MPEP § 2165.01 — Considerations Relevant to Best Mode (Annotated Rules)

§2165.01 Considerations Relevant to Best Mode

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

This page consolidates and annotates all enforceable requirements under MPEP § 2165.01, 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.

Considerations Relevant to Best Mode

This section addresses Considerations Relevant to Best Mode. Primary authority: 35 U.S.C. 119, 35 U.S.C. 119(e), and 35 U.S.C. 112(a). Contains: 2 requirements, 1 prohibition, and 2 guidance statements.

Key Rules

Topic

Patent Application Content

2 rules
StatutoryProhibitedAlways
[mpep-2165-01-9343a74004fdca933da79530]
Best Mode Must Be Disclosed at Filing
Note:
The patent application must disclose the best mode contemplated by the inventor at the time of filing; amendments cannot add this requirement after submission.

If the best mode contemplated by the inventor at the time of filing the application is not disclosed, such a defect cannot be cured by submitting an amendment seeking to put into the specification something required to be there when the patent application was originally filed. In re Hay, 534 F.2d 917, 189 USPQ 790 (CCPA 1976).

Jump to MPEP SourcePatent Application Content
MPEP GuidanceRequiredAlways
[mpep-2165-01-8da4ab06c29268393ec46e43]
Patent Specification Not Required to Be Production Specification
Note:
A patent specification does not need to include a specific example and is not intended to serve as a production manual.

There is no statutory requirement for the disclosure of a specific example — a patent specification is not intended nor required to be a production specification. In re Gay, 309 F.2d 768, 135 USPQ 311 (CCPA 1962).

Jump to MPEP SourcePatent Application Content
Topic

Means-Plus-Function Claims

2 rules
MPEP GuidanceInformativeAlways
[mpep-2165-01-7eb8dc4b7e7b3daaeb4785bd]
Claims Must Define Invention
Note:
The invention must be defined in the claims, with the specification not required to include details unrelated to its essence.

Determine what the invention is — the invention is defined in the claims. The specification need not set forth details not relating to the essence of the invention. In re Bosy, 360 F.2d 972, 149 USPQ 789 (CCPA 1966). See also Northern Telecom Ltd. v. Samsung Elec. Co., 215 F.3d 1281, 55 USPQ2d 1065 (Fed. Cir. 2000) (Unclaimed matter that is unrelated to the operation of the claimed invention does not trigger the best mode requirement); Eli Lilly & Co. v. Barr Lab. Inc., 251 F.3d 955, 966, 58 USPQ2d 1865, 1877 (Fed. Cir. 2001) (“[P]atentee’s failure to disclose an unclaimed preferred mode for accomplishing a routine detail does not violate the best mode requirement because one skilled in the art is aware of alternative means for accomplishing the routine detail that would still produce the best mode of the claimed invention.”).

Jump to MPEP SourceMeans-Plus-Function ClaimsWhen 112(f) Is Invoked (MPEP 2181)
MPEP GuidanceInformativeAlways
[mpep-2165-01-4527ac9b745dc043304035c6]
Specification Need Not Include Unrelated Details
Note:
The specification does not need to include details that are not essential to the invention's operation.

Determine what the invention is — the invention is defined in the claims. The specification need not set forth details not relating to the essence of the invention. In re Bosy, 360 F.2d 972, 149 USPQ 789 (CCPA 1966). See also Northern Telecom Ltd. v. Samsung Elec. Co., 215 F.3d 1281, 55 USPQ2d 1065 (Fed. Cir. 2000) (Unclaimed matter that is unrelated to the operation of the claimed invention does not trigger the best mode requirement); Eli Lilly & Co. v. Barr Lab. Inc., 251 F.3d 955, 966, 58 USPQ2d 1865, 1877 (Fed. Cir. 2001) (“[P]atentee’s failure to disclose an unclaimed preferred mode for accomplishing a routine detail does not violate the best mode requirement because one skilled in the art is aware of alternative means for accomplishing the routine detail that would still produce the best mode of the claimed invention.”).

Jump to MPEP SourceMeans-Plus-Function ClaimsWhen 112(f) Is Invoked (MPEP 2181)
Topic

Best Mode Requirement (MPEP 2165)

1 rules
StatutoryRequiredAlways
[mpep-2165-01-b163a19d919a38ead17a5f6e]
No Requirement to Update Best Mode for Priority Applications
Note:
The rule states that there is no requirement to update the best mode in applications claiming the benefit of an earlier filing date under 35 U.S.C. 119(e) or 120.

There is no requirement to update in the context of a foreign priority application under 35 U.S.C. 119, Standard Oil Co. v. Montedison, S.p.A., 494 F.Supp. 370, 206 USPQ 676 (D.Del. 1980) (better catalyst developed between Italian priority and U.S. filing dates). Furthermore, it is not necessary to update the best mode in applications claiming the benefit of an earlier filing date under 35 U.S.C. 119(e) or 120, which indicate that the disclosure in the earlier filed application must be made in the manner provided by 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph, "other than the requirement to disclose the best mode." See MPEP § 2165, subsection II.

Jump to MPEP SourceBest Mode Requirement (MPEP 2165)Best Mode Under AIA35 U.S.C. 112(a) – Written Description & Enablement
Topic

Support in Original Patent

1 rules
StatutoryRecommendedAlways
[mpep-2165-01-fa53b302d30e3f2ffb1b8813]
Invention Modes Must Be Described
Note:
Any new mode of practicing the invention not described in the original application should be treated as new matter and objected to.

Any proposed amendment of this type (adding a specific mode of practicing the invention not described in the application as filed) should be treated as new matter. New matter under 35 U.S.C. 132 and 251 should be objected to and coupled with a requirement to cancel the new matter.

Jump to MPEP SourceSupport in Original PatentNo New Matter in ReissueAmendments in Reissue
Topic

No New Matter in Reissue

1 rules
StatutoryRecommendedAlways
[mpep-2165-01-f8471236709d375038c2238e]
Requirement to Cancel New Matter in Reissue
Note:
Any amendment adding a specific mode of practicing the invention not described in the application as filed must be objected to and require cancellation.

Any proposed amendment of this type (adding a specific mode of practicing the invention not described in the application as filed) should be treated as new matter. New matter under 35 U.S.C. 132 and 251 should be objected to and coupled with a requirement to cancel the new matter.

Jump to MPEP SourceNo New Matter in ReissueReissue Patent PracticeSupport in Original Patent

Citations

Primary topicCitation
Best Mode Requirement (MPEP 2165)35 U.S.C. § 112
Best Mode Requirement (MPEP 2165)35 U.S.C. § 112(a)
Best Mode Requirement (MPEP 2165)35 U.S.C. § 119
Best Mode Requirement (MPEP 2165)35 U.S.C. § 119(e)
No New Matter in Reissue
Support in Original Patent
35 U.S.C. § 132
Best Mode Requirement (MPEP 2165)MPEP § 2165
Means-Plus-Function ClaimsIn re Bosy, 360 F.2d 972, 149 USPQ 789 (CCPA 1966)
Patent Application ContentIn re Gay, 309 F.2d 768, 135 USPQ 311 (CCPA 1962)
Patent Application ContentIn re Hay, 534 F.2d 917, 189 USPQ 790 (CCPA 1976)
In re Honn, 364 F.2d 454, 150 USPQ 652 (CCPA 1966)

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