IP Law Daily, TECHNOLOGY/INTERNET—S.D.N.Y.: Google barred from relitigating core monopoly findings in ad tech MDL, (Oct 29, 2025)

By Martin A. Steinberg, J.D.

Google allegedly monopolized multiple layers of the digital advertising technology stack by using exclusionary agreements, self-preferencing, and auction practices engineered to favor its own platforms.

In an antitrust class action brought by publishers and advertisers, the federal district court in New York City partially granted a motion for summary judgment, holding that Google was precluded from relitigating key factual findings previously decided against it in the recent bench trial in the Eastern District of Virginia brought by the Department of Justice. Applying offensive non-mutual issue preclusion, the court determined that the Virginia judgment already established that Google held monopoly power in specific digital advertising markets and maintained that power through exclusionary conduct. The court declined to extend preclusion to issues the Virginia court did not directly decide—such as broader market definitions, class-wide impact, and damages—which remain open for litigation. The ruling, therefore, significantly narrows the issues for trial, preventing Google from re-arguing core questions about its dominance and conduct in the digital advertising ecosystem while allowing disputes over market scope and remedies to proceed (In Re Google Digital Advertising Antitrust Litigation, No. 1:21-cv-03446-PKC (S.D.N.Y. Oct. 27, 2025)).

The moving plaintiffs are Associated Newspapers Ltd. and Mail Media, Inc. (together, the “Daily Mail”), Gannett Co., Inc., Inform, Inc., a group of named publisher plaintiffs proceeding as representatives of a putative class of publishers (the “Publishers”), and at least one advertiser proceeding as a representative of a putative class of advertisers (the “Advertisers”). Each moving plaintiff names Alphabet Inc., Google’s parent, as a defendant, and the Publishers and Inform also named YouTube LLC. Google was the sole defendant in the Eastern District of Virginia action, and the issue-preclusion ruling addressed here applies only to Google.

In August 2021, the Judicial Panel on Multidistrict Litigation centralized numerous actions challenging Google’s digital advertising practices in this MDL in the Southern District of New York. The litigation includes suits brought by state attorneys general, putative publisher and advertiser classes, and individual plaintiffs, all alleging that Google used its control over ad-tech tools to restrain competition and inflate prices. The court selected the State Plaintiffs’ Third Amended Complaint as the bellwether for briefing on Google’s motion to dismiss, and in September 2022, granted that motion in part and denied it in part. Related private complaints were subsequently amended, and additional dismissal motions were resolved through 2023–2024.

Meanwhile, in January 2023, the U.S. Department of Justice and several states filed a parallel enforcement action in the Eastern District of Virginia involving the same ad-tech markets and theory of monopolization. That action proceeded to a bench trial, resulting in findings that Google unlawfully monopolized key digital advertising markets, findings that the moving plaintiffs here now seek to apply through offensive non-mutual issue preclusion.

The Publishers sought certification of (1) a class of U.S. publishers allegedly harmed through fees or reduced revenue in Google’s AdX exchange, and (2) a class alleging similar harm relating to Google’s AdSense platform. The advertisers sought certification of a class of advertisers who purchased display ads on third-party websites using Google Ads.

Issue preclusion. A party is barred from relitigating an issue where it (1) is identical to one decided previously, (2) was actually litigated, (3) was necessary to the prior judgment, and (4) the party had a full and fair opportunity to litigate it. Even when these elements are met, courts retain discretion in light of fairness and judicial efficiency.

The court held that the core issues adjudicated in the Virginia bench trial overlap directly with those in this MDL. Both actions concern Google’s conduct across the publisher ad server, ad exchange, and related ad-buying technologies, and the plaintiffs in both cases allege that Google used its vertical control to exclude rivals and maintain monopoly power. However, specific market-definition questions in this MDL are broader than those adjudicated in Virginia, and therefore, not all issues are identical. The court thus undertook a finding-by-finding comparison, applying preclusion only when the factual determinations are similar.

The court held that Google is precluded from contesting findings that (1) Google possessed monopoly power in core digital advertising markets (including the publisher ad server and ad exchange), and (2) Google maintained that power through exclusionary conduct, including self-preferencing, tying, and agreements that impeded rivals. The court also precluded relitigation of findings that Google manipulated internal auction mechanics to favor its own products.

The court declined to preclude disputes over: (1) market definitions that are broader or differently framed in this MDL, (2) class-wide impact and damages, which were not adjudicated in Virginia, and (3) conduct occurring after the close of the Virginia trial record.

Rejection of Google’s fairness arguments. The court rejected Google’s arguments that preclusion was improper because the Virginia judgment is on appeal, noting that a judgment is final for preclusion purposes unless stayed. It also found that Google had a full and fair opportunity to litigate in Virginia and cannot “re-try” issues here merely because it was dissatisfied with the prior outcome.

Conclusion. Google was precluded from relitigating the following findings from the Eastern District of Virginia bench trial, including the balancing of procompetitive justifications and anticompetitive effects (a) that publisher ad servers and ad exchanges constitute separate and distinct markets; (b) that these markets are worldwide in scope, excluding jurisdictions with restricted internet access or U.S. sanctions; (c) that Google engaged in anticompetitive conduct to willfully acquire and maintain monopoly power in these markets, including Unlawful Tying, First Look, Last Look, Dynamic Revenue Share, and Unified Pricing Rules; and (d) that Google unlawfully tied DoubleClick for Publishers and AdX in violation of Section 1 of the Sherman Act.

The Case is No. 1:21-cv-03446-PKC.

Judge: Castel, P.

Attorneys: John Thorne (Figel & Frederick, P.L.L.C.) for Associated Newspapers Ltd. Caroline Boisvert (Axinn Veltrop & Harkrider, LLP) for Google LLC.

Companies: Associated Newspapers Ltd.; Google LLC

Cases: TechnologyInternet NewYorkNews