William A. Hanssen



William Hanssen defends clients in the pharmaceutical and medical device industries, protecting their innovations during product liability litigation, mass torts and consumer class actions. He serves as both national coordinating counsel and local counsel in mass tort litigation, developing and executing effective strategies. Bill has defeated motions for class certification in consumer class actions and is also experienced in commercial litigation.

Product Liability and Mass Tort Litigation

Bill defends product liability cases involving over-the-counter medications, food products, pesticides, pediculicides, hospital equipment and industrial equipment. He has been involved in mass tort litigation over TMJ implants, breast and hip implants, cold remedy products, antidepressants and antipsychotics. In addition to serving as trial or coordinating counsel, Bill prepares expert witnesses and coordinates factual discovery.

Consumer Class Actions

Bill has successfully defended companies against claims of false advertising, unfair business practices and unfair competition — including helping a major pharmaceutical manufacturer win at trial in a case alleging violations of the California Unfair Business Practices Act. He defends consumer class actions involving weight loss products, pain relievers, dietary supplements and homeopathic cold remedy products.

Commercial Litigation

Beyond his product work, Bill has represented companies in contract and licensing disputes involving intellectual property and insurance carriers in insurance coverage litigation. He has defended companies in employment litigation alleging wrongful termination and discrimination.


Bar Admissions


Court Admissions

U.S. Court of Appeals for the Ninth Circuit
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 Northern District of California
U.S. District Court for the Southern District of California


University of San Diego School of Law
J.D. (1983)

University of California, Santa Barbara
B.A. summa cum laude (1978)

Insights & Events

Leadership & Community

Professional Associations

  • California Bar Association
  • Defense Research Institute — Drug & Device Section
  • Los Angeles County Bar Association
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