Mary was admitted to the Alberta bar in 1990.  For 27 years she focused on commercial litigation and arbitration at Macleod Dixon (now Norton Rose Fulbright), retiring from the firm on December 31, 2017 as Senior Partner and Chair of the Litigation Practice Group in Calgary.  She has been broadly recognized as a leading lawyer in dispute resolution, particularly in the energy area.

Mary has enjoyed the transition from advocate to adjudicator and has sat as sole arbitrator and on Tribunals, including as Chair.  Mary is appointed to the rosters of a number of institutions including ICDR Canada and the Vancouver International Arbitration Centre Domestic and International Panels.