William F. Mahoney


Practice Areas


Phone: (312) 645-7806
Email: wmahoney@smsm.com
Website: http://www.smsm.com/
Region: Illinois

Premier 100 Designation for the following years:


Mr. Mahoney is a founding partner of Segal McCambridge Singer & Mahoney and has served as the firm’s Co-Chairman for the past nine years. He has served in a leadership position for all 30 years of the firm’s existence – a period that has seen the firm grow from a four lawyer Chicago firm to over 160 attorneys in seven cities.

Mr. Mahoney is a trial attorney concentrating in the defense of toxic tort and environmental cases. He conducts a national practice and has served as lead counsel at trials in Illinois, Texas, Ohio, Wisconsin, Florida, Kansas, Louisiana, New York, Massachusetts, California and Indiana. He is national trial counsel for defendants named in thousands of asbestos-related cases and has served as national coordinating counsel for several corporations in mass tort litigation. He has been retained as counsel for defendants in state and federal class-action proceedings and participated in the successful dismissal of class-actions involving cellular telephones (brain cancer) and radar guns (leukemia). Mr. Mahoney has substantial experience in electromagnetic field, chemical exposure, mold, benzene, mercury and welding rod litigation. Within the context of his toxic tort practice, he has developed special expertise in epidemiology, medical causation, toxicology, industrial hygiene, risk assessment and biostatistics. Mr. Mahoney also has considerable experience defending general product liability, professional liability, construction, commercial and insurance coverage matters.

In addition to his leadership role at the firm, Mr. Mahoney is active personally and professionally in his community, serving as Board Chairman at two educational institutions, a member of the Chairman’s Circle at the Chicago Council of Global Affairs, a member of the Society of Fellows of the Aspen Institute, a member of the Board of Trustees at Writer’s Theatre, the Chairman’s Council of the National Democratic Institute, and Chairman of the Chicago Committee of Human Rights Watch. He resides in Chicago.


Segal McCambridge Singer & Mahoney, Co-Chairman

Segal McCambridge Singer & Mahoney Executive Committee, Member

Appointed to Federal Asbestos Product Liability Litigation MDL 875 Joint Plaintiff/Defendant Steering Committee, (2006).


  • Recognized as a 2015 Top Rated Lawyer in Mass Torts by American Lawyer Media and Martindale-Hubbell®
  • Selected as a Member of the Nation’s Top One Percent by the National Association of Distinguished Counsel
  • Martindale-Hubbell AV Preeminent® Peer Review Rated
  • Recognized as an Illinois Leading Lawyer (a designation limited to less than 5% of all attorneys licensed to practice law in Illinois), nominated and selected by peers in the legal community (2005-2016)
  • Selected for inclusion in the Illinois Super Lawyers list (no more than 5% of lawyers in the state are selected), nominated and selected by peers in the legal community (2005-2014)
  • Alpha Sigma Nu National Jesuit Honor Fraternity
  • Aspen Institute Executive Leadership Program (2005)
  • Aspen Institute Justice and Law Program (2006)
  • Blue Key Honor Fraternity
  • Recognized as a Top Rated Lawyer in Insurance Law by American Lawyer Media and Martindale-Hubbell®
  • Recognized as a Top Rated Lawyer in Mass Torts by American Lawyer Media and Martindale-Hubbell®
  • Recognized as a Top Rated Lawyer in Energy/Environmental by American Lawyer Media and Martindale-Hubbell®


  • Chairman’s Council – National Democratic Institute
  • Litigation Counsel of America, Fellow
  • Chicago Committee for Human Rights Watch, Chairman
  • Chicago Council on Global Affairs, Chairman’s Circle
  • Aspen Institute, Society of Fellows
  • Writer’s Theatre Board of Trustees, Member
  • Goodman Theatre Business Council, Member
  • Loyola University Foundation, Advisory Board Member
  • Chicago Legal Clinic, Member, Board of Directors (2009-2014)
  • American Bar Foundation, Fellow (2002-present)
  • Chicago Council of Lawyers, Member
  • Defense Research Institute, Member
  • Chicago Bar Foundation “Investing in Justice” Campaign, Vice Chairman
  • Archbishop Quigley Board of Advisers, President (1993-1996)
  • Sacred Heart School Board, President (1994-1997)
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