O’Melveny Worldwide

Kelse Moen is a counsel in the firm’s Antitrust and Competition Practice Group, where he represents clients in a broad range of matters, including complex commercial and class action litigation, criminal cartel defense, and regulatory investigations. He is an experienced litigator who has assisted clients at every stage of litigation, through briefing dispositive motions, deposing adverse parties and expert witnesses, and arguing in court. Recently, he was a key part of the trial team that won the jury acquittal of an executive who the Department of Justice prosecuted across an unprecedented three criminal trials in federal court.

Prior to joining O’Melveny, Kelse worked as an associate in the antitrust group of another major law firm. Before that, he served as a law clerk to Judge Robert D. Mariani of the United States District Court for the Middle District of Pennsylvania.

  • Defending an executive charged with price fixing in three criminal trials against the Department of Justice in federal court, ultimately resulting in a complete acquittal
  • Winning regulatory clearance for a merger of technology companies from the Federal Trade Commission
  • Defending a solar energy company against consumer class action allegations in federal court
  • Representing healthcare clients in federal investigations and qui tam actions
  • Defending a large automobile manufacturer in an antitrust class action, achieving a favorable settlement on the eve of trial


Bar Admissions

  • District of Columbia
  • Massachusetts


  • Cornell University, J.D.
  • Emory University, B.A., Philosophy/Political Science

Professional Activities


  • The Honorable Robert D. Mariani, US District Court, Middle District of Pennsylvania



  • “Why Economics Matters in Criminal Antitrust Cases,” Kelse Moen, Anna Pletcher and John Gonzalez, Antitrust Magazine Volume 37, Issue 2 (March 21, 2023)


  • Panelist, “Recent Developments in Antitrust Law,” Western Alliance Bank Class Action Law Forum Virtual Conference with University of San Diego School of Law (April 21, 2021)