Professional Biography

Brien McMahon Partner

  • San Francisco

    D +1.415.344.7165

    F +1.415.344.7365

    San Francisco

    505 Howard Street, Suite 1000

    San Francisco, CA




Brien McMahon has more than 40 years of product liability, commercial, real estate and environmental litigation experience. For the last 14 years, Brien has been a member of the firm’s asbestos litigation team. He has coordinated malignancy case assignments, supervised day-to-day case management activities (discovery, fact investigation, expert witnesses and trial preparation) and tried cases. Brien also has experience in environmental litigation matters, particularly in relation to winery development projects, alleged groundwater contamination and toxic tort issues.

Throughout the course of his career, Brien has represented some of the country’s largest companies in asbestos and product liability litigation. In the 1980s, Brien represented National Gypsum, in the early 1990s, The Boeing Company and W.R. Grace & Company and in the 2000s, Honeywell International Inc., Georgia-Pacific, LLC, The Boeing Company, Lucent Technologies and Lamons Gasket in asbestos-related actions. Brien is a member of Honeywell’s national trial team and has been selected as trial counsel in over 20 asbestos matters. Brien has selected juries in numerous cases; favorably resolved numerous cases during or after jury proceedings; and has tried three cases to jury verdict since 2013, including a defense verdict in a female mesothelioma case where the client’s product was the only identified exposure. In other jury trials, where his client was principal target and sole trial defendant, the award was less than 10% of amounts sought.

Brien has also represented the Ford Motor Company in a product liability action arising from a vehicle rollover, The Boeing Company in a product liability action arising from an alleged defectively designed aircraft elevator system, and Triquint Semiconductor Inc. in an action alleging birth defects from alleged workplace exposure to toxic chemicals. Brien is a former partner of Johnsen Manfredi & Thorpe and following its merger with Perkins Coie in 1988, was of counsel in the Los Angeles office from 1988-1993 before becoming a partner.

Professional Leadership

  • North Bay World Trade Association, Former Director, 1996 - 1999; President, 1999
  • World Affairs Council of Sonoma County, Founding Director
  • Sonoma County International Forum, Chairman, 1997
  • National Association of Securities Dealers Arbitrator

Related Employment

  • White McMahon Potter, Santa Rosa, CA, Partner, 1985 - 2005
  • Perkins Coie LLP, Los Angeles, CA, Of Counsel, 1988 - 1993
  • Johnsen, Manfredi & Thorpe, Los Angeles, CA, Associate and Partner and Of Counsel, 1975 - 1988





Areas of Focus

Bar and Court Admissions

  • California

  • U.S. Court of Appeals for the Ninth Circuit

  • U.S. District Court for the Northern District of California

  • U.S. District Court for the Central District of California

  • U.S. District Court for the Eastern District of California

  • U.S. District Court for the Southern District of California


  • The University of Southern California, J.D., 1975,
    Note and Article Editor, Southern California Law Review
  • Tufts University, M.B.A., The Fletcher School of Law and Diplomacy, International Affairs, 1980
  • The University of Pennsylvania, B.A., 1970