MPEP § 2185 — Related Issues Under 35 U.S.C. 112(a) or (b) and Pre-AIA 35 U.S.C. 112, First or Second Paragraphs (Annotated Rules)

§2185 Related Issues Under 35 U.S.C. 112(a) or (b) and Pre-AIA 35 U.S.C. 112, First or Second Paragraphs

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

This page consolidates and annotates all enforceable requirements under MPEP § 2185, 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.

Related Issues Under 35 U.S.C. 112(a) or (b) and Pre-AIA 35 U.S.C. 112, First or Second Paragraphs

This section addresses Related Issues Under 35 U.S.C. 112(a) or (b) and Pre-AIA 35 U.S.C. 112, First or Second Paragraphs. Primary authority: 35 U.S.C. 112(b), 35 U.S.C. 112, and 35 U.S.C. 112(f). Contains: 2 requirements, 2 guidance statements, 1 permission, and 2 other statements.

Key Rules

Topic

When 112(f) Is Invoked (MPEP 2181)

2 rules
StatutoryPermittedAlways
[mpep-2185-ec4f45144182a390fb193fd5]
Claim Interpretation May Uncertainly Describe Invention
Note:
The interpretation of claims as per MPEP § 2181 may lead to uncertainty about what the inventor considers the invention, requiring clarification through a rejection under 35 U.S.C. 112.

Interpretation of claims as set forth in MPEP § 2181 may create some uncertainty as to what the inventor or a joint inventor regards as the invention. If this issue arises, it should be addressed in a rejection under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. While 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, permits a particular form of claim limitation, it cannot be read as creating an exception either to the description, enablement or best mode requirements of 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph or the definiteness requirement of 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. In re Knowlton, 481 F.2d 1357, 178 USPQ 486 (CCPA 1973).

Jump to MPEP SourceWhen 112(f) Is Invoked (MPEP 2181)35 U.S.C. 112(f) – Means-Plus-Function (MPEP 2181-2186)Equivalents Under 112(f) (MPEP 2185)
StatutoryInformativeAlways
[mpep-2185-6dbee4e08ef362bf63674301]
Claim Must Be Supported by Specification
Note:
A claim using means-plus-function must be supported by corresponding structure, material, or acts in the specification to avoid rejection under 35 U.S.C. 112.

If a means- (or step-) plus-function limitation recited in a claim is not supported by corresponding structure, material or acts in the specification disclosure, the following rejections under 35 U.S.C. 112 should be considered:

See Noah Systems v. Intuit, 675 F.3d 1302, 1311-19, 102 USPQ2d 1410, 1415-21 (Fed. Cir. 2012); In re Aoyama, 656 F.3d 1293, 1297-98, 99 U.S.P.Q.2d 1936, 1940 (Fed. Cir. 2011); Finisar Corp. v. DirecTV Group, Inc., 523 F.3d 1323, 1340-41, 86 USPQ2d 1609, 1622-23 (Fed. Cir. 2008); and MPEP § 2181.

Jump to MPEP SourceWhen 112(f) Is Invoked (MPEP 2181)35 U.S.C. 112(f) – Means-Plus-Function (MPEP 2181-2186)Equivalents Under 112(f) (MPEP 2185)
Topic

Alternative Limitations (MPEP 2173.05(h))

2 rules
StatutoryRecommendedAlways
[mpep-2185-9bd97ece83483c933b967a21]
Claim Must Be Supported by Specification
Note:
If a means-plus-function limitation in a claim is not supported by corresponding structure, material, or acts in the specification, the claim may be rejected under 35 U.S.C. 112 for lack of enablement, written description, or indefiniteness.
If a means- (or step-) plus-function limitation recited in a claim is not supported by corresponding structure, material or acts in the specification disclosure, the following rejections under 35 U.S.C. 112 should be considered:
  • (A) under 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, as not being supported by an enabling disclosure because the person skilled in the art would not know how to make and use the invention without a description of elements to perform the function. Note that the description of an apparatus with block diagrams describing the function, but not the structure, of the apparatus is not fatal under the enablement requirement of 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, as long as the structure is conventional and can be determined without an undue amount of experimentation. In re Ghiron, 442 F.2d 985, 991, 169 USPQ 723, 727 (CCPA 1971);
  • (B) under 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph as lacking adequate written description because the specification does not 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. As an example, if the means- (or step-) plus-function limitation is computer-implemented, and the specification does not provide a disclosure of the computer and algorithm in sufficient detail to demonstrate to one of ordinary skill in the art that the inventor possessed the invention, see MPEP § 2161.01 and MPEP § 2181, subsection IV, a rejection under 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, for lack of written description must be made; and
  • (C) under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph, as being indefinite. See Noah Systems v. Intuit, 675 F.3d 1302, 1311-19, 102 USPQ2d 1410, 1415-21 (Fed. Cir. 2012); In re Aoyama, 656 F.3d 1293, 1297-98, 99 U.S.P.Q.2d 1936, 1940 (Fed. Cir. 2011); Finisar Corp. v. DirecTV Group, Inc., 523 F.3d 1323, 1340-41, 86 USPQ2d 1609, 1622-23 (Fed. Cir. 2008); and MPEP § 2181.
Jump to MPEP SourceAlternative Limitations (MPEP 2173.05(h))Lack of Antecedent Basis (MPEP 2173.05(e))Corresponding Structure (MPEP 2182)
StatutoryInformativeAlways
[mpep-2185-ecc2a3db99c476a65e3e0834]
Means-Plus-Function Limitation Must Be Supported by Specification
Note:
If a claim uses means-plus-function language, it must be supported by corresponding structure in the specification to avoid rejection under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph.

If a means- (or step-) plus-function limitation recited in a claim is not supported by corresponding structure, material or acts in the specification disclosure, the following rejections under 35 U.S.C. 112 should be considered:

(C) under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph, as being indefinite.

Jump to MPEP SourceAlternative Limitations (MPEP 2173.05(h))35 U.S.C. 112(b) – Definiteness (MPEP 2171-2173)Disclosure Requirements
Topic

Equivalents Under 112(f) (MPEP 2185)

2 rules
StatutoryRequiredAlways
[mpep-2185-97ace4ce5ba8c73814418ecb]
Examiner Must Consider Compliance with Section 101, 102, and 103
Note:
The examiner must evaluate an application against the requirements of 35 U.S.C. 101, 102, and 103 to determine if the claims meet these statutory criteria.

The examiner must also consider an application for compliance with the requirements of 35 U.S.C. 101, 35 U.S.C. 102, and 35 U.S.C. 103. When examining the claims under 35 U.S.C. 102 or 103 a determination of whether the prior art anticipates or renders obvious the claimed subject matter, including the means or step that performs the function specified in the claim, must be made. In the situation when there is no corresponding structure, etc., in the specification to limit the means- (or step-) plus- function limitation, an equivalent is any element that performs the specified function.

Jump to MPEP SourceEquivalents Under 112(f) (MPEP 2185)35 U.S.C. 112(f) – Means-Plus-Function (MPEP 2181-2186)Disclosure Requirements
StatutoryRequiredAlways
[mpep-2185-77fa7f9ddb0a29cc8dd71eec]
Claimed Subject Matter Must Be Anticipated Or Rendered Obvious
Note:
When examining claims under 35 U.S.C. 102 or 103, determine if prior art anticipates or renders the claimed subject matter obvious, including elements performing specified functions.

The examiner must also consider an application for compliance with the requirements of 35 U.S.C. 101, 35 U.S.C. 102, and 35 U.S.C. 103. When examining the claims under 35 U.S.C. 102 or 103 a determination of whether the prior art anticipates or renders obvious the claimed subject matter, including the means or step that performs the function specified in the claim, must be made. In the situation when there is no corresponding structure, etc., in the specification to limit the means- (or step-) plus- function limitation, an equivalent is any element that performs the specified function.

Jump to MPEP SourceEquivalents Under 112(f) (MPEP 2185)35 U.S.C. 112(f) – Means-Plus-Function (MPEP 2181-2186)Disclosure Requirements
Topic

AIA vs Pre-AIA Practice

1 rules
StatutoryRecommendedAlways
[mpep-2185-3e174dd79c67b7cd5eadeeec]
Written Description Must Support Claims
Note:
The written description must support the claims, addressing any uncertainty in claim interpretation.

Interpretation of claims as set forth in MPEP § 2181 may create some uncertainty as to what the inventor or a joint inventor regards as the invention. If this issue arises, it should be addressed in a rejection under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. While 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, permits a particular form of claim limitation, it cannot be read as creating an exception either to the description, enablement or best mode requirements of 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph or the definiteness requirement of 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. In re Knowlton, 481 F.2d 1357, 178 USPQ 486 (CCPA 1973).

Jump to MPEP SourceAIA vs Pre-AIA PracticeDisclosure RequirementsEquivalents Under 112(f) (MPEP 2185)
Topic

Best Mode Under AIA

1 rules
StatutoryProhibitedAlways
[mpep-2185-9e1d8c9cfa7f86019be6c312]
Claim Limitation Does Not Waive Description Requirements
Note:
The claim limitation under 35 U.S.C. 112(f) does not exempt the inventor from meeting the description, enablement, best mode, and definiteness requirements of the patent application.

Interpretation of claims as set forth in MPEP § 2181 may create some uncertainty as to what the inventor or a joint inventor regards as the invention. If this issue arises, it should be addressed in a rejection under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. While 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, permits a particular form of claim limitation, it cannot be read as creating an exception either to the description, enablement or best mode requirements of 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph or the definiteness requirement of 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. In re Knowlton, 481 F.2d 1357, 178 USPQ 486 (CCPA 1973).
While 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, permits a particular form of claim limitation , it cannot be read as creating an exception either to the description, enablement or best mode requirements of 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph or the definiteness requirement of 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. In re Knowlton, 481 F.2d 1357, 178 USPQ 486 (CCPA 1973).

Jump to MPEP SourceBest Mode Under AIA35 U.S.C. 112(f) – Means-Plus-Function (MPEP 2181-2186)AIA vs Pre-AIA Practice
Topic

Corresponding Structure (MPEP 2182)

1 rules
StatutoryInformativeAlways
[mpep-2185-df530deaccb5c5bc81d3d51f]
Equivalent Element for Means-Plus-Function Claim
Note:
An element that performs the specified function in a claim is considered an equivalent if no corresponding structure is described in the specification.

The examiner must also consider an application for compliance with the requirements of 35 U.S.C. 101, 35 U.S.C. 102, and 35 U.S.C. 103. When examining the claims under 35 U.S.C. 102 or 103 a determination of whether the prior art anticipates or renders obvious the claimed subject matter, including the means or step that performs the function specified in the claim, must be made. In the situation when there is no corresponding structure, etc., in the specification to limit the means- (or step-) plus- function limitation, an equivalent is any element that performs the specified function.

Jump to MPEP SourceCorresponding Structure (MPEP 2182)Equivalents Under 112(f) (MPEP 2185)112(f) Indefiniteness (MPEP 2186)

Citations

Primary topicCitation
Corresponding Structure (MPEP 2182)
Equivalents Under 112(f) (MPEP 2185)
35 U.S.C. § 101
Corresponding Structure (MPEP 2182)
Equivalents Under 112(f) (MPEP 2185)
35 U.S.C. § 102
Corresponding Structure (MPEP 2182)
Equivalents Under 112(f) (MPEP 2185)
35 U.S.C. § 103
AIA vs Pre-AIA Practice
Alternative Limitations (MPEP 2173.05(h))
Best Mode Under AIA
When 112(f) Is Invoked (MPEP 2181)
35 U.S.C. § 112
AIA vs Pre-AIA Practice
Alternative Limitations (MPEP 2173.05(h))
Best Mode Under AIA
When 112(f) Is Invoked (MPEP 2181)
35 U.S.C. § 112(a)
AIA vs Pre-AIA Practice
Alternative Limitations (MPEP 2173.05(h))
Best Mode Under AIA
When 112(f) Is Invoked (MPEP 2181)
35 U.S.C. § 112(b)
AIA vs Pre-AIA Practice
Best Mode Under AIA
When 112(f) Is Invoked (MPEP 2181)
35 U.S.C. § 112(f)
Alternative Limitations (MPEP 2173.05(h))MPEP § 2161.01
AIA vs Pre-AIA Practice
Alternative Limitations (MPEP 2173.05(h))
Best Mode Under AIA
When 112(f) Is Invoked (MPEP 2181)
MPEP § 2181
Alternative Limitations (MPEP 2173.05(h))In re Ghiron, 442 F.2d 985, 991, 169 USPQ 723, 727 (CCPA 1971)
AIA vs Pre-AIA Practice
Best Mode Under AIA
When 112(f) Is Invoked (MPEP 2181)
In re Knowlton, 481 F.2d 1357, 178 USPQ 486 (CCPA 1973)

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