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Eric Mahr

Joint Head – Global Antitrust Litigation Group

Antitrust and competition | Commercial litigation | Investigations |

A first-rate trial lawyer with superb courtroom presence [...] Eric is an excellent overall litigator.

Chambers USA 2022

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About Eric Mahr

Eric is an antitrust and litigation partner in our Washington, DC office, and co-chair of the firm’s global antitrust litigation group. He serves on the Firm's global Board.

Eric specializes in US antitrust litigation. For the past 20 years, he has represented clients in complex, high-stakes cases at trial and on appeal in federal district and appellate courts throughout the United States. He has defended clients in civil and criminal investigations, enforcement actions, and other regulatory proceedings both in the United States – before the US Department of Justice (DOJ) and the Federal Trade Commission (FTC) – and in Europe, before the European Commission and numerous national competition authorities.

Eric is one of a small number of antitrust litigators in the country to have actually taken antitrust cases to trial, and one of even fewer to have won those cases at trial both for defendants in private practice and as a prosecutor for the US Department of Justice.

Eric was lead trial counsel in FTC v. RAG Stiftung, et al, in which Freshfields defeated the FTC’s attempt to block our client Evonik’s proposed acquisition of PeroxyChem in the North American hydrogen peroxide marketplace. Our trial victory marked the FTC’s first loss in a litigated merger challenge since 2015 and only the second time in the last 20 years that the Commission chose not to challenge a trial loss on appeal.

Prior to joining Freshfields, Eric served as the Director of Litigation for the DOJ's Antitrust Division from 2015 through 2017. In that role, he oversaw the Division's antitrust enforcement actions, with a focus on civil litigation and trials. The Division filed more than 10 contested cases during his tenure and prepared for litigation in many more. Of the cases filed, the Division tried three to final judgment and won them all (US v. Aetna/Humana, US v. Anthem/Cigna and US v. EnergySolutions/WCS). 

In 2017, Eric was honored with the Attorney General’s Distinguished Service Award for the Aetna/Humana trial victory, and in 2016 received the Assistant Attorney General’s Award of Distinction for serving as lead counsel in US v. United Continental/Delta (the Newark Slots matter). 

In addition to his litigation work, Eric helps guide clients through antitrust investigations and second phase merger proceedings on both sides of the Atlantic, particularly where there is a significant potential for the relevant agency to challenge the transaction at issue.

Before his appointment as Director of Litigation, Eric spent 12 years as a partner in WilmerHale's Washington, DC office, and four years in that firm's Brussels office, where he practiced before the European Commission and various national competition authorities. He began his career as a trial attorney in the DOJ, Civil Division, Federal Programs Branch, after clerking for the Honorable Raymond J. Broderick of the US District Court for the Eastern District of Pennsylvania.


Recent work

  • Lead counsel representing Google in The State of Texas, et al. v. Google, LLC (ED Texas), United States v. Google LLC (EDVA), and in the MDL In re Google Advertising Antitrust Litigation (SDNY), in its defense of litigation brought by the US DOJ, Texas AG, and 33 other state AGs, as well as various class action plaintiffs, alleging violations of Sections 1 and 2 of the Sherman Act in connection with Google’s ad tech business.
  • Lead counsel defeating the FTC at trial in that agency’s challenge to Evonik’s proposed acquisition of PeroxyChem, a competing hydrogen peroxide producer. This victory ended the FTC’s seven-trial win streak in litigated merger challenges and marked only the second time the FTC has been defeated at trial since 2011 (DDC).
  • Lead counsel for Norwegian farm-raised salmon producer in multidistrict US class action litigation alleging price-fixing of farm-raised Atlantic salmon sold into the United States (SD Fla, D Me).
  • Assisted Change Healthcare and its lead counsel with trial preparation in Change Healthcare's successful defense of the US DOJ's challenge to its acquisition by UnitedHealthcare in United States v. UnitedHealthcare Group Inc. (DDC).
  • Successfully defended leading multinational chemicals company in a putative class action lawsuit alleging that competing diisocyanate producers reduced output through coordinated, pretextual facility shutdowns and increased prices through coordinated price increase announcements (WD Pa).
  • Lead counsel for Lufthansa, Lufthansa Cargo, and Swiss International Air Lines in the In re Air Cargo Shipping Services Antitrust Litigation, which included more than 90 class actions alleging worldwide conspiracy to fix fuel and security surcharges on air cargo flights (EDNY).
  • Represented innovator pharmaceutical company Cephalon against FTC and private plaintiff “reverse payment” actions under FTC Act § 5 and Sherman Act seeking over $5 billion in disgorgement and damages (DDC, ED Pa).
  • Successfully defended Intel against FTC enforcement action under Section 5 of the FTC Act (FTC Part III administrative adjudication).
  • Successfully represented Braintree Laboratories at trial in patent infringement action, where competitor asserted antitrust counterclaims for unfair competition and violation of the Sherman Act § 2 under Professional Real Estate Investors “sham” litigation exception to Noerr–Pennington immunity (D Del).
  • Successfully represented a broad range of other US and international clients in merger investigations, criminal grand jury investigations, and complex civil litigation and arbitration in the United States, Europe and around the world, including International Paper, Dean Foods, Andritz AG, Grieg Seafood, Outokumpu Oy, Washington Gas, Salt River Project, Schaeffler AG and Distrigas NV.



  • JD, magna cum laude, University of Pittsburgh School of Law.

  • BA, Bucknell University


  • Admitted to practice in the District of Columbia and Pennsylvania.
  • Admitted to the U.S. Supreme Court and numerous U.S. federal circuit and district courts across the United States.
  • Admitted to L'Ordre Francais des Avocats du Barreau de Bruxelles (2000-2004).
  • Director of Litigation for the Antitrust Division of the U.S. Department of Justice (2015-2017).
  • Private Practice in Washington, D.C. and Brussels, Belgium (1997-2015).
  • Trial attorney in the Federal Programs Branch of the Civil Division of the U.S. Department of Justice (1992-1997).
  • Law clerk to the Honorable Raymond J. Broderick of the U.S. District Court for the Eastern District of Pennsylvania (1990-1992).

Awards and recognition

  • In 2023 and years previous, recognized as a leading antitrust litigator in the United States and Washington, D.C., by Chambers, Best Lawyers, Who’s Who Legal, Legal 500, Super Lawyers, and several other rating/ranking agencies.
  • In 2022, recognized in Lawdragon 500 Leading Litigators in America – Antitrust Litigation & Investigations
  • In 2020, chosen as one of the National Law Journal's Masters of the Courtroom: Winning Litigators 2020
  • In 2020, named by Global Competition Review as “Litigator of the week” and as a finalist for “Litigator of the Year” for his work as lead trial counsel to Evonik in its acquisition of PeroxyChem.
  • In 2017, awarded the U.S. Attorney General’s Award for Distinguished Service from the U.S. Department of Justice.
  • In 2016, awarded Assistant Attorney General’s Award of Distinction from the Assistant Attorney General, Antitrust Division.

Speaking Engagements 

  • The Failing Firm Defense under U.S. Law, Presenter, Quadrilateral Meetings among U.S., Mexican, and Canadian Antitrust Enforcers, Washington, D.C. (October 2017)
  • The Public/Private Partnership in Antitrust Enforcement, Speaker, American Antitrust Institute18th Annual Conference: The Value of Antitrust, National Press Club, Washington, D.C. (June 21, 2017)
  • Representing Non-Party Witnesses in Merger Investigations and Litigation, Speaker, ABA Section of Antitrust Law, Spring Meeting 2017, Washington, D.C. (March 30, 2017)
  • Agency Update with the U.S. Department of Justice, Speaker, ABA Section of Antitrust Law, Spring Meeting 2017, Washington, D.C. (March 29, 2017)
  • Competition Litigation Around the World, Chapter One: The United States, Speaker, ABA Teleconference, ABA International Committee and the Civil Practice and Procedure Committee, Washington, D.C. (May 29, 2014)
  • Civil Litigation in the Aftermath of Criminal Litigation, Speaker, ABA Section of Antitrust Law, 2014 Spring Meeting, Washington, D.C. (March 26, 2014)