Patricia McMahon

Senior Associate
Toronto: 416.865.7690
Fax 416.865.7380


JSD, 2015
Yale Law School
LLM, 2004
Yale Law School
LLB (Honours), 2002
University of Toronto
PhD (History), 1999
University of Toronto

Bar Admissions

Ontario, 2004


Patricia (Trish) is a research lawyer in the Torys’ Litigation and Dispute Resolution Practice. She has extensive experience in class action proceedings, tax disputes, constitutional law, administrative law and public law, having appeared before all levels of court. She is a member of the firm’s appellate practice group.

Representative Work

Load More



Professional Involvement

Before joining Torys, Trish was a litigation associate at a law firm in Toronto. Previously, Trish clerked for Mr. Justice Ian Binnie at the Supreme Court of Canada. Trish was a Fulbright Scholar and a Lillian Goldman Scholar at Yale Law School, where she served as a student director in a legal aid clinic dedicated to civil liberties litigation related to the policies of the U.S. government following the attacks of September 11th, working on cases involving detentions, search and seizure, due process, international human rights and humanitarian law.

Trish’s graduate work in law focused on the fusion of law and equity and the roots of modern civil procedure. She has been invited to address legal symposia at the University of Cambridge and Harvard Law School. She has published two books, Essence of Indecision (2009), a study of John Diefenbaker’s nuclear policy, and The Person’s Case (2007, with Mr. Justice Robert Sharpe), a history of the legal and political fight by Canadian women to serve in the Senate of Canada. She was co-editor-in-chief of the University of Toronto Faculty of Law Review and received the Dean's Key for "excellence in extra-curricular work of an academic nature."

Trish is the coordinator of the Oral History Program at the Osgoode Society, an organization that promotes and preserves Canada’s legal history. Since its inception in 1979, the Society has published more than 100 books and conducted more than 600 oral history interviews of leading members of the legal profession.


Trish served as a regional representative for the Executive Committee of Yale Law School from 2004 to 2008.