Matt O’Donnell is an Antitrust & Competition associate in Mayer Brown’s Chicago office. His practice focuses on representation of clients through all stages of restraint of trade litigation, including pleadings, motion practice, written discovery, and preparation of economic experts. Matt also assists in advising companies on merger analysis and clearance. He actively represents clients in the chemicals, consumer packaged goods, agricultural, and financial services and insurance industries.

Matt also has substantial experience representing clients in ERISA, products liability, immigration, and complex commercial and class action matters. His experience spans both the federal and state court systems and includes multi-district litigation matters.

On the pro bono side, Matt has a keen interest and experience in immigration law matters, where he represents clients from Mexico and Afghanistan who are seeking asylum. During law school, he served as a research assistant to Professor Hiroshi Motomura, the faculty co-director of the UCLA School of Law Center for Immigration Law and Policy. Matt was also a student attorney at the University of Michigan Law School Innocence Clinic, where he assessed applications, investigated claims, interviewed witnesses, and assisted in drafting habeas petitions.


  • Representing a multinational corporation and North American subsidiary in multidistrict litigation alleging conspiracy and antitrust violations against global manufacturers of polyurethane chemicals.
  • Representing a global corporation in complex antitrust litigation alleging conspiracy and antitrust violations against manufacturers of consumer packaged goods.
  • Representing a North American subsidiary of an international corporation in civil litigation alleging RICO and negligence against parties providing bonding to construction companies for government set-aside procurements.
  • Representing a bank in class action litigation alleging breach of contract for charging certain fees.
  • Representing a multinational corporation and North American subsidiary in class action ERISA litigation alleging breach of fiduciary duty and prohibited transactions against a retirement plan provider.


UCLA School of Law, JD

University of Michigan, BA


  • Illinois


  • US Court of Appeals for the Seventh Circuit
  • US Court of Appeals for the Ninth Circuit
  • US District Court for the Northern District of Illinois
  • US EOIR Immigration Court & Board of Immigration Appeals


  • Co-Chair of Mayer Brown Chicago Committee of Associates, 2021-Present
  • Board Member, National Immigrant Justice Center’s Associate Leadership Board, 2021-Present
  • American Bar Association, Antitrust Section, 2021-Present