Mark S. Popofsky, a veteran of the landmark Microsoft trial, heads Ropes & Gray’s antitrust practice. A first-chair trial lawyer, Mark litigates antitrust, intellectual property and other complex business litigation matters. Mark’s litigation practice includes jury trials, class actions (including cartel cases), arbitrations and appeals throughout the federal and states courts.

Mark regularly counsels Fortune 500 companies on the full-range of antitrust matters across numerous industries, including high technology, telecommunications, medical device, pharmaceuticals, aerospace, manufacturing, health care and consumer products. With deep and recognized experience in the intersection of intellectual property and antitrust, Mark advises leading Internet, semiconductor, hardware, software and telecommunications clients on business practices, competitor collaborations and distribution arrangements. He also represents parties in civil and criminal antitrust investigations and transactions before the U.S. Department of Justice and the Federal Trade Commission.

Mark served in the late 1990s as Senior Counsel to Assistant Attorney General Joel Klein in the U.S. Department of Justice’s Antitrust Division, where he played a key role in United States v. Microsoft Corp. Mark previously served in the Division’s Appellate Section, where he argued the landmark victory in United States v. Nippon Paper – which established the extraterritorial application of U.S. antitrust law in cartel cases – and as a Special Assistant U.S. Attorney in Alexandria, Virginia (the “Rocket Docket”), where he tried numerous jury cases to verdict. Following government service, Mark in 1999 was named the youngest partner in the history of a renowned international law firm and served as Chair of its Technology and Competition Group.

Recently, Mark has served as litigation counsel for Google in United States v. Google, the Government’s monopolization suit, and achieved a landmark victory for Biogen in the California Supreme Court in Ixchel Pharma, LLC v. Biogen, Inc., 9 Cal. 5th 1130 (2020), a case at the intersection of antitrust, non-compete, and tortious interference law. This victory garnered Mark LMG Life Science’s Antitrust Litigator of the Year award, as well as recognition in 2021 for Impact Case of the Year US Non-IP Litigation. Mark also has represented major telecommunications firms in transactions before the U.S. Department of Justice and in government litigation. In cases raising antitrust counterclaims in intellectual property disputes, Mark has achieved notable motion to dismiss wins.

Mark is an Adjunct Professor of Advanced Antitrust Law and Economics at the Harvard Law School and the Georgetown University Law Center; he has taught Advanced Antitrust law since 2000. He writes and speaks frequently on antitrust law and policy and has been interviewed by The Wall Street Journal, Bloomberg, Global Competition Review and Law360. His Article on the Sherman Act’s Criminal Extraterritoriality won the 2012 Burton Award for Legal Achievement. Mark is a long-time leader in the ABA Section of Antitrust law. Mark also serves as a member of the BNA Antitrust Advisory Board.

Mark is sought for his antitrust experience by The Wall Street Journal, The Washington Post, The Los Angeles Times, NBC News, and BBC America.


Representative Matters

  • Google. Litigation Counsel for Google in the United States v. Google (D.D.C.) monopolization suit. The United States v. Google litigation earned Ropes & Gray recognition for ‘Behavioral Matter of the Year’ in 2022 by Global Competition Review.
  • Major pharmaceutical manufacturer. Lead attorney for Biogen in Ixchel Pharma, LLC v. Biogen, Inc., 9 Cal. 5th 1130 (2020), the landmark California Supreme Court decision establishing the contours of California non-compete, antitrust, and tortious interference law following two successful motions to dismiss, ultimately affirmed by the U.S. Court of Appeal for the Ninth Circuit. In recognition of Mark’s role in this landmark case, among other matters, he was named 2020 LMG Life Sciences Antitrust Litigator of the Year and the firm was awarded Impact Case of the Year US Non-IP Litigation at the 2021 awards.
  • Major medical device manufacturer. Lead attorney in securing dismissal of three attempted antitrust counterclaims alleging tying, refusals to deal, and other acts of asserted monopolization in trade secret/copyright litigation (N.D. Cal.).
  • Major hospital system. Represented major hospital system in DOJ investigation of alleged anti-steering restrictions. The DOJ closed the matter without an enforcement action.
  • Major technology manufacturer. Represents major technology manufacturer in EC investigation of non-solicitation agreement.
  • Charter Communications. Represented Charter Communications in connection with the United States v. AT&T/Time Warner litigation and other transactions.
  • Cablevision. Lead litigation counsel for Cablevision in asserting claims against Viacom for illegally tying programming networks (S.D.N.Y). Also lead litigation counsel for Cablevision in putative class action alleging monopolization and related claims involving cable set-top boxes (D.N.J.).
  • Google. Counsel to Google in connection with patent practices, in government antitrust investigations, and in securing clearance from the Antitrust Division of Google’s $2.35 billion sale of Motorola Home to Arris.
  • Questcor Pharmaceuticals. Lead litigation counsel for Questcor in defending monopolization suit brought by putative competitor (C.D. Cal.).
  • Hitachi-LG Data Storage. Co-lead litigation counsel for Korean-Japanese joint venture in defending putative civil class actions and related cases alleging price-fixing in the optical disk drive industry (N.D. Cal.).
  • Taitsu Corporation. Co-lead litigation counsel for Japanese components manufacturer and its U.S. subsidiary in defending putative class actions in the capacitors industry brought by direct and indirect purchasers (N.D. Cal.).
  • Illinois Tool Works. Co-lead litigation counsel in securing dismissal of antitrust claims alleging a conspiracy to manipulate standards setting to exclude a rival (D. Mass).
  • Leading Academic Institutions. Lead antitrust counsel in matters relating to athletics programs, government investigations, and joint ventures with sister institutions.
  • Auto Parts. Counsel to Japanese auto parts supplier in defending against price-fixing claims brought by customers.
  • Lead antitrust counsel in successfully defending hospital against monopolization claims (N.D. Cal.).
  • Lead antitrust litigation counsel for major pharmaceutical company in successfully sustaining monopolization claims against rival in patent/antitrust litigation; also litigated eBay issues in remedy phase of patent trial (D. Mass.).
  • Lead antitrust counsel for Korean ATM manufacturer in asserting unfair competition claims against rival (N.D. Cal.).
  • Secured favorable plaintiff-side settlement of trade secret litigation in optical networking industry.
  • Secured clearance from the Antitrust Division of leading aerospace manufacturer’s acquisition of rival’s wheel and brakes business.

Areas of Practice