Maggy Sullivan is a partner in the Litigation & Trial Department of Latham & Watkins and is a member of the firm’s Antitrust & Competition Practice. She is a former member of the firm’s Finance Committee and Strategic Client Committee. She has extensive experience in both private and government antitrust matters and has defended corporate clients in litigation against the Department of Justice (DOJ) and Federal Trade Commission (FTC), cartel investigations, complex civil actions, multi-district actions, and class actions.

Ms. Sullivan focuses on antitrust litigation in state and federal courts, criminal cartel investigations, and antitrust compliance counseling. She has been involved in some of the most complex and high-profile antitrust matters to date.

Ms. Sullivan’s antitrust work has covered a wide range of industries, including transportation, defense contracting, energy, consumer products, healthcare, automotive, software and technology, construction materials, specialty chemicals, textiles, medical dictation, paper, cable, and satellite.

Ms. Sullivan has been recognized by numerous publications, including Chambers USA 2022 as a Leading Lawyer in the Antitrust: Litigation Specialist category. Most recently, she was named to Lawdragon 500 2022’s Leading Litigators in America (the inaugural guide), identified as a Benchmark Litigation 2022-2023 Litigation Star and is featured by Who’s Who Legal: Competition 2023 as both a Thought Leader and Global Leader (and has been recognized by the guide for at least the last five years), in addition to many other prestigious accolades.

She was recently recognized as one of American Lawyer’s Litigators of the Week for her work defeating the FTC in a highly watched trial regarding the acquisition of GRAIL, Inc. by Illumina, Inc. Ms. Sullivan also earned an American Lawyer Litigator of the Week Shout Out last year for her victory in defeating class certification on behalf of CCC Intelligent Solutions. In 2017, Ms. Sullivan won Global Competition Review’s award for Cartel Defense Civil Litigation of the Year for her work resolving multiple class action claims against global auto parts suppliers. She is recommended for her cartel defense practice by The Legal 500 US and has been named a Washington, D.C. Super Lawyer several times.

Ms. Sullivan spent two years practicing in Brussels, where she was listed in Chambers 2016 and 2017 as one of the leading antitrust and competition lawyers in Brussels and recognized for her private antitrust litigation expertise and her extensive experience acting before the DOJ. Ms. Sullivan was also named as a Benchmark Litigation 2018 Future Star.

Ms. Sullivan’s successes include:

  • Defeating the FTC in its lawsuit challenging Illumina, Inc.’s acquisition of GRAIL, a manufacturer of early cancer detection tests
  • Defeating the DOJ in its attempt to block Booz Allen Hamilton’s acquisition of defense contractor, EverWatch
  • Obtaining dismissal of class action complaint alleging conspiracy among inductors manufacturers, despite active DOJ investigation
  • Obtaining amnesty for a major industrial client in multiple jurisdictions around the world
  • Obtaining 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
  • Obtaining dismissal of monopolization claims against a natural gas and energy supplier based on the Filed Rate Doctrine and lack of antitrust standing
  • Obtaining dismissal of boycott claims against a table saw manufacturer based on insufficient allegations of conspiracy
  • Obtaining dismissal of price fixing claims against a Japanese auto parts supplier on jurisdictional grounds

Ms. Sullivan currently represents American Airlines in the DOJ’s lawsuit challenging American’s alliance with JetBlue. She also represents a generic pharmaceutical manufacturer in the most complicated multi-district class action litigation ever filed.

Examples of other multi-district class actions include:

  • In re Inductors Antitrust Litigation
  • In re Aftermarket Filters Antitrust Litigation
  • In re Baby Products Antitrust Litigation
  • In re Pressure Sensitive Labelstock Antitrust Litigation
  • In re Polyester Staple Antitrust Litigation

Bar Qualification

  • District of Columbia
  • Virginia


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