MPEP § 2138.01 — Interference Practice (Annotated Rules)

§2138.01 Interference Practice

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

This page consolidates and annotates all enforceable requirements under MPEP § 2138.01, 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.

Interference Practice

This section addresses Interference Practice. Primary authority: 35 U.S.C. 100, 35 U.S.C. 102, and 35 U.S.C. 102(g). Contains: 1 permission and 13 other statements.

Key Rules

Topic

Interference Proceedings (Pre-AIA)

6 rules
StatutoryInformativeAlways
[mpep-2138-01-29e584c74cfdc93e6cd1c596]
Conception and Reduction to Practice on Effective Filing Date
Note:
For analysis under 37 CFR 1.131, the conception and reduction to practice of a reference are considered to occur on the effective filing date or printed publication date.

For purposes of analysis under 37 CFR 1.131, the conception and reduction to practice of the reference to be antedated are both considered to be on the effective filing date of domestic patent or foreign patent or the date of printed publication.

Jump to MPEP Source · 37 CFR 1.131Interference Proceedings (Pre-AIA)
StatutoryInformativeAlways
[mpep-2138-01-92174c4d845b606fa9acfac8]
Inventor A Conceived Before B
Note:
In an interference, inventor A is awarded priority if they conceived the invention before B and reduced it to practice constructively before B did.

A is awarded priority in an interference, or antedates B as a reference in the context of a declaration or affidavit filed under 37 CFR 1.131, because A conceived the invention before B and constructively reduced the invention to practice before B reduced the invention to practice. The same result would be reached if the conception date was the same for both inventors A and B.

Jump to MPEP Source · 37 CFR 1.131Interference Proceedings (Pre-AIA)
StatutoryInformativeAlways
[mpep-2138-01-42444e990a12a487bf1c96e4]
Same Result If Conception Dates Match
Note:
If both inventors A and B conceived the invention on the same date, A is still awarded priority in an interference or antedates B as a reference.

A is awarded priority in an interference, or antedates B as a reference in the context of a declaration or affidavit filed under 37 CFR 1.131, because A conceived the invention before B and constructively reduced the invention to practice before B reduced the invention to practice. The same result would be reached if the conception date was the same for both inventors A and B.

Jump to MPEP Source · 37 CFR 1.131Interference Proceedings (Pre-AIA)
StatutoryPermittedAlways
[mpep-2138-01-82dd33db1bed1da8914dd8d1]
Invention Must Be Constructively Reduced to Practice Before B’s Conception
Note:
A must show reasonable diligence from a point just before B's conception until Rc, having conceived the invention before B and constructively reduced it to practice even after B did so.

A is awarded priority in an interference, or antedates B as a reference in the context of a declaration or affidavit filed under 37 CFR 1.131, if A can show reasonable diligence from T D (a point just prior to B’s conception) until Rc because A conceived the invention before B, and diligently constructively reduced the invention to practice even though this was after B reduced the invention to practice.

Jump to MPEP Source · 37 CFR 1.131Interference Proceedings (Pre-AIA)
StatutoryInformativeAlways
[mpep-2138-01-f5ff8b6a453bbcf9bf5734d8]
Invention Conceived and Reduced to Practice Before Another
Note:
A declaration or affidavit filed under 37 CFR 1.131 must establish that the invention was conceived by A before B and actually reduced to practice by A before B did so.

A antedates B as a reference in the context of a declaration or affidavit filed under 37 CFR 1.131 because A conceived the invention before B and actually reduced the invention to practice before B reduced the invention to practice.

Jump to MPEP Source · 37 CFR 1.131Interference Proceedings (Pre-AIA)
StatutoryInformativeAlways
[mpep-2138-01-094a1dbba92bf619d524f3ad]
Invention Conceived Before B Despite Later Practice
Note:
A must be considered the antedating reference because A conceived the invention before B, and diligently reduced it to practice even after B did so.

A antedates B as a reference in the context of a declaration or affidavit filed under 37 CFR 1.131 because A conceived the invention before B, and diligently actually reduced the invention to practice, even though this was after B reduced the invention to practice.

Jump to MPEP Source · 37 CFR 1.131Interference Proceedings (Pre-AIA)
Topic

Diligence Requirement

4 rules
StatutoryInformativeAlways
[mpep-2138-01-51215beb62e301c3ec6d5d67]
Diligence Required for Prior Invention
Note:
The rule requires that the first to reduce an invention to practice with diligence is considered the inventor, unless another was the first to conceive and act diligently from a prior time.

Subsection (g) of pre-AIA 35 U.S.C. 102 is the basis of interference practice for determining priority of invention between two parties. See Bigham v. Godtfredsen, 857 F.2d 1415, 1416, 8 USPQ2d 1266, 1267 (Fed. Cir. 1988); Paulik v. Rizkalla, 760 F.2d 1270, 1276-81, 226 USPQ 224, 225 (Fed. Cir. 1985) (reviews the legislative history of the subsection in a concurring opinion by Judge Rich). 35 U.S.C. 135, 37 CFR Part 41, Subparts D and E and MPEP Chapter 2300. An interference is an inter partes proceeding directed at determining the first to invent as among the parties to the proceeding, involving two or more pending applications naming different inventors or one or more pending applications and one or more unexpired patents naming different inventors. The first of many to reduce an invention to practice around the same time will be the sole party to obtain a patent in some instances, Radio Corp. of America v. Radio Eng’g Labs., Inc., 293 U.S. 1, 2, 21 USPQ 353, 353-4 (1934), unless another was the first to conceive and couple a later-in-time reduction to practice with diligence from a time just prior to when the second conceiver entered the field to the first conceiver’s reduction to practice. Hull v. Davenport, 90 F.2d 103, 105, 33 USPQ 506, 508 (CCPA 1937). See the priority time charts below illustrating this point. Upon conclusion of an interference, subject matter claimed by the losing party that was the basis of the interference is rejected under pre-AIA 35 U.S.C. 102(g), unless the acts showing prior invention were not in this country.

Jump to MPEP SourceDiligence RequirementCritical Period for DiligenceConception and Reduction to Practice
StatutoryInformativeAlways
[mpep-2138-01-b5e1c8b976736835a9a8c2e5]
Diligence Required for Prior Invention
Note:
The rule requires that the first to conceive and diligently reduce an invention to practice be entitled to a patent, unless another was the first to invent.

Subsection (g) of pre-AIA 35 U.S.C. 102 is the basis of interference practice for determining priority of invention between two parties. See Bigham v. Godtfredsen, 857 F.2d 1415, 1416, 8 USPQ2d 1266, 1267 (Fed. Cir. 1988); Paulik v. Rizkalla, 760 F.2d 1270, 1276-81, 226 USPQ 224, 225 (Fed. Cir. 1985) (reviews the legislative history of the subsection in a concurring opinion by Judge Rich). 35 U.S.C. 135, 37 CFR Part 41, Subparts D and E and MPEP Chapter 2300. An interference is an inter partes proceeding directed at determining the first to invent as among the parties to the proceeding, involving two or more pending applications naming different inventors or one or more pending applications and one or more unexpired patents naming different inventors. The first of many to reduce an invention to practice around the same time will be the sole party to obtain a patent in some instances, Radio Corp. of America v. Radio Eng’g Labs., Inc., 293 U.S. 1, 2, 21 USPQ 353, 353-4 (1934), unless another was the first to conceive and couple a later-in-time reduction to practice with diligence from a time just prior to when the second conceiver entered the field to the first conceiver’s reduction to practice. Hull v. Davenport, 90 F.2d 103, 105, 33 USPQ 506, 508 (CCPA 1937). See the priority time charts below illustrating this point. Upon conclusion of an interference, subject matter claimed by the losing party that was the basis of the interference is rejected under pre-AIA 35 U.S.C. 102(g), unless the acts showing prior invention were not in this country.

Jump to MPEP SourceDiligence RequirementCritical Period for DiligenceConception and Reduction to Practice
StatutoryInformativeAlways
[mpep-2138-01-e497956c97cbad57bd74154b]
First to Reduce Invention to Practice Gains Priority Unless Diligent Second Conceiver
Note:
The first inventor to reduce an invention to practice gains priority unless a second, diligent conceiver reduces it later.

Subsection (g) of pre-AIA 35 U.S.C. 102 is the basis of interference practice for determining priority of invention between two parties. See Bigham v. Godtfredsen, 857 F.2d 1415, 1416, 8 USPQ2d 1266, 1267 (Fed. Cir. 1988); Paulik v. Rizkalla, 760 F.2d 1270, 1276-81, 226 USPQ 224, 225 (Fed. Cir. 1985) (reviews the legislative history of the subsection in a concurring opinion by Judge Rich). 35 U.S.C. 135, 37 CFR Part 41, Subparts D and E and MPEP Chapter 2300. An interference is an inter partes proceeding directed at determining the first to invent as among the parties to the proceeding, involving two or more pending applications naming different inventors or one or more pending applications and one or more unexpired patents naming different inventors. The first of many to reduce an invention to practice around the same time will be the sole party to obtain a patent in some instances, Radio Corp. of America v. Radio Eng’g Labs., Inc., 293 U.S. 1, 2, 21 USPQ 353, 353-4 (1934), unless another was the first to conceive and couple a later-in-time reduction to practice with diligence from a time just prior to when the second conceiver entered the field to the first conceiver’s reduction to practice. Hull v. Davenport, 90 F.2d 103, 105, 33 USPQ 506, 508 (CCPA 1937). See the priority time charts below illustrating this point. Upon conclusion of an interference, subject matter claimed by the losing party that was the basis of the interference is rejected under pre-AIA 35 U.S.C. 102(g), unless the acts showing prior invention were not in this country.

Jump to MPEP SourceDiligence RequirementCritical Period for DiligenceConception and Reduction to Practice
StatutoryInformativeAlways
[mpep-2138-01-abc119ac5f6199f08fede86e]
Diligence Required for Prior Invention
Note:
The rule requires that the party claiming prior invention must demonstrate diligence in reducing the invention to practice.

Subsection (g) of pre-AIA 35 U.S.C. 102 is the basis of interference practice for determining priority of invention between two parties. See Bigham v. Godtfredsen, 857 F.2d 1415, 1416, 8 USPQ2d 1266, 1267 (Fed. Cir. 1988); Paulik v. Rizkalla, 760 F.2d 1270, 1276-81, 226 USPQ 224, 225 (Fed. Cir. 1985) (reviews the legislative history of the subsection in a concurring opinion by Judge Rich). 35 U.S.C. 135, 37 CFR Part 41, Subparts D and E and MPEP Chapter 2300. An interference is an inter partes proceeding directed at determining the first to invent as among the parties to the proceeding, involving two or more pending applications naming different inventors or one or more pending applications and one or more unexpired patents naming different inventors. The first of many to reduce an invention to practice around the same time will be the sole party to obtain a patent in some instances, Radio Corp. of America v. Radio Eng’g Labs., Inc., 293 U.S. 1, 2, 21 USPQ 353, 353-4 (1934), unless another was the first to conceive and couple a later-in-time reduction to practice with diligence from a time just prior to when the second conceiver entered the field to the first conceiver’s reduction to practice. Hull v. Davenport, 90 F.2d 103, 105, 33 USPQ 506, 508 (CCPA 1937). See the priority time charts below illustrating this point. Upon conclusion of an interference, subject matter claimed by the losing party that was the basis of the interference is rejected under pre-AIA 35 U.S.C. 102(g), unless the acts showing prior invention were not in this country.

Jump to MPEP SourceDiligence RequirementCritical Period for DiligenceConception and Reduction to Practice
Topic

Antedating Reference – Pre-AIA (MPEP 2136.05)

3 rules
StatutoryInformativeAlways
[mpep-2138-01-b6098a933e9dc073cc60383c]
Subject Matter Claimed by Loser Rejected Under Pre-AIA 35 U.S.C. 102(g)
Note:
If a party loses an interference, their claimed subject matter is rejected under pre-AIA 35 U.S.C. 102(g) unless the prior invention acts were not in this country.

Subsection (g) of pre-AIA 35 U.S.C. 102 is the basis of interference practice for determining priority of invention between two parties. See Bigham v. Godtfredsen, 857 F.2d 1415, 1416, 8 USPQ2d 1266, 1267 (Fed. Cir. 1988); Paulik v. Rizkalla, 760 F.2d 1270, 1276-81, 226 USPQ 224, 225 (Fed. Cir. 1985) (reviews the legislative history of the subsection in a concurring opinion by Judge Rich). 35 U.S.C. 135, 37 CFR Part 41, Subparts D and E and MPEP Chapter 2300. An interference is an inter partes proceeding directed at determining the first to invent as among the parties to the proceeding, involving two or more pending applications naming different inventors or one or more pending applications and one or more unexpired patents naming different inventors. The first of many to reduce an invention to practice around the same time will be the sole party to obtain a patent in some instances, Radio Corp. of America v. Radio Eng’g Labs., Inc., 293 U.S. 1, 2, 21 USPQ 353, 353-4 (1934), unless another was the first to conceive and couple a later-in-time reduction to practice with diligence from a time just prior to when the second conceiver entered the field to the first conceiver’s reduction to practice. Hull v. Davenport, 90 F.2d 103, 105, 33 USPQ 506, 508 (CCPA 1937). See the priority time charts below illustrating this point. Upon conclusion of an interference, subject matter claimed by the losing party that was the basis of the interference is rejected under pre-AIA 35 U.S.C. 102(g), unless the acts showing prior invention were not in this country.

Jump to MPEP SourceAntedating Reference – Pre-AIA (MPEP 2136.05)Pre-AIA 102(a) – Known or Used (MPEP 2132)Pre-AIA 102(g) – Prior Invention (MPEP 2138)
StatutoryInformativeAlways
[mpep-2138-01-73561c1dcac48baf768bb5d6]
Time Charts for Antedating Pre-AIA References
Note:
These charts apply to interference proceedings and declarations under 37 CFR 1.131 to antedate references as prior art under pre-AIA 35 U.S.C. 102(a) or 102(e).

The following priority time charts illustrate the award of invention priority in several situations. The time charts apply to interference proceedings and are also applicable to declarations or affidavits filed under 37 CFR 1.131 to antedate references which are available as prior art under pre-AIA 35 U.S.C. 102(a) or 102(e). Note, however, in the context of 37 CFR 1.131, an inventor does not have to show that the invention was not abandoned, suppressed, or concealed from the time of an actual reduction to practice to a constructive reduction to practice because the length of time taken to file a patent application after an actual reduction to practice is generally of no consequence except in an interference proceeding. Paulik v. Rizkalla, 760 F.2d 1270, 226 USPQ 224 (Fed. Cir. 1985). See the discussion of abandonment, suppression, and concealment in MPEP § 2138.03.

Jump to MPEP Source · 37 CFR 1.131Antedating Reference – Pre-AIA (MPEP 2136.05)Pre-AIA 102(g) – Prior Invention (MPEP 2138)Prior Art Under Pre-AIA 35 U.S.C. 102 (MPEP 2131-2138)
StatutoryInformativeAlways
[mpep-2138-01-dc1b8522322982b56f542d3d]
Prior Art Not Open to Further Inquiry During Interference
Note:
Subject matter that is prior art under pre-AIA 35 U.S.C. 102(g) and is subject to an interference cannot be further questioned during the interference proceeding.

Interference practice operates to the exclusion of ex parte practice under 37 CFR 1.131 which permits an inventor to show an actual date of invention prior to the effective date of a reference or activity applied under pre-AIA 35 U.S.C. 102 or 103, as long as the reference is not a statutory bar under pre-AIA 35 U.S.C. 102(b) or a U.S. patent application publication claiming the same patentable invention. Ex parte Standish, 10 USPQ2d 1454, 1457 (Bd. Pat. App. & Inter. 1988) (An application claim to the “same patentable invention” claimed in a domestic patent requires interference rather than an affidavit under 37 CFR 1.131 to antedate the patent. The term “same patentable invention” encompasses a claim that is either anticipated by or obvious in view of the subject matter recited in the patent claim.). Subject matter which is prior art under pre-AIA 35 U.S.C. 102(g) and is subject to an interference is not open to further inquiry under 37 CFR 1.131 during the interference proceeding.

Jump to MPEP Source · 37 CFR 1.131Antedating Reference – Pre-AIA (MPEP 2136.05)Pre-AIA 102(g) – Prior Invention (MPEP 2138)Prior Art Under AIA 35 U.S.C. 102 (MPEP 2150-2159)
Topic

Conception and Reduction to Practice

2 rules
StatutoryInformativeAlways
[mpep-2138-01-196c0988386b594044cd02b5]
First to Invent Determined by Inter Partes Proceeding
Note:
An inter partes proceeding is used to determine which party was the first to invent, involving two or more pending applications with different inventors.

Subsection (g) of pre-AIA 35 U.S.C. 102 is the basis of interference practice for determining priority of invention between two parties. See Bigham v. Godtfredsen, 857 F.2d 1415, 1416, 8 USPQ2d 1266, 1267 (Fed. Cir. 1988); Paulik v. Rizkalla, 760 F.2d 1270, 1276-81, 226 USPQ 224, 225 (Fed. Cir. 1985) (reviews the legislative history of the subsection in a concurring opinion by Judge Rich). 35 U.S.C. 135, 37 CFR Part 41, Subparts D and E and MPEP Chapter 2300. An interference is an inter partes proceeding directed at determining the first to invent as among the parties to the proceeding, involving two or more pending applications naming different inventors or one or more pending applications and one or more unexpired patents naming different inventors. The first of many to reduce an invention to practice around the same time will be the sole party to obtain a patent in some instances, Radio Corp. of America v. Radio Eng’g Labs., Inc., 293 U.S. 1, 2, 21 USPQ 353, 353-4 (1934), unless another was the first to conceive and couple a later-in-time reduction to practice with diligence from a time just prior to when the second conceiver entered the field to the first conceiver’s reduction to practice. Hull v. Davenport, 90 F.2d 103, 105, 33 USPQ 506, 508 (CCPA 1937). See the priority time charts below illustrating this point. Upon conclusion of an interference, subject matter claimed by the losing party that was the basis of the interference is rejected under pre-AIA 35 U.S.C. 102(g), unless the acts showing prior invention were not in this country.

Jump to MPEP SourceConception and Reduction to PracticePre-AIA 102(g) – Prior Invention (MPEP 2138)Priority in Interference
StatutoryInformativeAlways
[mpep-2138-01-79fe6ae73df5387668bbda7b]
Interference Excludes Ex Parte Anticipation
Note:
In an interference proceeding, ex parte practice under 37 CFR 1.131 to show an earlier date of invention is not permitted if the reference is prior art under pre-AIA 35 U.S.C. 102(g).

Interference practice operates to the exclusion of ex parte practice under 37 CFR 1.131 which permits an inventor to show an actual date of invention prior to the effective date of a reference or activity applied under pre-AIA 35 U.S.C. 102 or 103, as long as the reference is not a statutory bar under pre-AIA 35 U.S.C. 102(b) or a U.S. patent application publication claiming the same patentable invention. Ex parte Standish, 10 USPQ2d 1454, 1457 (Bd. Pat. App. & Inter. 1988) (An application claim to the “same patentable invention” claimed in a domestic patent requires interference rather than an affidavit under 37 CFR 1.131 to antedate the patent. The term “same patentable invention” encompasses a claim that is either anticipated by or obvious in view of the subject matter recited in the patent claim.). Subject matter which is prior art under pre-AIA 35 U.S.C. 102(g) and is subject to an interference is not open to further inquiry under 37 CFR 1.131 during the interference proceeding.

Jump to MPEP Source · 37 CFR 1.131Conception and Reduction to PracticeAIA Effective DatesAIA 102(a)(2) – Earlier Filed Applications (MPEP 2154)
Topic

Actual Reduction to Practice

2 rules
StatutoryInformativeAlways
[mpep-2138-01-b3da358c18e82e08570dd41f]
Invention Priority Awarded Based on Time Charts
Note:
The rule describes how invention priority is determined using time charts in interference proceedings and for pre-AIA prior art.

The following priority time charts illustrate the award of invention priority in several situations. The time charts apply to interference proceedings and are also applicable to declarations or affidavits filed under 37 CFR 1.131 to antedate references which are available as prior art under pre-AIA 35 U.S.C. 102(a) or 102(e). Note, however, in the context of 37 CFR 1.131, an inventor does not have to show that the invention was not abandoned, suppressed, or concealed from the time of an actual reduction to practice to a constructive reduction to practice because the length of time taken to file a patent application after an actual reduction to practice is generally of no consequence except in an interference proceeding. Paulik v. Rizkalla, 760 F.2d 1270, 226 USPQ 224 (Fed. Cir. 1985). See the discussion of abandonment, suppression, and concealment in MPEP § 2138.03.

Jump to MPEP Source · 37 CFR 1.131Actual Reduction to PracticeConstructive Reduction (Filing)Conception and Reduction to Practice
StatutoryInformativeAlways
[mpep-2138-01-b4103791a5b3af4aea632358]
Time After Actual Reduction to Practice Is Irrelevant
Note:
An inventor does not need to prove the invention was not abandoned, suppressed, or concealed after actual reduction to practice for filing a patent application, except in interference proceedings.

The following priority time charts illustrate the award of invention priority in several situations. The time charts apply to interference proceedings and are also applicable to declarations or affidavits filed under 37 CFR 1.131 to antedate references which are available as prior art under pre-AIA 35 U.S.C. 102(a) or 102(e). Note, however, in the context of 37 CFR 1.131, an inventor does not have to show that the invention was not abandoned, suppressed, or concealed from the time of an actual reduction to practice to a constructive reduction to practice because the length of time taken to file a patent application after an actual reduction to practice is generally of no consequence except in an interference proceeding. Paulik v. Rizkalla, 760 F.2d 1270, 226 USPQ 224 (Fed. Cir. 1985). See the discussion of abandonment, suppression, and concealment in MPEP § 2138.03.

Jump to MPEP Source · 37 CFR 1.131Actual Reduction to PracticeConstructive Reduction (Filing)Conception and Reduction to Practice
Topic

Key Changes Under AIA

1 rules
StatutoryInformativeAlways
[mpep-2138-01-d592fb40daf0199ce7475c80]
Interference Practice Under AIA
Note:
This rule outlines the specific practices for interference proceedings under the America Invents Act (AIA).

[Editor Note: This MPEP section has limited applicability to applications subject to examination under the first inventor to file (FITF) provisions of the AIA as set forth in 35 U.S.C. 100 (note). Patents and applications that contain (or contained at any time) at least one claim with a pre-AIA effective filing date (before March 16, 2013) and at least one claim with a post-AIA effective filing date (on or after March 16, 2013) are subject to the patentability requirements in AIA 35 U.S.C. 102 – 103 and subject to pre-AIA 35 U.S.C. 102(g).See MPEP § 2159 et seq.]

Jump to MPEP SourceKey Changes Under AIAAIA vs Pre-AIA PracticeAIA Effective Dates
Topic

AIA Effective Dates

1 rules
StatutoryInformativeAlways
[mpep-2138-01-59a88017a3f112ea5d97770d]
Patents with Mixed AIA and Pre-AIA Claims Subject to Both Laws
Note:
Patents containing claims from both pre-AIA (before March 16, 2013) and post-AIA (on or after March 16, 2013) are subject to the patentability requirements of both AIA and pre-AIA laws.

[Editor Note: This MPEP section has limited applicability to applications subject to examination under the first inventor to file (FITF) provisions of the AIA as set forth in 35 U.S.C. 100 (note). Patents and applications that contain (or contained at any time) at least one claim with a pre-AIA effective filing date (before March 16, 2013) and at least one claim with a post-AIA effective filing date (on or after March 16, 2013) are subject to the patentability requirements in AIA 35 U.S.C. 102 – 103 and subject to pre-AIA 35 U.S.C. 102(g).See MPEP § 2159 et seq.]

Jump to MPEP SourceAIA Effective DatesDetermining Whether Application Is AIA or Pre-AIAAIA Overview and Effective Dates
Topic

Pre-AIA 102(g) – Prior Invention (MPEP 2138)

1 rules
StatutoryInformativeAlways
[mpep-2138-01-98f458dd9cf2e51bb00fbcae]
Priority Determination for Invention
Note:
This rule outlines the basis for determining priority of invention between two parties under pre-AIA 35 U.S.C. 102(g).

Subsection (g) of pre-AIA 35 U.S.C. 102 is the basis of interference practice for determining priority of invention between two parties. See Bigham v. Godtfredsen, 857 F.2d 1415, 1416, 8 USPQ2d 1266, 1267 (Fed. Cir. 1988); Paulik v. Rizkalla, 760 F.2d 1270, 1276-81, 226 USPQ 224, 225 (Fed. Cir. 1985) (reviews the legislative history of the subsection in a concurring opinion by Judge Rich). 35 U.S.C. 135, 37 CFR Part 41, Subparts D and E and MPEP Chapter 2300. An interference is an inter partes proceeding directed at determining the first to invent as among the parties to the proceeding, involving two or more pending applications naming different inventors or one or more pending applications and one or more unexpired patents naming different inventors. The first of many to reduce an invention to practice around the same time will be the sole party to obtain a patent in some instances, Radio Corp. of America v. Radio Eng’g Labs., Inc., 293 U.S. 1, 2, 21 USPQ 353, 353-4 (1934), unless another was the first to conceive and couple a later-in-time reduction to practice with diligence from a time just prior to when the second conceiver entered the field to the first conceiver’s reduction to practice. Hull v. Davenport, 90 F.2d 103, 105, 33 USPQ 506, 508 (CCPA 1937). See the priority time charts below illustrating this point. Upon conclusion of an interference, subject matter claimed by the losing party that was the basis of the interference is rejected under pre-AIA 35 U.S.C. 102(g), unless the acts showing prior invention were not in this country.

Jump to MPEP SourcePre-AIA 102(g) – Prior Invention (MPEP 2138)Prior Art Under Pre-AIA 35 U.S.C. 102 (MPEP 2131-2138)AIA vs Pre-AIA 102 (MPEP 2151)
Topic

Determining Whether Application Is AIA or Pre-AIA

1 rules
StatutoryRequiredAlways
[mpep-2138-01-ab486441a5ff997340e2d2b3]
Requirement for Proper Inventorship
Note:
The rule requires that the true inventor be named before a patent can be granted, and allows rejection if an inventor has derived their invention from another.

It is noted that 35 U.S.C. 101 requires that whoever invents or discovers the claimed invention is the party that must be named as the inventor before a patent may be granted. Where it can be shown that a named inventor has “derived” an invention from another, a rejection under pre-AIA 35 U.S.C. 102(f) is proper if applicable. Ex parte Kusko, 215 USPQ 972, 974 (Bd. App. 1981) (“most, if not all, determinations under [pre-AIA] Section 102(f) involve the question of whether one party derived an invention from another”); Price v. Symsek, 988 F.2d 1187, 1190, 26 USPQ2d 1031, 1033 (Fed. Cir. 1993) (Although derivation and priority of invention both focus on inventorship, derivation addresses originality, i.e., who invented the subject matter, whereas priority focuses on which party invented the subject matter first.).

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIAPre-AIA 102(f) – Derivation (MPEP 2137)
Topic

Pre-AIA 102(f) – Derivation (MPEP 2137)

1 rules
StatutoryInformativeAlways
[mpep-2138-01-7203c603ba8aead49f53626a]
Derivation of Invention Must Be Proven First
Note:
The party claiming an invention must prove they did not derive it from another inventor before a patent can be granted.

It is noted that 35 U.S.C. 101 requires that whoever invents or discovers the claimed invention is the party that must be named as the inventor before a patent may be granted. Where it can be shown that a named inventor has “derived” an invention from another, a rejection under pre-AIA 35 U.S.C. 102(f) is proper if applicable. Ex parte Kusko, 215 USPQ 972, 974 (Bd. App. 1981) (“most, if not all, determinations under [pre-AIA] Section 102(f) involve the question of whether one party derived an invention from another”); Price v. Symsek, 988 F.2d 1187, 1190, 26 USPQ2d 1031, 1033 (Fed. Cir. 1993) (Although derivation and priority of invention both focus on inventorship, derivation addresses originality, i.e., who invented the subject matter, whereas priority focuses on which party invented the subject matter first.).

Jump to MPEP SourcePre-AIA 102(f) – Derivation (MPEP 2137)Determining Whether Application Is AIA or Pre-AIA
Topic

Pre-AIA 102(c) – Abandonment (MPEP 2134)

1 rules
StatutoryInformativeAlways
[mpep-2138-01-83ec30bb736a509d264c8841]
Invention Priority and Abandonment, Suppression, Concealment
Note:
This rule discusses how invention priority is determined in interference proceedings and the conditions under which an inventor can claim that their invention was not abandoned, suppressed, or concealed.

The following priority time charts illustrate the award of invention priority in several situations. The time charts apply to interference proceedings and are also applicable to declarations or affidavits filed under 37 CFR 1.131 to antedate references which are available as prior art under pre-AIA 35 U.S.C. 102(a) or 102(e). Note, however, in the context of 37 CFR 1.131, an inventor does not have to show that the invention was not abandoned, suppressed, or concealed from the time of an actual reduction to practice to a constructive reduction to practice because the length of time taken to file a patent application after an actual reduction to practice is generally of no consequence except in an interference proceeding. Paulik v. Rizkalla, 760 F.2d 1270, 226 USPQ 224 (Fed. Cir. 1985). See the discussion of abandonment, suppression, and concealment in MPEP § 2138.03.

Jump to MPEP Source · 37 CFR 1.131Pre-AIA 102(c) – Abandonment (MPEP 2134)Actual Reduction to Practice
Topic

Abandonment & Revival

1 rules
StatutoryPermittedAlways
[mpep-2138-01-340d7786e71e3d80a2da7e5d]
Awards Priority to Inventor A if Diligently Reduced Invention to Practice Before B
Note:
In an interference, inventor A is awarded priority over B if A can show reasonable diligence from a point just before B’s conception until the invention was constructively reduced to practice, without abandoning, suppressing, or concealing it.

A is awarded priority in an interference if A can show reasonable diligence from T D (a point just prior to B’s conception) until Ra in the absence of abandonment, suppression, or concealment from Ra to Rc, because A conceived the invention before B, diligently actually reduced the invention to practice (after B reduced the invention to practice), and did not abandon, suppress, or conceal the invention after actually reducing the invention to practice and before constructively reducing the invention to practice.

Jump to MPEP SourceAbandonment & RevivalInterference Proceedings (Pre-AIA)
Topic

35 U.S.C. 102 – Novelty / Prior Art

1 rules
StatutoryInformativeAlways
[mpep-2138-01-2272f75b534c86472c842713]
Claim Anticipation or Obviousness Requires Interference
Note:
A claim is considered to be the same patentable invention if it is either anticipated by or obvious in view of another claim, requiring an interference rather than an affidavit under ex parte practice.

Interference practice operates to the exclusion of ex parte practice under 37 CFR 1.131 which permits an inventor to show an actual date of invention prior to the effective date of a reference or activity applied under pre-AIA 35 U.S.C. 102 or 103, as long as the reference is not a statutory bar under pre-AIA 35 U.S.C. 102(b) or a U.S. patent application publication claiming the same patentable invention. Ex parte Standish, 10 USPQ2d 1454, 1457 (Bd. Pat. App. & Inter. 1988) (An application claim to the “same patentable invention” claimed in a domestic patent requires interference rather than an affidavit under 37 CFR 1.131 to antedate the patent. The term “same patentable invention” encompasses a claim that is either anticipated by or obvious in view of the subject matter recited in the patent claim.). Subject matter which is prior art under pre-AIA 35 U.S.C. 102(g) and is subject to an interference is not open to further inquiry under 37 CFR 1.131 during the interference proceeding.

Jump to MPEP Source · 37 CFR 1.131Novelty / Prior ArtConception and Reduction to PracticeAIA Effective Dates
Topic

Obviousness Under AIA (MPEP 2158)

1 rules
StatutoryPermittedAlways
[mpep-2138-01-8f819160b14adcc8e3ebbecb]
Lost Interference Subject Not Statutory Prior Art
Note:
A lost interference count’s subject matter cannot be used as statutory prior art, but can be combined with other references under pre-AIA 103 if it meets pre-AIA 102 criteria.

Loss of an interference count alone does not make its subject matter statutory prior art to losing party; however, lost count subject matter that is available as prior art under pre-AIA 35 U.S.C. 102 may be used alone or in combination with other references under pre-AIA 35 U.S.C. 103. But see In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. Cir. 1992) (Under the principles of res judicata and collateral estoppel, Deckler was not entitled to claims that were patentably indistinguishable from the claim lost in interference even though the subject matter of the lost count was not available for use in an obviousness rejection under 35 U.S.C. 103.).

Jump to MPEP SourceObviousness Under AIA (MPEP 2158)Obviousness Under Pre-AIA (MPEP 2141-2146)AIA vs Pre-AIA Practice
Topic

Estoppel After Judgment

1 rules
StatutoryInformativeAlways
[mpep-2138-01-b09683c6953f2f8654b9ace4]
Lost Interference Count Subject Matter Not Prior Art
Note:
Under res judicata and collateral estoppel, claims patentably indistinguishable from a lost interference count cannot be asserted even if the subject matter was not available for an obviousness rejection.

Loss of an interference count alone does not make its subject matter statutory prior art to losing party; however, lost count subject matter that is available as prior art under pre-AIA 35 U.S.C. 102 may be used alone or in combination with other references under pre-AIA 35 U.S.C. 103. But see In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. Cir. 1992) (Under the principles of res judicata and collateral estoppel, Deckler was not entitled to claims that were patentably indistinguishable from the claim lost in interference even though the subject matter of the lost count was not available for use in an obviousness rejection under 35 U.S.C. 103.).

Jump to MPEP SourceEstoppel After JudgmentObviousnessObviousness Under AIA (MPEP 2158)

Citations

Primary topicCitation
AIA Effective Dates
Key Changes Under AIA
35 U.S.C. § 100
Determining Whether Application Is AIA or Pre-AIA
Pre-AIA 102(f) – Derivation (MPEP 2137)
35 U.S.C. § 101
35 U.S.C. 102 – Novelty / Prior Art
AIA Effective Dates
Antedating Reference – Pre-AIA (MPEP 2136.05)
Conception and Reduction to Practice
Diligence Requirement
Estoppel After Judgment
Key Changes Under AIA
Obviousness Under AIA (MPEP 2158)
Pre-AIA 102(g) – Prior Invention (MPEP 2138)
35 U.S.C. § 102
Actual Reduction to Practice
Antedating Reference – Pre-AIA (MPEP 2136.05)
Pre-AIA 102(c) – Abandonment (MPEP 2134)
35 U.S.C. § 102(a)
35 U.S.C. 102 – Novelty / Prior Art
Antedating Reference – Pre-AIA (MPEP 2136.05)
Conception and Reduction to Practice
35 U.S.C. § 102(b)
Determining Whether Application Is AIA or Pre-AIA
Pre-AIA 102(f) – Derivation (MPEP 2137)
35 U.S.C. § 102(f)
35 U.S.C. 102 – Novelty / Prior Art
AIA Effective Dates
Antedating Reference – Pre-AIA (MPEP 2136.05)
Conception and Reduction to Practice
Diligence Requirement
Key Changes Under AIA
Pre-AIA 102(g) – Prior Invention (MPEP 2138)
35 U.S.C. § 102(g)
Estoppel After Judgment
Obviousness Under AIA (MPEP 2158)
35 U.S.C. § 103
Antedating Reference – Pre-AIA (MPEP 2136.05)
Conception and Reduction to Practice
Diligence Requirement
Pre-AIA 102(g) – Prior Invention (MPEP 2138)
35 U.S.C. § 135
35 U.S.C. 102 – Novelty / Prior Art
Actual Reduction to Practice
Antedating Reference – Pre-AIA (MPEP 2136.05)
Conception and Reduction to Practice
Interference Proceedings (Pre-AIA)
Pre-AIA 102(c) – Abandonment (MPEP 2134)
37 CFR § 1.131
Actual Reduction to Practice
Antedating Reference – Pre-AIA (MPEP 2136.05)
Pre-AIA 102(c) – Abandonment (MPEP 2134)
MPEP § 2138.03
AIA Effective Dates
Key Changes Under AIA
MPEP § 2159
Antedating Reference – Pre-AIA (MPEP 2136.05)
Conception and Reduction to Practice
Diligence Requirement
Pre-AIA 102(g) – Prior Invention (MPEP 2138)
Hull v. Davenport, 90 F.2d 103, 105, 33 USPQ 506, 508 (CCPA 1937)
Estoppel After Judgment
Obviousness Under AIA (MPEP 2158)
In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. Cir. 1992)
Actual Reduction to Practice
Antedating Reference – Pre-AIA (MPEP 2136.05)
Pre-AIA 102(c) – Abandonment (MPEP 2134)
Paulik v. Rizkalla, 760 F.2d 1270, 226 USPQ 224 (Fed. Cir. 1985)
Determining Whether Application Is AIA or Pre-AIA
Pre-AIA 102(f) – Derivation (MPEP 2137)
Price v. Symsek, 988 F.2d 1187, 1190, 26 USPQ2d 1031, 1033 (Fed. Cir. 1993)
Antedating Reference – Pre-AIA (MPEP 2136.05)
Conception and Reduction to Practice
Diligence Requirement
Pre-AIA 102(g) – Prior Invention (MPEP 2138)
See Bigham v. Godtfredsen, 857 F.2d 1415, 1416, 8 USPQ2d 1266, 1267 (Fed. Cir. 1988)

Source Text from USPTO’s MPEP

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

BlueIron Last Updated: 2026-01-10