Matthew O’Brien is a member of Polsinelli’s Litigation Department and an experienced litigator who works with and advocates on behalf of clients through the entire litigation process. He focuses his practice on commercial and products liability and toxic and mass tort matters, including representing clients in matters involving asbestos, benzene, beryllium, groundwater contamination, medical equipment, perchloroethylene, petroleum, solvents, talc and tractors.

Matthew understands that no two clients or cases are the same and works with clients to develop and successfully implement individualized litigation plans and strategies. He has experience working as both national coordinating and local counsel. At his prior firm, Matthew served as national coordinating counsel for a Fortune 100 company, developing and implementing case and discovery strategies across numerous jurisdictions. He has served as local counsel for numerous companies and organizations in California federal and state courts. Matthew has prepared and defended multiple corporate witnesses for deposition in personal injury and wrongful death lawsuits. He also led in the development of systems for a governmental agency’s e-discovery efforts in connection with mass licensing denial appeals litigation.

Matthew is also an active member of Polsinelli’s motion practice team. He has successfully briefed and argued numerous types of motions at both the state and federal levels, including demurrers/motions to dismiss, motions for summary adjudication and motions for summary judgment. Matthew’s motion practice has resulted in obtaining dismissals or judgment in his client’s favor and eliminating causes of action and punitive damages claims. He also contributed to briefing efforts in a habeas corpus petition and, separately, argued before the Ninth Circuit Court of Appeals, resulting in a published decision in his client’s favor.

With a commitment to provide sound legal advice, Matthew works closely with Polsinelli attorneys to successfully defend complex product liability and high-risk toxic tort matters. He leverages his prior experience serving as an extern for the Los Angeles Superior Court and an intern for the U.S. House of Representatives in Washington, D.C.

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Education

  • Pepperdine Caruso School of Law (J.D., 2015)
    • cum laude
  • Georgetown University (M.A., 2013)
    • University of Wisconsin-Madison (B.A., 2009)

      Bar Admission

      • California

      Court Admissions

      • U.S. District Court, Central District of California
      • U.S. District Court, Northern District of California
      • U.S. District Court, Eastern District of California
      • U.S. District Court, Southern District of California

      Professional Affiliations

      • California Lawyers Association
        • Litigation Section Executive Committee Member, 2022-present
      • State Bar of California
      • American Bar Association
      • Los Angeles County Bar Association
      • LGBT Bar Association of Los Angeles
      • University of Wisconsin Alumni Association

      Recognition

      • Participant, Polsinelli Trial Academy facilitated by NITA, 2025
      • Named one of Best Lawyers: Ones to Watch® in America in Product Liability Litigation - Defendants, 2024-2026