Under the doctrine of res judicata (or claim preclusion), the entry of a final judgment “on the merits” of a claim (i.e., cause of action) in a proceeding serves to preclude relitigating the same claim in a subsequent proceeding between the parties or their privies. Chromalloy American Corp. v. Kenneth Gordon, Ltd., 736 F.2d 694 (Fed. Cir. 1984); see also Sharp KK v. Thinksharp, Inc., 448 F.3d 1368, 1372 (Fed. Cir. 2006) (“The purpose of res judicata is salutary, for it protects a party from being required to relitigate the same issue against the same party in a separate action.”). “[S]o long as opposing parties had an adequate opportunity to litigate disputed issues of fact, res judicata is properly applied to decisions of an administrative agency acting in a ‘judicial capacity.'” Kremer v. Chem. Constr. Corp., 456 U.S. 461, 485 n.26 (1982). 

As set forth in Jet, Inc. v. Sewage Aeration Sys., 223 F.3d 1360, 1363 (Fed. Cir. 2000), a second suit is barred by res judicata or claim preclusion if:

1. the parties (or their privies) are identical;
2. there has been an earlier final judgment on the merits of a claim; and
3. the second claim is based on the same set of transactional facts as the claim in the first proceeding.

For the third prong, the issue is whether the claim comprises the same “core [or nucleus] of operative facts” or are “based on the same, or nearly the same, factual allegations” as those asserted in the first proceeding. Jet, Inc., 223 F.3d at 1363 (finding petitioner's trademark infringement claim in federal district court was not based on the same set of factual allegations as its petition to cancel defendant's federally registered mark). For a trademark, this includes consideration of:

1. whether the marks involved in the prior proceeding are the same marks, in terms of commercial impression, as the marks involved in this proceeding; and
2. whether the evidence of likelihood of confusion between the marks in the prior proceeding would be identical to the evidence of likelihood of confusion in this proceeding.

See Institut Nat'l Des Appellations d'Origine v. Brown-Forman Corp., No. 91097417, 1998 TTAB LEXIS 122, at *67) (Board denied opposer's motion to amend to add a res judicata claim as futile); see also Be Sport, Inc. v. Al-Jazeera Satellite Channel, No. 91213743, 2015 TTAB LEXIS 259, at *9 (Board denied applicant's motion for leave to file an amended answer to assert an affirmative defense of res judicata as futile)

The TTAB found that that claim preclusion (i.e., res judicata) applied in Mars, Incorporated v. PAGS Inc., Opposition No. 91263504 (TTAB Sept. 16, 2026), based on an earlier opposition between the same parties, and PAGS later filed a second application for a sightly different mark in connection with narrowed services, but those changes were insufficient to avoid the judgment from the prior successful opposition by Mars against that first mark. 

Years earlier, the TTAB previously had sustained Opposer Mars' opposition to registration of the mark PET AGREE for “wholesale and retail supply store services featuring pet grooming supplies; online wholesale and retail services featuring pet grooming supplies," concluding that confusion is likely with the registered mark PEDIGREE for pet food. 

The new application for PET-AGREE GROOMING SUPPLIES identified narrower services of "wholesale supply store services for pet grooming supplies in the business to business market directed to pet professionals and commercial pet groomers, expressly excluding pet food, pet treats and products fed to pets and animals and excluding bowls, cups and containers for pet food, pet treats and products fed to pets and animals." Mars opposed the new application on the same grounds (likelihood of confusion and dilution) as in the prior opposition but also asserted offensive claim preclusion (i.e., res judicata). See Sharp KK, 448 F.3d at 1371 (discussion of doctrine of offensive res judicata); see also Flame & Wax, Inc. v. Laguna Candles, LLC, No. 92072343, 2022 TTAB LEXIS 272, at *43 (“This case involves offensive, not defensive, claim preclusion - it is the plaintiff in the proceeding that is asserting claim preclusion.”).

The TTAB found that the new mark, PET-AGREE GROOMING SUPPLIES, created the same commercial impression as the earlier PET-AGREE mark, noting that PET-AGREE was the only source-indicating element since the newly added wording GROOMING SUPPLIES was generic.

The narrowed services also did not present a new set of transactional facts for purposes of res judicata.

The services identified in the Prior Opposition and those in the present application are in part legally identical. This is because the amended identification merely narrows, rather than changes, the prior services by removing the retail services and by adding language directed to the business-to-business market, pet professionals and commercial pet groomers. This new language restates, in more specific terms, services that were already encompassed by the broader prior identification. The Board's judgment against Applicant in the Prior Opposition was based on a broader identification of services, and that judgment necessarily extends to any and all identified services under that broader identification. See J.I. Case Co. v. F.L. Indus., No. 70765, 1986 TTAB LEXIS 112, at *9-11. “Applicant may not avoid the preclusive effect of this prior judgment by merely providing a narrower, or ‘more focused,' identification of services, if those services remain encompassed by the broader identification of services and are therefore essentially legally identical.”

     Furthermore, the additional language expressly excluding Opposer's goods of “pet food, pet treats and products fed to pets and animals and excluding bowls, cups and containers for pet food, pet treats and products fed to pets and animals,” does nothing to change the core nucleus of facts. The Board expressly recognized in the Prior Opposition that grooming supplies and pet food were not identical. For this reason, Applicant's restriction to its identification of services to expressly now exclude Opposer's goods does nothing to alter the fundamental inquiry of whether Applicant's services are nevertheless related to Opposer's goods. As a result, we find that contrary to Applicant's assertions, this issue was previously adjudicated on the same transactional facts.

And the new limitations set forth in the application on the channels of trade and classes of purchasers did not change the analysis because Opposer's registrations still remained unrestricted as to purchasers. And the TTAB continued to apply the well-established principle that Opposer's goods presumptively move in all normal trade channels and to consumers that purchase such goods, citing Levi Strauss & Co. v. Abercrombie & Fitch Trading Co., 719 F.3d 1367, 1373 (Fed. Cir. 2013).

The TTABlog noted: "It's not that easy to end-run a prior adverse judgment after a full trial on the merits."