MPEP § 2308.03 — Estoppel Within the Office (Annotated Rules)

§2308.03 Estoppel Within the Office

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

This page consolidates and annotates all enforceable requirements under MPEP § 2308.03, 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.

Estoppel Within the Office

This section addresses Estoppel Within the Office. Contains: 4 requirements, 1 prohibition, 1 guidance statement, 2 permissions, and 10 other statements.

Key Rules

Topic

35 U.S.C. 103 – Obviousness

11 rules
StatutoryInformativeAlways
[mpep-2308-03-268f78fbd64f6dbacb881fb3]
Claim Must Be Obvious Over X for Estoppel
Note:
A continuing application claim must be rejected if it would have been obvious over subject matter X, demonstrating why the claim is obvious using X as prior art.

Same facts as Example 1 except the applicant files a continuing application with a claim to subject matter that would have been obvious in view of subject matter X. The claim must be rejected as estopped on the merits by the applicant’s loss in the interference, but the examiner must demonstrate why the claim would have been obvious if subject matter X is assumed to be prior art.

StatutoryRequiredAlways
[mpep-2308-03-61ef67f17a560b754460ab55]
Claim Must Be Rejected as Obvious if X Is Prior Art
Note:
The claim must be rejected due to estoppel because it would have been obvious in view of subject matter X, which is considered prior art.

Same facts as Example 1 except the applicant files a continuing application with a claim to subject matter that would have been obvious in view of subject matter X. The claim must be rejected as estopped on the merits by the applicant’s loss in the interference, but the examiner must demonstrate why the claim would have been obvious if subject matter X is assumed to be prior art.

StatutoryInformativeAlways
[mpep-2308-03-05a65ff3ed1fbc9c1a6a2992]
Amendment During Interference Must Be Made
Note:
The applicant must amend claim 1 during the interference to avoid estoppel if the amendment would have been unpatentable.

The applicant’s claim 1 was held unpatentable during the interference. The applicant could have moved, but did not move, to amend the claim. The applicant files a continuing application with an amended claim 1. If the subject matter of the amended claim would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped. Whether the amendment is sufficient to overcome the ground for unpatentability or not, the time to have amended the claim was during the interference.

StatutoryInformativeAlways
[mpep-2308-03-5fa569ee07ebe32a6b37053d]
Amendment During Interference Required
Note:
The applicant must have amended the claim during interference to avoid procedural estoppel, even if the amendment would not overcome prior art.

The applicant’s claim 1 was held unpatentable during the interference. The applicant could have moved, but did not move, to amend the claim. The applicant files a continuing application with an amended claim 1. If the subject matter of the amended claim would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped. Whether the amendment is sufficient to overcome the ground for unpatentability or not, the time to have amended the claim was during the interference.

StatutoryInformativeAlways
[mpep-2308-03-9dbc152638e3a65230e7866d]
Amended Claim Procedurally Estopped During Interference
Note:
If an amended claim in a continuing application would have been anticipated or obvious during the interference, it must be rejected as procedurally estopped.

The applicant’s claim 1 was held unpatentable during the interference. The applicant could have moved, but did not move, to amend the claim. The applicant files a continuing application with an amended claim 1. If the subject matter of the amended claim would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped. Whether the amendment is sufficient to overcome the ground for unpatentability or not, the time to have amended the claim was during the interference.

StatutoryRequiredAlways
[mpep-2308-03-ed18dab2fe92f1f434c4d1c8]
Amended Claim Procedurally Estopped
Note:
If an amended claim would have been anticipated or obvious during interference, it must be rejected as procedurally estopped.

The applicant’s claim 1 was held unpatentable during the interference. The applicant could have moved, but did not move, to amend the claim. The applicant files a continuing application with an amended claim 1. If the subject matter of the amended claim would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped. Whether the amendment is sufficient to overcome the ground for unpatentability or not, the time to have amended the claim was during the interference.

StatutoryInformativeAlways
[mpep-2308-03-10f5cbacf50cfc9e35905198]
Amendment Must Be Made During Interference
Note:
The claim must be amended during the interference to overcome unpatentability, regardless of whether the amendment is sufficient.

The applicant’s claim 1 was held unpatentable during the interference. The applicant could have moved, but did not move, to amend the claim. The applicant files a continuing application with an amended claim 1. If the subject matter of the amended claim would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped. Whether the amendment is sufficient to overcome the ground for unpatentability or not, the time to have amended the claim was during the interference.

StatutoryInformativeAlways
[mpep-2308-03-0a9df8ac6f67315170ee38a9]
Claim Amendment Estoppel Applies After Denial
Note:
If an amended claim would have been anticipated or obvious, it must be rejected even if the amendment motion was denied.

Same situation as Example 6 except the applicant did move to amend the claim, but the motion was denied. The result is the same as in Example 6. If the subject matter of the amended claim would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped. The applicant’s lack of success on the motion does not prevent the estoppel from applying to the claim.

StatutoryInformativeAlways
[mpep-2308-03-ff9c2897a6d9abf4ca11f3b5]
Claim Anticipation or Obviousness Estoppels Despite Motion Denial
Note:
If amended claim subject matter is anticipated or obvious, it must be rejected even if amendment motion was denied.

Same situation as Example 6 except the applicant did move to amend the claim, but the motion was denied. The result is the same as in Example 6. If the subject matter of the amended claim would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped. The applicant’s lack of success on the motion does not prevent the estoppel from applying to the claim.

StatutoryRequiredAlways
[mpep-2308-03-cfabe835176019cc8d220cdd]
Amended Claim Procedurally Estopped If Anticipated or Obvious
Note:
If the amended claim's subject matter would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped.

Same situation as Example 6 except the applicant did move to amend the claim, but the motion was denied. The result is the same as in Example 6. If the subject matter of the amended claim would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped. The applicant’s lack of success on the motion does not prevent the estoppel from applying to the claim.

StatutoryInformativeAlways
[mpep-2308-03-873b975d8ac7616947386f45]
Estoppel Applies Despite Failed Amendment Motion
Note:
If an amended claim would have been anticipated or obvious, estoppel applies even if the amendment motion was denied.

Same situation as Example 6 except the applicant did move to amend the claim, but the motion was denied. The result is the same as in Example 6. If the subject matter of the amended claim would have been anticipated or obvious in view of a count of the interference, it must be rejected as procedurally estopped. The applicant’s lack of success on the motion does not prevent the estoppel from applying to the claim.

Topic

Estoppel After Judgment

8 rules
StatutoryInformativeAlways
[mpep-2308-03-4e14a0805a2b0b3f95794b92]
Two Types of Interference Estoppel Prohibited
Note:
A losing party is barred from seeking claims that would have been anticipated or relief not previously sought in an interference.

There are two main types of interference estoppel. First, a losing party is barred on the merits from seeking a claim that would have been anticipated or rendered obvious by the subject matter of the lost count. See In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. Cir. 1992); and Ex parte Tytgat, 225 USPQ 907 (Bd. Pat. App. & Inter. 1985). Second, a losing party is procedurally barred from seeking from the examiner relief that could have been–but was not–sought in the interference. See 37 CFR 41.127(a)(1); and Ex parte Kimura, 55 USPQ2d 1537 (Bd. Pat. App. & Inter. 2000) (reissue applicant estopped to claim compound when patentability of that compound could have been put in issue in interference where opponent’s application also described compound).

Jump to MPEP Source · 37 CFR 41.127(a)(1)Estoppel After JudgmentPTAB Contested Case ProceduresReissue Patent Practice
StatutoryInformativeAlways
[mpep-2308-03-9c74c6ed1dfb29833c6713ef]
Estoppel After Judgment In Interference Proceedings
Note:
A losing party in an interference proceeding is barred from seeking relief that could have been but was not sought during the interference.

There are two main types of interference estoppel. First, a losing party is barred on the merits from seeking a claim that would have been anticipated or rendered obvious by the subject matter of the lost count. See In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. Cir. 1992); and Ex parte Tytgat, 225 USPQ 907 (Bd. Pat. App. & Inter. 1985). Second, a losing party is procedurally barred from seeking from the examiner relief that could have been–but was not–sought in the interference. See 37 CFR 41.127(a)(1); and Ex parte Kimura, 55 USPQ2d 1537 (Bd. Pat. App. & Inter. 2000) (reissue applicant estopped to claim compound when patentability of that compound could have been put in issue in interference where opponent’s application also described compound).

Jump to MPEP Source · 37 CFR 41.127(a)(1)Estoppel After JudgmentPTAB Contested Case ProceduresReissue Patent Practice
StatutoryInformativeAlways
[mpep-2308-03-8a9b02d68f3df66c10d08bc1]
Loss of Priority Estoppels Claims
Note:
If an applicant loses on priority for a count, all corresponding claims are automatically disposed of and any new claim to the same subject matter is estopped from being allowed.

The applicant lost on priority for a count drawn to subject matter X. The Board’s judgment automatically disposed of all of the applicant’s claims corresponding to the count. The applicant files a continuing application with a claim to subject matter X. The claim must be rejected as estopped on the merits by the applicant’s loss in the interference.

Jump to MPEP SourceEstoppel After JudgmentPTAB JurisdictionPTAB Contested Case Procedures
StatutoryInformativeAlways
[mpep-2308-03-af366e8094dc1941a270b5e3]
Claim Corresponding to Lost Count Automatically Disposed
Note:
If the applicant loses on a count, all claims related to that count are automatically disposed of in an interference case.

The applicant lost on priority for a count drawn to subject matter X. The Board’s judgment automatically disposed of all of the applicant’s claims corresponding to the count. The applicant files a continuing application with a claim to subject matter X. The claim must be rejected as estopped on the merits by the applicant’s loss in the interference.

Jump to MPEP SourceEstoppel After JudgmentPTAB JurisdictionPTAB Contested Case Procedures
StatutoryRequiredAlways
[mpep-2308-03-6858dadbab80bb374b6e4a19]
Claim Must Be Rejected Due to Prior Estoppel
Note:
A claim in a continuing application that corresponds to subject matter X must be rejected as estopped due to the applicant's prior loss in an interference.

The applicant lost on priority for a count drawn to subject matter X. The Board’s judgment automatically disposed of all of the applicant’s claims corresponding to the count. The applicant files a continuing application with a claim to subject matter X. The claim must be rejected as estopped on the merits by the applicant’s loss in the interference.

Jump to MPEP SourceEstoppel After JudgmentPTAB JurisdictionPTAB Contested Case Procedures
StatutoryPermittedAlways
[mpep-2308-03-b4d33700dfa3fb79955c8cf6]
Claim Must Correspond to Count During Interference
Note:
During an interference, the applicant must be allowed to show that the claim does not correspond to the count. If denied, procedural estoppel does not apply if the Board prevented relief.

Same facts as Example 4 except that during the interference the applicant timely requested, but was not permitted, to show the claim did not correspond to the count. The examiner may determine in light of the new showing whether the lost count would have anticipated or rendered obvious the subject matter of the claim. The procedural estoppel does not apply if, through no fault of the applicant, the Board prevented the applicant from seeking relief during the interference.

Jump to MPEP SourceEstoppel After JudgmentPTAB JurisdictionPTAB Contested Case Procedures
StatutoryPermittedAlways
[mpep-2308-03-8cf6edd7dd386e7131bbfe31]
Examiner May Reconsider Lost Count After New Showing
Note:
The examiner can reassess whether the lost count would have anticipated or rendered obvious the claim's subject matter after new evidence is presented.

Same facts as Example 4 except that during the interference the applicant timely requested, but was not permitted, to show the claim did not correspond to the count. The examiner may determine in light of the new showing whether the lost count would have anticipated or rendered obvious the subject matter of the claim. The procedural estoppel does not apply if, through no fault of the applicant, the Board prevented the applicant from seeking relief during the interference.

Jump to MPEP SourceEstoppel After JudgmentPTAB JurisdictionPTAB Contested Case Procedures
StatutoryInformativeAlways
[mpep-2308-03-4f4f0fc4d9f2a4468c55483a]
Procedural Estoppel Does Not Apply If Board Prevented Relief During Interference
Note:
The procedural estoppel does not apply if the Board prevented the applicant from seeking relief during the interference, despite no fault of the applicant.

Same facts as Example 4 except that during the interference the applicant timely requested, but was not permitted, to show the claim did not correspond to the count. The examiner may determine in light of the new showing whether the lost count would have anticipated or rendered obvious the subject matter of the claim. The procedural estoppel does not apply if, through no fault of the applicant, the Board prevented the applicant from seeking relief during the interference.

Jump to MPEP SourceEstoppel After JudgmentPTAB JurisdictionPTAB Contested Case Procedures
Topic

PTAB Contested Case Procedures

4 rules
StatutoryInformativeAlways
[mpep-2308-03-6fcbf8ba8e1c5df13c7227aa]
Losing Party Barred from Anticipating Lost Claim
Note:
A losing party in an interference cannot seek a claim that would have been anticipated by the lost count.

There are two main types of interference estoppel. First, a losing party is barred on the merits from seeking a claim that would have been anticipated or rendered obvious by the subject matter of the lost count. See In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. Cir. 1992); and Ex parte Tytgat, 225 USPQ 907 (Bd. Pat. App. & Inter. 1985). Second, a losing party is procedurally barred from seeking from the examiner relief that could have been–but was not–sought in the interference. See 37 CFR 41.127(a)(1); and Ex parte Kimura, 55 USPQ2d 1537 (Bd. Pat. App. & Inter. 2000) (reissue applicant estopped to claim compound when patentability of that compound could have been put in issue in interference where opponent’s application also described compound).

Jump to MPEP Source · 37 CFR 41.127(a)(1)PTAB Contested Case ProceduresEstoppel After JudgmentObviousness
StatutoryInformativeAlways
[mpep-2308-03-2f02391e29cb7108e456694d]
Losing Party Prohibited from Seeking Examiner Relief Not Sought in Interference
Note:
A losing party in an interference is barred from seeking examiner relief that could have been but was not sought during the interference.

There are two main types of interference estoppel. First, a losing party is barred on the merits from seeking a claim that would have been anticipated or rendered obvious by the subject matter of the lost count. See In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. Cir. 1992); and Ex parte Tytgat, 225 USPQ 907 (Bd. Pat. App. & Inter. 1985). Second, a losing party is procedurally barred from seeking from the examiner relief that could have been–but was not–sought in the interference. See 37 CFR 41.127(a)(1); and Ex parte Kimura, 55 USPQ2d 1537 (Bd. Pat. App. & Inter. 2000) (reissue applicant estopped to claim compound when patentability of that compound could have been put in issue in interference where opponent’s application also described compound).

Jump to MPEP Source · 37 CFR 41.127(a)(1)PTAB Contested Case ProceduresEstoppel After JudgmentReissue Patent Practice
StatutoryRecommendedAlways
[mpep-2308-03-ba75e97e63af78a8d0f32f24]
IPS Consultation Before Allowing Claim Amendments for Losing Party
Note:
Examiners must consult an Interference Practice Specialist before permitting claim amendments for a losing party during post-interference examination.

The examiner should consult with an Interference Practice Specialist (IPS) before allowing a claim to a losing party that was added or amended during post-interference examination.

Jump to MPEP SourcePTAB Contested Case ProceduresEstoppel After JudgmentInterference Proceedings (Pre-AIA)
MPEP GuidanceProhibitedAlways
[mpep-2308-03-f2120c12ce391b45b8bfbf01]
Issue Estoppel After Loss Before Examiner
Note:
A party that loses on an issue cannot re-litigate it before the examiner or in a subsequent Board proceeding unless expressly prevented during the interference.

If a party loses on an issue, it may not re-litigate the issue before the examiner or in a subsequent Board proceeding. The time for the party to make all pertinent arguments is during the interference, unless the Board expressly prevented the party from litigating the issue during the interference.

Jump to MPEP SourcePTAB Contested Case ProceduresEstoppel After JudgmentPTAB Jurisdiction
Topic

PTAB Jurisdiction

2 rules
MPEP GuidanceInformativeAlways
[mpep-2308-03-9e51d2724f21c6eb7194cb9d]
Issue Must Not Be Relitigated Before Examiner Or Board
Note:
A party that loses an issue may not re-litigate it before the examiner or in a subsequent Board proceeding unless expressly prevented during interference.

If a party loses on an issue, it may not re-litigate the issue before the examiner or in a subsequent Board proceeding. The time for the party to make all pertinent arguments is during the interference, unless the Board expressly prevented the party from litigating the issue during the interference.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresEstoppel After Judgment
MPEP GuidanceInformativeAlways
[mpep-2308-03-0ef8b9e3cdf2d3f48facc179]
Arguments Must Be Presented During Interference Unless Board Prevents
Note:
Parties must present all relevant arguments during an interference unless the Board explicitly prevents them from litigating a specific issue.

If a party loses on an issue, it may not re-litigate the issue before the examiner or in a subsequent Board proceeding. The time for the party to make all pertinent arguments is during the interference, unless the Board expressly prevented the party from litigating the issue during the interference.

Jump to MPEP SourcePTAB JurisdictionPTAB Contested Case ProceduresEstoppel After Judgment

Citations

Primary topicCitation
Estoppel After Judgment
PTAB Contested Case Procedures
37 CFR § 41.127(a)(1)
Estoppel After Judgment
PTAB Contested Case Procedures
In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. Cir. 1992)

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