Ann O'Brien

Ann O'Brien advises corporations and individuals facing criminal and civil antitrust investigations and litigation. A former antitrust prosecutor and leader at the U.S. Department of Justice for nearly 20 years, Ann brings her experience and valuable agency insights to her clients. Ann is co-leader of the Antitrust and Competition practice group.

During her government service, Ann was involved in virtually every major criminal enforcement and policy decision made by DOJ’s Antitrust Division. In private practice, Ann has successfully defended clients in novel and high-stakes antitrust investigations and litigation, including some of the nation’s first antitrust no-poach, criminal monopolization and AI facilitated collusion matters. She also has comprehensive knowledge of antitrust enforcement in other countries and has developed strong relationships with both U.S. and foreign antitrust enforcers and regulators.

Recognized by Chambers USA for antitrust and cartels, Ann uses her experience to strategically guide clients facing international, domestic and multi-agency antitrust and competition exposure and parallel litigation as few lawyers can.

Clients appreciate Ann’s responsive, solution-oriented approach, bringing a strategic focus to antitrust investigations and litigation and identifying key issues early in order to open pathways to resolution.

Ann has substantial experience leading every aspect of domestic and international antitrust and white-collar investigations and prosecutions, including litigating federal criminal jury trials.

She also provides clients with cutting-edge compliance counseling and training that can help deter or quickly detect antitrust exposure, informed by what is most important to the DOJ, FTC, and the courts.