Mark A. Mason

AVP, Senior Practice Counsel

4800 – 100 King Street West
Toronto, Ontario, M5X 2A2

Bar Admissions

  • Ontario, 1997


  • B.A. (Hons.) York University (1990)
  • M.A., York University (1992)
  • LL.B., Osgoode Hall Law School (1995)

Professional Accreditations and Affiliations

  • Canadian Bar Association
  • Ontario Bar Association
  • Toronto Lawyers Association
  • The Advocates Society

About Lawyer

Mark Mason is Senior Practice Counsel at the Toronto office, having joined Aviva Trial Lawyers in 2023. Prior to this, Mark was a founding partner of a Toronto litigation boutique specializing in subrogation. He is a well-recognized and seasoned subrogation lawyer who has practiced subrogation almost exclusively for the past 25+ years.

Mark has trial, appellate, arbitration, and mediation experience, and has acted as counsel in matters before all levels of court in Ontario, the Supreme Court of Canada, and various administrative bodies and regulatory tribunals. He has acted as counsel and has provided guidance and mentorship to other lawyers on some of the most important subrogation court cases in Canada.

Mark has written extensively and spoken widely on subrogation and related topics.

Between 2010 and 2020, Mark was Chair of the Canadian Chapter of the National Association of Subrogation Professionals (NASP).

Mark was called to the Ontario Bar in 1997. He graduated from Osgoode Hall Law School in 1995, after having received undergraduate and graduate degrees from York University.  In 2019, Mark received a diploma in Alternative Dispute Resolution from the University of Windsor. 

Personal Interests

Mark is an avid golfer, long-distance runner and loves to travel.