MPEP § 1893.03(d) — Unity of Invention (Annotated Rules)

§1893.03(d) Unity of Invention

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

This page consolidates and annotates all enforceable requirements under MPEP § 1893.03(d), 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.

Unity of Invention

This section addresses Unity of Invention. Primary authority: 35 U.S.C. 371, 35 U.S.C. 111(a), and 35 U.S.C. 120. Contains: 4 guidance statements, 1 permission, and 6 other statements.

Key Rules

Topic

Amendments in National Stage

6 rules
StatutoryInformativeAlways
[mpep-1893-03-d-45639a264107e70dcba79562]
Double Patenting Rules Apply to National Stage
Note:
The MPEP sections on double patenting rejections, election and reply by applicant, and rejoinder of nonelected inventions apply to national stage applications under 35 U.S.C. 371.

The sections of the MPEP relating to double patenting rejections (MPEP § 804), election and reply by applicant (MPEP § 818), and rejoinder of nonelected inventions (MPEP § 821.04) generally also apply to national stage applications submitted under 35 U.S.C. 371. See MPEP § 823. Review of a lack of unity requirement is provided for under 37 CFR 1.143 and 1.144. See 37 CFR 1.499 and MPEP § 1002.02(c).

Jump to MPEP Source · 37 CFR 1.143Amendments in National StageNational Stage ExaminationPatent Cooperation Treaty
StatutoryInformativeAlways
[mpep-1893-03-d-d9c094c59381f6113f4bf039]
Corresponding Technical Feature Requirement for Inventions
Note:
The rule requires that inventions linked in a single group must share at least one common technical feature that contributes to the claimed invention over prior art.

A group of inventions is considered linked to form a single general inventive concept where there is a technical relationship among the inventions that involves at least one common or corresponding special technical feature. The expression special technical features is defined as meaning those technical features that define the contribution which each claimed invention, considered as a whole, makes over the prior art. For example, a corresponding technical feature is exemplified by a key defined by certain claimed structural characteristics which correspond to the claimed features of a lock to be used with the claimed key. Note also the examples contained in Chapter 10 of the International Search and Preliminary Examination Guidelines which can be obtained from the Patent Examiner’s Toolkit or WIPO’s website (www.wipo.int/pct/en/texts/gdlines.html).

Jump to MPEP Source · 37 CFR 1.499Amendments in National StageUnity of Invention StandardNational Stage Examination
StatutoryInformativeAlways
[mpep-1893-03-d-af43a9398b63d25e9712d758]
Requirement for Heading in National Stage Lack of Unity Actions
Note:
All national stage applications submitted under 35 U.S.C. 371, including species, must begin Lack of Unity actions with a specific heading.

1. Begin all Lack of Unity actions in national stage applications submitted under 35 U.S.C. 371 (including species) with this heading.

35 U.S.C.Amendments in National StageNational Stage ExaminationPatent Cooperation Treaty
StatutoryInformativeAlways
[mpep-1893-03-d-aa5610171b0000b0e15edc89]
Requirement for Restricting National Stage Application
Note:
This rule requires the examiner to make a restriction requirement in national stage applications submitted under 35 U.S.C. 371 when there is no unity of invention.

1. This form paragraph is to be used when making a restriction requirement in a national stage application submitted under 35 U.S.C. 371.

35 U.S.C.Amendments in National StageRequest Content and FormNational Stage Examination
StatutoryInformativeAlways
[mpep-1893-03-d-9ad5c07567d7d575de3e8722]
Requirement for Election of Species in National Stage Applications
Note:
This rule requires the election of species when making a requirement in a national stage application submitted under 35 U.S.C. 371.

1. This form paragraph is to be used when making an election of species requirement in a national stage application submitted under 35 U.S.C. 371.

35 U.S.C.Amendments in National StageRequest Content and FormNational Stage Examination
StatutoryRecommendedAlways
[mpep-1893-03-d-e7fe808503ef017dee41981f]
Requirement for Restriction in National Stage Applications
Note:
This rule requires the restriction of claims and an election of species when entering a PCT application into the national stage under 35 U.S.C. 371.

1. This form paragraph should be used when requiring restriction (including an election of species) in an application that entered the national stage under 35 U.S.C. 371.

35 U.S.C.Amendments in National StageRequest Content and FormNational Stage Examination
Topic

Manufacture (Article of Manufacture)

3 rules
StatutoryRecommendedAlways
[mpep-1893-03-d-c6fba810025259f5e9cd3852]
Nonelected Product and Process Claims Must Be Rejoined
Note:
Any nonelected product claim that requires all the limitations of an allowable product claim, and any nonelected process claim that requires all the limitations of an allowable process claim, should be rejoined.

If an examiner (1) determines that the claims do not meet the unity of invention requirement and (2) requires election of a single invention, when all of the claims drawn to the elected invention are allowable (i.e., meet the requirements of 35 U.S.C. 101, 102, 103 and 112), the nonelected invention(s) should be considered for rejoinder. Any nonelected product claim that requires all the limitations of an allowable product claim, and any nonelected process claim that requires all the limitations of an allowable process claim, should be rejoined. See MPEP § 821.04. Any nonelected processes of making and/or using an allowable product should be considered for rejoinder. The examiner should notify applicants of potential rejoinder of non-elected process claims by placing form paragraph 8.21.04 at the end of any lack of unity determination made between a product and a process of making the product or between a product and a process of using the product.

Jump to MPEP Source · 37 CFR 1.499Manufacture (Article of Manufacture)Process (Method)Statutory Categories of Invention
StatutoryRecommendedAlways
[mpep-1893-03-d-c28ef79f6e5dbdf436b9dcda]
Nonelected Process Claims for Rejoinder
Note:
Examiner should consider nonelected process claims that require all limitations of an allowable product claim for rejoinder.

If an examiner (1) determines that the claims do not meet the unity of invention requirement and (2) requires election of a single invention, when all of the claims drawn to the elected invention are allowable (i.e., meet the requirements of 35 U.S.C. 101, 102, 103 and 112), the nonelected invention(s) should be considered for rejoinder. Any nonelected product claim that requires all the limitations of an allowable product claim, and any nonelected process claim that requires all the limitations of an allowable process claim, should be rejoined. See MPEP § 821.04. Any nonelected processes of making and/or using an allowable product should be considered for rejoinder. The examiner should notify applicants of potential rejoinder of non-elected process claims by placing form paragraph 8.21.04 at the end of any lack of unity determination made between a product and a process of making the product or between a product and a process of using the product.

Jump to MPEP Source · 37 CFR 1.499Manufacture (Article of Manufacture)Process (Method)Statutory Categories of Invention
StatutoryRecommendedAlways
[mpep-1893-03-d-158a2d9d0c89f4788b1e0454]
Examiner Must Notify Applicants of Potential Rejoinder for Non-Elected Process Claims
Note:
The examiner must inform applicants about the possibility of rejoining non-elected process claims that require all limitations of an allowable product or process claim.

If an examiner (1) determines that the claims do not meet the unity of invention requirement and (2) requires election of a single invention, when all of the claims drawn to the elected invention are allowable (i.e., meet the requirements of 35 U.S.C. 101, 102, 103 and 112), the nonelected invention(s) should be considered for rejoinder. Any nonelected product claim that requires all the limitations of an allowable product claim, and any nonelected process claim that requires all the limitations of an allowable process claim, should be rejoined. See MPEP § 821.04. Any nonelected processes of making and/or using an allowable product should be considered for rejoinder. The examiner should notify applicants of potential rejoinder of non-elected process claims by placing form paragraph 8.21.04 at the end of any lack of unity determination made between a product and a process of making the product or between a product and a process of using the product.

Jump to MPEP Source · 37 CFR 1.499Manufacture (Article of Manufacture)Process (Method)Statutory Categories of Invention
Topic

Final Office Action

1 rules
StatutoryRequiredAlways
[mpep-1893-03-d-e61c17f01527e3472e549dc2]
Requirement for Invention Election Before Final Action
Note:
The examiner may require the applicant to elect an invention before final action if a national stage application lacks unity of invention.

If the examiner finds that a national stage application lacks unity of invention under § 1.475, the examiner may in an Office action require the applicant in the response to that action to elect the invention to which the claims shall be restricted. Such requirement may be made before any action on the merits but may be made at any time before the final action at the discretion of the examiner. Review of any such requirement is provided under §§ 1.143 and 1.144.

Jump to MPEP Source · 37 CFR 1.475Final Office ActionTypes of Office ActionsTraversal of Restriction Requirement
Topic

Patent Cooperation Treaty

1 rules
StatutoryInformativeAlways
[mpep-1893-03-d-9c3f1fa0ad61d7fb0053a817]
Amendment to PCT Rule 13 Effective July 1, 1992
Note:
The Patent Cooperation Treaty Rule 13 was amended on July 1, 1992.

PCT Rule 13 was amended effective July 1, 1992. 37 CFR 1.475 was amended effective May 1, 1993 to correspond to PCT Rule 13.

Jump to MPEP Source · 37 CFR 1.475Patent Cooperation TreatyAmendments in National StageUnity of Invention Standard
Topic

Unity of Invention Standard

1 rules
StatutoryPermittedAlways
[mpep-1893-03-d-08efd706be4f185daf17529c]
37 CFR 1.499 Amended to Match PCT Rule 13
Note:
The rule was updated in May 1993 to align with the amended PCT Rule 13, ensuring consistency in the unity of invention standard during the national stage.

PCT Rule 13 was amended effective July 1, 1992. 37 CFR 1.475 was amended effective May 1, 1993 to correspond to PCT Rule 13.

Jump to MPEP Source · 37 CFR 1.475Unity of Invention StandardPCT Unity of InventionPatent Cooperation Treaty
Topic

PCT Claims Format

1 rules
StatutoryInformativeAlways
[mpep-1893-03-d-436d9f5f306019008cdcc0ae]
Unity of Invention Analysis Applies to National Stage Applications
Note:
Examiners must perform unity of invention analysis, not an independent and distinct analysis, on national stage applications submitted under 35 U.S.C. 371.

Examiners are reminded that unity of invention analysis (not an independent and distinct analysis) is applicable in national stage applications submitted under 35 U.S.C. 371. Restriction practice in accordance with 37 CFR 1.141 – 1.146 continues to apply to U.S. national applications filed under 35 U.S.C. 111(a), even if the application filed under 35 U.S.C. 111(a) claims benefit under 35 U.S.C. 120 and 365(c) to an earlier international application designating the United States or to an earlier U.S. national stage application submitted under 35 U.S.C. 371.

Jump to MPEP Source · 37 CFR 1.141PCT Claims FormatNationals and ResidentsReceiving Office (RO/US)
Topic

Article 19 Amendment Scope

1 rules
StatutoryInformativeAlways
[mpep-1893-03-d-7f76ad510f88deb30f297f2c]
Restriction Practice Applies to U.S. National Applications Claiming Benefit
Note:
The rule requires that restriction practice in accordance with 37 CFR 1.141-1.146 continues to apply even if the application claims benefit from an earlier international or national stage application.

Examiners are reminded that unity of invention analysis (not an independent and distinct analysis) is applicable in national stage applications submitted under 35 U.S.C. 371. Restriction practice in accordance with 37 CFR 1.141 – 1.146 continues to apply to U.S. national applications filed under 35 U.S.C. 111(a), even if the application filed under 35 U.S.C. 111(a) claims benefit under 35 U.S.C. 120 and 365(c) to an earlier international application designating the United States or to an earlier U.S. national stage application submitted under 35 U.S.C. 371.

Jump to MPEP Source · 37 CFR 1.141Article 19 Amendment ScopeNationals and ResidentsReceiving Office (RO/US)
Topic

Lack of Unity Finding

1 rules
StatutoryInformativeAlways
[mpep-1893-03-d-94a9c62030406bba636db7bc]
Review for Lack of Unity Requirement During National Stage
Note:
Provides a review process for the lack of unity requirement in national stage applications under 37 CFR 1.143 and 1.144.

The sections of the MPEP relating to double patenting rejections (MPEP § 804), election and reply by applicant (MPEP § 818), and rejoinder of nonelected inventions (MPEP § 821.04) generally also apply to national stage applications submitted under 35 U.S.C. 371. See MPEP § 823. Review of a lack of unity requirement is provided for under 37 CFR 1.143 and 1.144. See 37 CFR 1.499 and MPEP § 1002.02(c).

Jump to MPEP Source · 37 CFR 1.143Lack of Unity FindingUnity of Invention StandardPCT Unity of Invention
Topic

Request Content and Form

1 rules
StatutoryInformativeAlways
[mpep-1893-03-d-6de3cefcbd8f198d41f96168]
Common Technical Feature Requirement for Linked Inventions
Note:
A group of inventions is considered linked if they share at least one common technical feature that contributes to the invention over prior art.

A group of inventions is considered linked to form a single general inventive concept where there is a technical relationship among the inventions that involves at least one common or corresponding special technical feature. The expression special technical features is defined as meaning those technical features that define the contribution which each claimed invention, considered as a whole, makes over the prior art. For example, a corresponding technical feature is exemplified by a key defined by certain claimed structural characteristics which correspond to the claimed features of a lock to be used with the claimed key. Note also the examples contained in Chapter 10 of the International Search and Preliminary Examination Guidelines which can be obtained from the Patent Examiner’s Toolkit or WIPO’s website (www.wipo.int/pct/en/texts/gdlines.html).

Jump to MPEP Source · 37 CFR 1.499Request Content and FormUnity of Invention StandardPCT Request Form
Topic

International Search Report

1 rules
StatutoryInformativeAlways
[mpep-1893-03-d-50dcff140f2c3c87d0ce22af]
Definition of Special Technical Features for Inventions
Note:
This rule defines special technical features as those that contribute to an invention over the prior art, linking inventions with a common or corresponding feature.

A group of inventions is considered linked to form a single general inventive concept where there is a technical relationship among the inventions that involves at least one common or corresponding special technical feature. The expression special technical features is defined as meaning those technical features that define the contribution which each claimed invention, considered as a whole, makes over the prior art. For example, a corresponding technical feature is exemplified by a key defined by certain claimed structural characteristics which correspond to the claimed features of a lock to be used with the claimed key. Note also the examples contained in Chapter 10 of the International Search and Preliminary Examination Guidelines which can be obtained from the Patent Examiner’s Toolkit or WIPO’s website (www.wipo.int/pct/en/texts/gdlines.html).

Jump to MPEP Source · 37 CFR 1.499International Search ReportSearch in National StageAmendments in National Stage
Topic

Article 34 Amendments

1 rules
StatutoryPermittedAlways
[mpep-1893-03-d-a84b426a8e9557b3027fa53b]
Inventions Linked by Common Technical Feature
Note:
Inventions are considered linked if they share a common technical feature that contributes to the claimed invention over prior art.

A group of inventions is considered linked to form a single general inventive concept where there is a technical relationship among the inventions that involves at least one common or corresponding special technical feature. The expression special technical features is defined as meaning those technical features that define the contribution which each claimed invention, considered as a whole, makes over the prior art. For example, a corresponding technical feature is exemplified by a key defined by certain claimed structural characteristics which correspond to the claimed features of a lock to be used with the claimed key. Note also the examples contained in Chapter 10 of the International Search and Preliminary Examination Guidelines which can be obtained from the Patent Examiner’s Toolkit or WIPO’s website (www.wipo.int/pct/en/texts/gdlines.html).

Jump to MPEP Source · 37 CFR 1.499Article 34 AmendmentsInternational Searching Authority (ISA)Interviews in National Stage
Topic

35 U.S.C. 101 – Patent Eligibility

1 rules
StatutoryRecommendedAlways
[mpep-1893-03-d-0dbfd5d4d1f7099eeec5fbe1]
Nonelected Inventions May Be Rejoined If Allowable
Note:
If all claims of the elected invention are allowable, nonelected inventions can be rejoined into the application.

If an examiner (1) determines that the claims do not meet the unity of invention requirement and (2) requires election of a single invention, when all of the claims drawn to the elected invention are allowable (i.e., meet the requirements of 35 U.S.C. 101, 102, 103 and 112), the nonelected invention(s) should be considered for rejoinder. Any nonelected product claim that requires all the limitations of an allowable product claim, and any nonelected process claim that requires all the limitations of an allowable process claim, should be rejoined. See MPEP § 821.04. Any nonelected processes of making and/or using an allowable product should be considered for rejoinder. The examiner should notify applicants of potential rejoinder of non-elected process claims by placing form paragraph 8.21.04 at the end of any lack of unity determination made between a product and a process of making the product or between a product and a process of using the product.

Jump to MPEP Source · 37 CFR 1.499Patent EligibilityManufacture (Article of Manufacture)Process (Method)
Topic

Withdrawn Claims

1 rules
MPEP GuidanceRecommendedAlways
[mpep-1893-03-d-bacee8f5346f92772ba19a49]
Reconsider Non-Elected Claims After Allowance
Note:
When all claims of the elected invention are allowed, review whether non-elected claims share technical features with the allowable claims.

4. When all of the claims directed to the elected invention are in condition for allowance, the propriety of the restriction requirement should be reconsidered to verify that the non-elected claims do not share a same or corresponding technical feature with the allowable claims.

MPEP § 1893.03(d)Withdrawn ClaimsElection Requirement (MPEP 808, 818)Restriction and Election Practice (MPEP Chapter 800)

Examiner Form Paragraphs

Examiner form paragraphs are standard language that you might see in an Office Action or communication from the USPTO. Examiners have latitude to change the form paragraphs, but you will often see this exact language.

¶ 18.18 ¶ 18.18 Heading for Lack of Unity Action in National Stage Applications Submitted Under 35 U.S.C. 371 (Including Species)

As provided in 37 CFR 1.475( a), a national stage application shall relate to one invention only or to a group of inventions so linked as to form a single general inventive concept (“requirement of unity of invention”). Where a group of inventions is claimed in a national stage application, the requirement of unity of invention shall be fulfilled only when there is a technical relationship among those inventions involving one or more of the same or corresponding special technical features. The expression “special technical features” shall mean those technical features that define a contribution which each of the claimed inventions, considered as a whole, makes over the prior art.

The determination whether a group of inventions is so linked as to form a single general inventive concept shall be made without regard to whether the inventions are claimed in separate claims or as alternatives within a single claim. See 37 CFR 1.475(e) .

As provided in 37 CFR 1.475(b) , a national stage application containing claims to different categories of invention will be considered to have unity of invention if the claims are drawn only to one of the following combinations of categories:

Otherwise, unity of invention might not be present. See 37 CFR 1.475(c) .

¶ 18.19 ¶ 18.19 Restriction Requirement in National Stage Applications Submitted Under 35 U.S.C. 371

Restriction is required under 35 U.S.C. 121 and 372 .

This application contains the following inventions or groups of inventions which are not so linked as to form a single general inventive concept under PCT Rule 13.1 .

In accordance with 37 CFR 1.499 , applicant is required, in reply to this action, to elect a single invention to which the claims must be restricted.

¶ 18.20 ¶ 18.20 Election of Species in National Stage Applications Submitted Under 35 U.S.C. 371

This application contains claims directed to more than one species of the generic invention. These species are deemed to lack unity of invention because they are not so linked as to form a single general inventive concept under PCT Rule 13.1 .

The species are as follows:

[1]

Applicant is required, in reply to this action, to elect a single species to which the claims shall be restricted if no generic claim is finally held to be allowable. The reply must also identify the claims readable on the elected species, including any claims subsequently added. An argument that a claim is allowable or that all claims are generic is considered non-responsive unless accompanied by an election.

Upon the allowance of a generic claim, applicant will be entitled to consideration of claims to additional species which are written in dependent form or otherwise require all the limitations of an allowed generic claim. Currently, the following claim(s) are generic: [2] .

¶ 18.21 ¶ 18.21 Election by Original Presentation in National Stage Applications Submitted Under 35 U.S.C. 371

Newly submitted claim [1] directed to an invention that lacks unity with the invention originally claimed for the following reasons: [2]

Since applicant has received an action on the merits for the originally presented invention, this invention has been constructively elected by original presentation for prosecution on the merits. Accordingly, claim [3] withdrawn from consideration as being directed to a nonelected invention. See 37 CFR 1.142(b) and MPEP § 821.03 .

To preserve a right to petition, the reply to this action must distinctly and specifically point out supposed errors in the restriction requirement. Otherwise, the election shall be treated as a final election without traverse. Traversal must be timely. Failure to timely traverse the requirement will result in the loss of right to petition under 37 CFR 1.144 . If claims are subsequently added, applicant must indicate which of the subsequently added claims are readable upon the elected invention.

Should applicant traverse on the ground that the inventions are not patentably distinct, applicant should submit evidence or identify such evidence now of record showing the inventions to be obvious variants or clearly admit on the record that this is the case. In either instance, if the examiner finds one of the inventions unpatentable over the prior art, the evidence or admission may be used in a rejection under 35 U.S.C. 103 or pre-AIA 35 U.S.C. 103(a) of the other invention.

¶ 18.22 ¶ 18.22 Requirement for Election and Means for Traversal in National Stage Applications Submitted Under 35 U.S.C. 371

Applicant is advised that the reply to this requirement to be complete must include (i) an election of a species or invention to be examined even though the requirement may be traversed ( 37 CFR 1.143 ) and (ii) identification of the claims encompassing the elected invention.

The election of an invention or species may be made with or without traverse. To preserve a right to petition, the election must be made with traverse. If the reply does not distinctly and specifically point out supposed errors in the restriction requirement, the election shall be treated as an election without traverse. Traversal must be presented at the time of election in order to be considered timely. Failure to timely traverse the requirement will result in the loss of right to petition under 37 CFR 1.144. If claims are added after the election, applicant must indicate which of these claims are readable on the elected invention or species.

Should applicant traverse on the ground that the inventions have unity of invention ( 37 CFR 1.475(a) ), applicant must provide reasons in support thereof. Applicant may submit evidence or identify such evidence now of record showing the inventions to be obvious variants or clearly admit on the record that this is the case. Where such evidence or admission is provided by applicant, if the examiner finds one of the inventions unpatentable over the prior art, the evidence or admission may be used in a rejection under 35 U.S.C. 103 or pre-AIA 35 U.S.C. 103(a) of the other invention.

Citations

Primary topicCitation
35 U.S.C. 101 – Patent Eligibility
Manufacture (Article of Manufacture)
35 U.S.C. § 101
Article 19 Amendment Scope
PCT Claims Format
35 U.S.C. § 111(a)
Article 19 Amendment Scope
PCT Claims Format
35 U.S.C. § 120
Amendments in National Stage
Article 19 Amendment Scope
Lack of Unity Finding
PCT Claims Format
35 U.S.C. § 371
Article 19 Amendment Scope
PCT Claims Format
37 CFR § 1.141
Amendments in National Stage
Final Office Action
Lack of Unity Finding
37 CFR § 1.143
Final Office Action
Patent Cooperation Treaty
Unity of Invention Standard
37 CFR § 1.475
Amendments in National Stage
Lack of Unity Finding
37 CFR § 1.499
Amendments in National Stage
Lack of Unity Finding
MPEP § 1002.02(c)
MPEP § 1850
Amendments in National Stage
Lack of Unity Finding
MPEP § 804
Amendments in National Stage
Lack of Unity Finding
MPEP § 818
35 U.S.C. 101 – Patent Eligibility
Amendments in National Stage
Lack of Unity Finding
Manufacture (Article of Manufacture)
MPEP § 821.04
Amendments in National Stage
Lack of Unity Finding
MPEP § 823
Form Paragraph § 18.05
Form Paragraph § 18.19
35 U.S.C. 101 – Patent Eligibility
Manufacture (Article of Manufacture)
Form Paragraph § 8.21.04
Form Paragraph § 8.23.01
Patent Cooperation Treaty
Unity of Invention Standard
PCT Rule 13

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