-filed patent claims 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(a) or pre-AIA 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 re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978). See also Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 2023 USPQ2d 269 (Fed. Cir. 2023). The court noted that the Board evaluated whether the earlier- filed applications provided an “ ipsis verbis ” disclosure of the claimed subgenus. In reviewing this evaluation, the court agreed with the Board that the earlier-filed applications recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Id. at 1357. Thus, it was unclear how many compounds actually fell within the described genera and subgenera. Id. The court also noted that the Board then evaluated whether the prior applications “provided sufficient blaze marks to provide written description support for the ‘830 patent claims.” Id. at 1357. The court agreed with the Board that there were no adequate blaze marks. Id. at 1358. Therefore, the court held that the earlier-filed applications did not provide sufficient written description to support the later-filed patent claims under 35 U.S.C. 120.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresJudicial Review of Board Decisions
StatutoryInformativeAlways
[mpep-2163-03-3f4ee2389dda96a8b3b65b77]
Earlier Filed Applications Must Provide Sufficient Written Description for Later Claims
Note:
The earlier-filed applications must provide a sufficient written description to support the later-filed patent claims 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(a) or pre-AIA 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 re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978). See also Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 2023 USPQ2d 269 (Fed. Cir. 2023). The court noted that the Board evaluated whether the earlier- filed applications provided an “ ipsis verbis ” disclosure of the claimed subgenus. In reviewing this evaluation, the court agreed with the Board that the earlier-filed applications recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Id. at 1357. Thus, it was unclear how many compounds actually fell within the described genera and subgenera. Id. The court also noted that the Board then evaluated whether the prior applications “provided sufficient blaze marks to provide written description support for the ‘830 patent claims.” Id. at 1357. The court agreed with the Board that there were no adequate blaze marks. Id. at 1358. Therefore, the court held that the earlier-filed applications did not provide sufficient written description to support the later-filed patent claims under 35 U.S.C. 120.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresWritten Description Requirement (MPEP 2163)
Topic

Written Description Requirement (MPEP 2163)

3 rules
StatutoryInformativeAlways
[mpep-2163-03-a766c8e05a64e68a4efbcd70]
Claims Must Be Supported by Corresponding Foreign Application
Note:
Claims in a U.S. application must be supported by the corresponding foreign application under 35 U.S.C. 119(a) or (e).

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(a) or pre-AIA 35 U.S.C. 112, first paragraph. Purdue Pharma LP v. Iancu, 767 Fed. Appx. 918, 923-24, 2019 USPQ2d 136363 (Fed. Cir. 2019); 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).

Jump to MPEP SourceWritten Description Requirement (MPEP 2163)Foreign Priority ClaimsProvisional Application Benefit
StatutoryRequiredAlways
[mpep-2163-03-351bd93ccb2ab09485b8cdee]
Claims Must Be Supported by Specification
Note:
In an interference proceeding, claims must be supported by the specification in accordance with 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph.

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(a) or pre-AIA 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(a) or pre-AIA 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).

Jump to MPEP SourceWritten Description Requirement (MPEP 2163)35 U.S.C. 112(a) – Written Description & EnablementAIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2163-03-567f51e6005439853a542779]
Claim Limitation Must Be Supported by Structure
Note:
A claim using means-plus-function language must be supported by corresponding structure in the specification to avoid indefiniteness and lack of written description.

A claim limitation expressed in means- (or step-) plus-function language “shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.” 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph. If the specification fails to disclose sufficient corresponding structure, materials, or acts that perform the entire claimed function, then the claim limitation is indefinite because the applicant has in effect failed to particularly point out and distinctly claim the invention as required by 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. In re Donaldson Co., 16 F.3d 1189, 1195, 29 USPQ2d 1845, 1850 (Fed. Cir. 1994) (en banc). Such a limitation also lacks an adequate written description as required by 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, because an indefinite, unbounded functional limitation would cover all ways of performing a function and indicate that the inventor has not provided sufficient disclosure to show possession of the invention. See also MPEP § 2181.

Jump to MPEP SourceWritten Description Requirement (MPEP 2163)Possession of the Invention (MPEP 2163.02)Missing Information – Enablement (MPEP 2164.06(a))
Topic

Claim Form Requirements

3 rules
StatutoryInformativeAlways
[mpep-2163-03-efb294a8973062a4368e2cae]
Original Claim Must Be Supported By Specification
Note:
An original claim must be supported by the specification, especially if it defines the invention in functional language or presents a broad genus without describing relevant species.

While there is a 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), a question as to whether a specification provides an adequate written description may arise in the context of an original claim. An original claim may lack written description support when (1) the claim defines the invention in functional language specifying a desired result but the disclosure fails to sufficiently identify how the function is performed or the result is achieved or (2) a broad genus claim is presented but the disclosure only describes a narrow species with no evidence that the genus is contemplated. See Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1349-50 (Fed. Cir. 2010) (en banc). The written description requirement is not necessarily met when the claim language appears in ipsis verbis in the specification. “Even if a claim is supported by the specification, the language of the specification, to the extent possible, must describe the claimed invention so that one skilled in the art can recognize what is claimed. The appearance of mere indistinct words in a specification or a claim, even an original claim, does not necessarily satisfy that requirement.” Enzo Biochem, Inc. v. Gen-Probe, Inc., 323 F.3d 956, 968, 63 USPQ2d 1609, 1616 (Fed. Cir. 2002).

Jump to MPEP SourceClaim Form RequirementsOptional Claim ContentGenus and Species Claims
StatutoryInformativeAlways
[mpep-2163-03-bb81506ea34aa719e7129463]
Claim Language Not Necessarily Meets Written Description
Note:
The written description requirement is satisfied even if the claim language appears verbatim in the specification.

While there is a 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), a question as to whether a specification provides an adequate written description may arise in the context of an original claim. An original claim may lack written description support when (1) the claim defines the invention in functional language specifying a desired result but the disclosure fails to sufficiently identify how the function is performed or the result is achieved or (2) a broad genus claim is presented but the disclosure only describes a narrow species with no evidence that the genus is contemplated. See Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1349-50 (Fed. Cir. 2010) (en banc). The written description requirement is not necessarily met when the claim language appears in ipsis verbis in the specification. “Even if a claim is supported by the specification, the language of the specification, to the extent possible, must describe the claimed invention so that one skilled in the art can recognize what is claimed. The appearance of mere indistinct words in a specification or a claim, even an original claim, does not necessarily satisfy that requirement.” Enzo Biochem, Inc. v. Gen-Probe, Inc., 323 F.3d 956, 968, 63 USPQ2d 1609, 1616 (Fed. Cir. 2002).

Jump to MPEP SourceClaim Form RequirementsPatent Application Content
StatutoryInformativeAlways
[mpep-2163-03-d9e9c00ff9c0d7c89bba4f84]
Claim Must Be Supported by Written Description
Note:
A claim must be supported by a written description that adequately describes the invention, even if the language appears in the specification.

While there is a 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), a question as to whether a specification provides an adequate written description may arise in the context of an original claim. An original claim may lack written description support when (1) the claim defines the invention in functional language specifying a desired result but the disclosure fails to sufficiently identify how the function is performed or the result is achieved or (2) a broad genus claim is presented but the disclosure only describes a narrow species with no evidence that the genus is contemplated. See Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1349-50 (Fed. Cir. 2010) (en banc). The written description requirement is not necessarily met when the claim language appears in ipsis verbis in the specification. “Even if a claim is supported by the specification, the language of the specification, to the extent possible, must describe the claimed invention so that one skilled in the art can recognize what is claimed. The appearance of mere indistinct words in a specification or a claim, even an original claim, does not necessarily satisfy that requirement.” Enzo Biochem, Inc. v. Gen-Probe, Inc., 323 F.3d 956, 968, 63 USPQ2d 1609, 1616 (Fed. Cir. 2002).

Jump to MPEP SourceClaim Form RequirementsOptional Claim ContentGenus and Species Claims
Topic

Original Claims and New Matter

2 rules
StatutoryPermittedAlways
[mpep-2163-03-5d6679e0a9ff2515232fac1d]
Original Claim Must Describe Invention Adequately
Note:
An original claim must provide a complete description of the invention to support its claims, avoiding functional language without specific implementation details or broad genus claims lacking species examples.

While there is a 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), a question as to whether a specification provides an adequate written description may arise in the context of an original claim. An original claim may lack written description support when (1) the claim defines the invention in functional language specifying a desired result but the disclosure fails to sufficiently identify how the function is performed or the result is achieved or (2) a broad genus claim is presented but the disclosure only describes a narrow species with no evidence that the genus is contemplated. See Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1349-50 (Fed. Cir. 2010) (en banc). The written description requirement is not necessarily met when the claim language appears in ipsis verbis in the specification. “Even if a claim is supported by the specification, the language of the specification, to the extent possible, must describe the claimed invention so that one skilled in the art can recognize what is claimed. The appearance of mere indistinct words in a specification or a claim, even an original claim, does not necessarily satisfy that requirement.” Enzo Biochem, Inc. v. Gen-Probe, Inc., 323 F.3d 956, 968, 63 USPQ2d 1609, 1616 (Fed. Cir. 2002).

Jump to MPEP SourceOriginal Claims and New MatterPatent Application Content
StatutoryInformativeAlways
[mpep-2163-03-2c0c44bc55569cde6bb12b49]
Original Claim Must Be Described
Note:
An original claim must be adequately described in the specification to satisfy the written description requirement, even if the language appears verbatim.

While there is a 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), a question as to whether a specification provides an adequate written description may arise in the context of an original claim. An original claim may lack written description support when (1) the claim defines the invention in functional language specifying a desired result but the disclosure fails to sufficiently identify how the function is performed or the result is achieved or (2) a broad genus claim is presented but the disclosure only describes a narrow species with no evidence that the genus is contemplated. See Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1349-50 (Fed. Cir. 2010) (en banc). The written description requirement is not necessarily met when the claim language appears in ipsis verbis in the specification. “Even if a claim is supported by the specification, the language of the specification, to the extent possible, must describe the claimed invention so that one skilled in the art can recognize what is claimed. The appearance of mere indistinct words in a specification or a claim, even an original claim, does not necessarily satisfy that requirement.” Enzo Biochem, Inc. v. Gen-Probe, Inc., 323 F.3d 956, 968, 63 USPQ2d 1609, 1616 (Fed. Cir. 2002).

Jump to MPEP SourceOriginal Claims and New MatterPatent Application Content
Topic

Claims

2 rules
StatutoryRequiredAlways
[mpep-2163-03-46668de5fd36b12dae3e4b85]
Specification Must Describe Invention Clearly
Note:
The specification must describe the claimed invention in detail so that a skilled artisan can recognize what is claimed, even if the claim is supported by the specification.

While there is a 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), a question as to whether a specification provides an adequate written description may arise in the context of an original claim. An original claim may lack written description support when (1) the claim defines the invention in functional language specifying a desired result but the disclosure fails to sufficiently identify how the function is performed or the result is achieved or (2) a broad genus claim is presented but the disclosure only describes a narrow species with no evidence that the genus is contemplated. See Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1349-50 (Fed. Cir. 2010) (en banc). The written description requirement is not necessarily met when the claim language appears in ipsis verbis in the specification. “Even if a claim is supported by the specification, the language of the specification, to the extent possible, must describe the claimed invention so that one skilled in the art can recognize what is claimed. The appearance of mere indistinct words in a specification or a claim, even an original claim, does not necessarily satisfy that requirement.” Enzo Biochem, Inc. v. Gen-Probe, Inc., 323 F.3d 956, 968, 63 USPQ2d 1609, 1616 (Fed. Cir. 2002).

Jump to MPEP SourcePatent Application ContentClaim Form Requirements
MPEP GuidancePermittedAlways
[mpep-2163-03-a6700ec311f06d1f96426afb]
Amendment to Specification Can Affect Claims Indirectly
Note:
An amendment to the specification, such as changing a term used in both the specification and claims, can indirectly impact the claims even if no direct claim amendment is made.

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.

Jump to MPEP SourcePatent Application ContentAdding New Claims
Topic

Alternative Limitations (MPEP 2173.05(h))

2 rules
StatutoryRequiredAlways
[mpep-2163-03-72b11986fd7b4b9f5a4455af]
Claim Limitation Requires Corresponding Structure Described in Specification
Note:
A claim using means-plus-function language must be supported by the specification and its equivalents, or it will be considered indefinite.

A claim limitation expressed in means- (or step-) plus-function language “shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.” 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph. If the specification fails to disclose sufficient corresponding structure, materials, or acts that perform the entire claimed function, then the claim limitation is indefinite because the applicant has in effect failed to particularly point out and distinctly claim the invention as required by 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. In re Donaldson Co., 16 F.3d 1189, 1195, 29 USPQ2d 1845, 1850 (Fed. Cir. 1994) (en banc). Such a limitation also lacks an adequate written description as required by 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, because an indefinite, unbounded functional limitation would cover all ways of performing a function and indicate that the inventor has not provided sufficient disclosure to show possession of the invention. See also MPEP § 2181.

Jump to MPEP SourceAlternative Limitations (MPEP 2173.05(h))Lack of Antecedent Basis (MPEP 2173.05(e))Interpreting Claims (MPEP 2173.01)
StatutoryInformativeAlways
[mpep-2163-03-d9a5fa5d6b98340058981bd2]
Means-Plus-Function Claim Limitations Must Be Supported by Corresponding Structure
Note:
Claim limitations expressed in means-plus-function language must be supported by corresponding structure, material, or acts described in the specification to avoid indefiniteness and lack of written description.

A claim limitation expressed in means- (or step-) plus-function language “shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.” 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph. If the specification fails to disclose sufficient corresponding structure, materials, or acts that perform the entire claimed function, then the claim limitation is indefinite because the applicant has in effect failed to particularly point out and distinctly claim the invention as required by 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. In re Donaldson Co., 16 F.3d 1189, 1195, 29 USPQ2d 1845, 1850 (Fed. Cir. 1994) (en banc). Such a limitation also lacks an adequate written description as required by 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, because an indefinite, unbounded functional limitation would cover all ways of performing a function and indicate that the inventor has not provided sufficient disclosure to show possession of the invention. See also MPEP § 2181.

Jump to MPEP SourceAlternative Limitations (MPEP 2173.05(h))35 U.S.C. 112(f) – Means-Plus-Function (MPEP 2181-2186)AIA vs Pre-AIA Practice
Topic

Foreign Priority Claims

1 rules
StatutoryRequiredAlways
[mpep-2163-03-585514a69e103e277c276501]
Claims Entitled to Foreign Priority Date
Note:
Claims in a U.S. application are entitled to the benefit of a foreign priority date if supported by the corresponding foreign application as required by 35 U.S.C. 112.

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(a) or pre-AIA 35 U.S.C. 112, first paragraph. Purdue Pharma LP v. Iancu, 767 Fed. Appx. 918, 923-24, 2019 USPQ2d 136363 (Fed. Cir. 2019); 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).

Jump to MPEP SourceForeign Priority ClaimsProvisional Application Benefit35 U.S.C. 112(a) – Written Description & Enablement
Topic

Optional Claim Content

1 rules
StatutoryPermittedAlways
[mpep-2163-03-2b2ffc2e8970fb238ab2b781]
Claim Must Describe How Function Is Performed
Note:
An original claim lacks written description support if it specifies a function without detailing how the function is achieved, or if it claims a broad genus but only describes narrow species.

While there is a 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), a question as to whether a specification provides an adequate written description may arise in the context of an original claim. An original claim may lack written description support when (1) the claim defines the invention in functional language specifying a desired result but the disclosure fails to sufficiently identify how the function is performed or the result is achieved or (2) a broad genus claim is presented but the disclosure only describes a narrow species with no evidence that the genus is contemplated. See Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1349-50 (Fed. Cir. 2010) (en banc). The written description requirement is not necessarily met when the claim language appears in ipsis verbis in the specification. “Even if a claim is supported by the specification, the language of the specification, to the extent possible, must describe the claimed invention so that one skilled in the art can recognize what is claimed. The appearance of mere indistinct words in a specification or a claim, even an original claim, does not necessarily satisfy that requirement.” Enzo Biochem, Inc. v. Gen-Probe, Inc., 323 F.3d 956, 968, 63 USPQ2d 1609, 1616 (Fed. Cir. 2002).

Jump to MPEP SourceOptional Claim ContentGenus and Species ClaimsOriginal Claims and New Matter
Topic

Missing Information – Enablement (MPEP 2164.06(a))

1 rules
StatutoryRequiredAlways
[mpep-2163-03-22791cbfbb137a763ff20d99]
Claim Limitation Requires Corresponding Structure
Note:
A claim using means-plus-function language must be supported by corresponding structure in the specification to avoid indefiniteness and lack of written description.

A claim limitation expressed in means- (or step-) plus-function language “shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.” 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph. If the specification fails to disclose sufficient corresponding structure, materials, or acts that perform the entire claimed function, then the claim limitation is indefinite because the applicant has in effect failed to particularly point out and distinctly claim the invention as required by 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. In re Donaldson Co., 16 F.3d 1189, 1195, 29 USPQ2d 1845, 1850 (Fed. Cir. 1994) (en banc). Such a limitation also lacks an adequate written description as required by 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, because an indefinite, unbounded functional limitation would cover all ways of performing a function and indicate that the inventor has not provided sufficient disclosure to show possession of the invention. See also MPEP § 2181.

Jump to MPEP SourceMissing Information – Enablement (MPEP 2164.06(a))Alternative Limitations (MPEP 2173.05(h))Lack of Antecedent Basis (MPEP 2173.05(e))
Topic

Possession of the Invention (MPEP 2163.02)

1 rules
StatutoryRequiredAlways
[mpep-2163-03-59294526d8ed485eb7862ac9]
Insufficient Corresponding Structure for Function Claimed
Note:
A claim using means-plus-function language must have adequate corresponding structure in the specification to avoid being indefinite and failing the written description requirement.

A claim limitation expressed in means- (or step-) plus-function language “shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.” 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph. If the specification fails to disclose sufficient corresponding structure, materials, or acts that perform the entire claimed function, then the claim limitation is indefinite because the applicant has in effect failed to particularly point out and distinctly claim the invention as required by 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. In re Donaldson Co., 16 F.3d 1189, 1195, 29 USPQ2d 1845, 1850 (Fed. Cir. 1994) (en banc). Such a limitation also lacks an adequate written description as required by 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, because an indefinite, unbounded functional limitation would cover all ways of performing a function and indicate that the inventor has not provided sufficient disclosure to show possession of the invention. See also MPEP § 2181.

Jump to MPEP SourcePossession of the Invention (MPEP 2163.02)Written Description Requirement (MPEP 2163)Alternative Limitations (MPEP 2173.05(h))
Topic

Adding New Claims

1 rules
MPEP GuidanceRequiredAlways
[mpep-2163-03-201dd27a5aa3953ca7c52cb0]
Claims Must Be Supported by Description
Note:
Amendments to claims or additions of new claims must be supported by the description in the application as filed, as per In re Wright.

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.

Jump to MPEP SourceAdding New ClaimsClaim Status IdentifiersClaim Amendment Practice

Citations

Primary topicCitation
Alternative Limitations (MPEP 2173.05(h))
Foreign Priority Claims
Missing Information – Enablement (MPEP 2164.06(a))
PTAB Jurisdiction
Possession of the Invention (MPEP 2163.02)
Written Description Requirement (MPEP 2163)
35 U.S.C. § 112
Alternative Limitations (MPEP 2173.05(h))
Foreign Priority Claims
Missing Information – Enablement (MPEP 2164.06(a))
PTAB Jurisdiction
Possession of the Invention (MPEP 2163.02)
Written Description Requirement (MPEP 2163)
35 U.S.C. § 112(a)
Alternative Limitations (MPEP 2173.05(h))
Missing Information – Enablement (MPEP 2164.06(a))
Possession of the Invention (MPEP 2163.02)
Written Description Requirement (MPEP 2163)
35 U.S.C. § 112(b)
Alternative Limitations (MPEP 2173.05(h))
Missing Information – Enablement (MPEP 2164.06(a))
Possession of the Invention (MPEP 2163.02)
Written Description Requirement (MPEP 2163)
35 U.S.C. § 112(f)
Foreign Priority Claims
Written Description Requirement (MPEP 2163)
35 U.S.C. § 119(a)
PTAB Jurisdiction35 U.S.C. § 120
MPEP § 2163
Alternative Limitations (MPEP 2173.05(h))
Missing Information – Enablement (MPEP 2164.06(a))
Possession of the Invention (MPEP 2163.02)
Written Description Requirement (MPEP 2163)
MPEP § 2181
Claim Form Requirements
Claims
Optional Claim Content
Original Claims and New Matter
Enzo Biochem, Inc. v. Gen-Probe, Inc., 323 F.3d 956, 968, 63 USPQ2d 1609, 1616 (Fed. Cir. 2002)
Written Description Requirement (MPEP 2163)Fields v. Conover, 443 F.2d 1386, 170 USPQ 276 (CCPA 1971)
Written Description Requirement (MPEP 2163)Hyatt v. Boone, 146 F.3d 1348, 1352, 47 USPQ2d 1128, 1130 (Fed. Cir. 1998)
Foreign Priority Claims
Written Description Requirement (MPEP 2163)
In re Gosteli, 872 F.2d 1008, 10 USPQ2d 1614 (Fed. Cir. 1989)
PTAB JurisdictionIn re Scheiber, 587 F.2d 59, 199 USPQ 782 (CCPA 1978)
Claim Form Requirements
Claims
Optional Claim Content
Original Claims and New Matter
In re Wertheim, 541 F.2d 257, 262, 191 USPQ 90, 96 (CCPA 1976)
Adding New Claims
Claims
In re Wright, 866 F.2d 422, 9 USPQ2d 1649 (Fed. Cir. 1989)
Foreign Priority Claims
Written Description Requirement (MPEP 2163)
In re Ziegler, 992 F.2d 1197, 1200, 26 USPQ2d 1600, 1603 (Fed. Cir. 1993)
Foreign Priority Claims
Written Description Requirement (MPEP 2163)
Kawai v. Metlesics, 480 F.2d 880, 178 USPQ 158 (CCPA 1973)
PTAB JurisdictionTronzo v. Biomet, Inc., 156 F.3d 1154, 47 USPQ2d 1829 (Fed. Cir. 1998)

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: 2025-12-31