Interference Estoppel

Interference Estoppel

If a party loses on an issue, it may not re-litigate the issue before the examiner or in a subsequent Board of Patent Appeals and Interferences (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[ii].

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[iii]. Second, a losing party is procedurally barred from seeking from the examiner relief that could have been–but was not–sought in the interference[iv]. 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[v].

Interference estoppel “by judgment” applies where “a losing party in a previous interference between the same parties” tries to patent a claim “not patentably distinct from the counts in issue in that [prior] interference[vi]. Losing priority judgment in an interference proceeding bars the loser from obtaining a patent containing claims that are patentably indistinguishable from the claims corresponding to the lost count[vii].

Unsuccessful efforts to add a count do not prevent estoppel by judgment. Where the prior judgment between the same parties is not strictly res judicata[viii] because it resolves a different and distinct issue [e.g., a patentably distinct count], that judgment may nonetheless create an estoppel as to matters actually in issue or points controverted[ix].


[ii] Estoppel Within the Office, MPEP 2308.03[iii] In re Deckler, 977 F.2d 1449, 24 USPQ2d 1448 (Fed. Cir. 1992); Ex parte Tytgat, 225 USPQ 907 (Bd. Pat. App. & Inter. 1985)

[iv] 37 CFR 41.127(a)(1)

[v] Ex parte Kimura, 55 USPQ2d 1537 (Bd. Pat. App. & Inter. 2000)

[vi] Woods v. Tsuchiya, 754 F.2d 1571, 1579 (Fed. Cir. 1985)

[vii] MPEP § 2308.03 (9th ed. March 2014)

[viii] Res judicata is literally “a matter judged”. Res judicata is the principle that a matter may not, generally, be relitigated once it has been judged on the merits.

Res judicata encompasses limits on both the claims and the issues that may be raised in subsequent proceedings:

Claim preclusion is the principle once a cause of action has been litigated, it may not be relitigated.

Bar: A losing plaintiff is barred from re-suing a winning defendant on the same cause of action. (Scenario: Plaintiff P unsuccessfully sues Defendant D on Cause of action C. P may not try for better luck by initiating a new lawsuit against D on C.)

Merger: A winning plaintiff may not re-sue a losing defendant. (Scenario: P successfully sues D on C. P may not again sue D on C to try to recover more damages.)

Issue preclusion (Collateral estoppel): Once an issue of fact has been determined in a proceeding between two parties, the parties may not relitigate that issue even in a proceeding on a different cause of action. (Scenario: P sues D on C. P sues D on C1. Element E, which was determined in the first trial, is common to C and C1. At the second trial, P and D cannot attempt to get a different disposition of E.)

[ix] Stoudt v. Guggenheim, 651 F.2d 760 (CCPA 1981)

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