Kathleen J. McMahon

  • Biography
  • Key Cases

Kathleen J. McMahon specializes in antitrust and class action litigation. She approaches her practice with a passionate attitude while providing her clients with high-quality legal representation. 

Kathleen has extensive success in antitrust class actions and other areas of law, including tax law with an emphasis in state and local tax compliance, property law, corporate law, personal injury, and criminal defense. She has substantially contributed in all case stages, including case development; factual investigation and drafting of pleadings; discovery; taking and defending depositions; researching, drafting, and orally arguing motions in federal and state court; and arbitration and trial preparation.

Kathleen has played and continues to play a key role in the Microsoft Acquisition of Activision Litigation by assisting in the drafting of pleadings, motions, discovery, and orally arguing motions in court. She also represents content moderators and consumers, respectively, in TikTok Content Moderators' Safe Workplace Litigation and Nestlé Bottled Water Litigation.

Previously, Kathleen was an associate at Berding Weil, LLP, where she represented Homeowners Associations and individuals in construction defect lawsuits. She also worked with partners in advising clients in a general counsel capacity. Before that, she was an associate at Andersen Tax, LLC in the State and Local Tax (SALT) group, where she worked on projects related to changing high net worth clients’ residences, performed nexus studies, and represented clients with “controversy” matters before the Franchise Tax Board, Office of Tax Appeals, and Internal Revenue Service.

While in law school, Kathleen clerked at a plaintiffs-side class action law firm and interned at a criminal defense law firm. She was also an intern for Andersen Tax, LLC in the Private Client Services line, prior to accepting a post-bar associate position in the SALT group. In law school, she was part of the Women’s Law Association and Pilipino American Law Society. She works on various civil rights cases.