Maggy Sullivan, a nationally recognized trial lawyer, represents multinational clients in complex antitrust litigation and investigations before federal regulators. She ranks among an elite few antitrust trial lawyers who have secured multiple merger litigation victories against the government.

Ms. Sullivan brings strategic foresight and more than two decades of experience to her work managing litigation in all its forms, including:

  • Investigations
  • Complex civil actions
  • Multi-district actions
  • Class actions

She regularly develops compelling theories and strategies and excels at persuading parties across the litigation spectrum to adopt her perspective. Ms. Sullivan has won two of the most complex, high-profile matters in the history of the US Department of Justice (DOJ): the Illumina/GRAIL merger and the Booz Allen Hamilton/EverWatch merger.

Her established track record demonstrates excellence in handling sprawling, long-running antitrust matters that run the gamut from investigation, to criminal prosecution, to multi-district litigation, or commercial class actions.

Ms. Sullivan is regularly recognized for her work by leading industry publications, including Chambers USA, Global Competition Review, Legal 500, and Benchmark Litigation.

Ms. Sullivan’s successes include representing:

  • Illumina; defeating the US Federal Trade Commission (FTC) in its lawsuit challenging Illumina’s acquisition of GRAIL, a manufacturer of early cancer detection tests; the only time the FTC has been defeated in its own administrative court
  • Booz Allen Hamilton, defeating the DOJ in its attempt to block Booz Allen Hamilton’s acquisition of defense contractor, EverWatch
  • A tech company in the automotive recovery space in a sprawling and multi-forum litigation related to damage estimates
  • Sumida Corporation in a multi-faceted class action alleging price fixing among certain Japanese inductor manufacturers; after Latham secured an initial motion to dismiss, an opt-out plaintiff filed an amended complaint, for which Latham was able to obtain a dismissal with prejudice, despite an active DOJ investigation
  • 10x Genomics in antitrust claims in an ongoing patent suit brought by a rival
  • A leading airline industry client in a private class action litigation related to its agreement with other airlines
  • A major industrial client; achieved amnesty in multiple jurisdictions around the world
  • A Hong Kong-based technology company; obtained the first-ever global resolution of criminal and civil claims (including antitrust and False Claims Act claims) asserted by the US government on favorable terms and in record time
  • A natural gas and energy supplier; obtained dismissal of monopolization claims based on the Filed Rate Doctrine and lack of antitrust standing
  • A table saw manufacturer; obtained dismissal of boycott claims based on insufficient allegations of conspiracy
  • A Japanese auto parts supplier; obtained dismissal of price fixing claims on jurisdictional grounds

Bar Qualification

  • District of Columbia
  • Virginia


  • JD, Northwestern University School of Law, 2000
  • BA, Bowdoin College, 1995