John Mastoras

Senior Partner
Norton Rose Fulbright Canada LLP

John Mastoras

John Mastoras



John Mastoras is a senior partner in our Canadian employment and labour law group, and acts exclusively for employers. He is known to clients as a passionate and dedicated labour lawyer. He regularly litigates and provides strategic advice in connection with labour arbitrations, labour relations board disputes, collective bargaining negotiations, human rights proceedings, occupational health and safety charges, workplace insurance, labour injunctions and common law employment actions. His practice spans union and non-union workplaces for both federally and provincially regulated employers. 

John is often chief spokesperson in collective bargaining and provides helpful counsel in this regard to a variety of employers. He also routinely acts for a number of employer associations and provides innovative and practical advice to the associations and their members.

John is frequently called upon to litigate highly contentious matters such as disruptive labour disputes and workplace mental health issues in various industries, including energy, pulp and paper, pharmaceutical, health care, insurance, long-shoring, retail, food processing, transportation, steel, building services, technology, automotive and manufacturing more generally.

John has taught for a number of years at the University of Toronto's Centre for Industrial Relations and Human Resources (CIRHR), where he is an adjunct professor. He was conferred the Morley Gunderson Prize by the University of Toronto as a CIRHR graduate who combines outstanding professional achievement with significant service to the university.

Professional experience

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LL.B., Osgoode Hall Law School, 1987
M.I.R., University of Toronto, 1984
B.A.(Hons.), University of Toronto, 1981
  • Ontario 1989
  • Chambers Canada, Ontario: Employment and Labour, Chambers and Partners, 2018-2023
  • Best Lawyers in Canada: Labour and Employment Law, 2015-2024
  • Thomson Reuters Stand-out Lawyers, 2022-2023
  • Canadian Legal Lexpert Directory, 2012-2023: recommended in Workers' Compensation; 2021-2023: recommended in Occupational Health & Safety; 2016, 2019: recommended in Labour Relations - Management 
  • Acritas Stars, 2021 – Named an Acritas Star
  • PLC Which lawyer? 2011 – Labour and Employment
  • University of Toronto, 2009 – Awarded the Morley Gunderson Prize as a CIRHR graduate who combines outstanding professional achievement with significant service to the university
  • "Independent contractors have a duty to mitigate fixed-term damages" (co-author), Norton Rose Fulbright legal update, June 2023.
  • "Workplace Electronic Monitoring" (co-author), HR Policy Association Global Round-up, January 2023.
  • "Workplace Vaccination Policies Evolve" (co-author), HR Policy Association Global Round-up, July 2022.
  • "Top 5 Developments You Should Know About" (co-author), HR Policy Association Global Round-up, April 2022.
  • "Mandatory Vaccination Policy Decisions"(co-author), HR Policy Association Global Round-up, January 2022.
  • "You Can't 'Juke' the Collective Agreement's Exclusive Jurisdiction," Employment and Labour Law Reporter, May 2016 Volume 26, No. 2.
  • "Mexican officials improperly interfered in union representation vote" (co-author), Canadian section, Brussels European Employee Relations Consultants and HR Policy Association, May 2014.
  • "Supreme Court rules random alcohol testing not permitted without evidence of a significant workplace problem" (co-author), Brussels European Employee Relations Consultants and HR Policy Association, February, 2014.
  • "Top Ten 2023 Lessons Learned and the Road Ahead in Canadian Workplace Law," HR Policy Association Global Conference, Toronto, May 2023
  • "Collective Bargaining Trends," Global LERN, May 2023
  • "Bill 148: Ready or Not?" Norton Rose Fulbright Annual Workplace Law Conference, May 8, 2018
  • "The Pendulum Swings Left: Bill 148, Fair Workplaces, Better Jobs Act, 2017," Mercer Canada LERN, May 1, 2018
  • "Relationships with Non-Bargaining Unit Employees," Conference Board of Canada, Council of Industrial Relations Executive, June 15, 2017
  • "Dialogue with the Doctor: A Psychiatric Perspective on Workplace Mental Health Issues," Norton Rose Fulbright Annual Workplace Law Conference, May 9, 2017
  • Canadian Bar Association
  • Law Society of Upper Canada
  • The Advocates' Society
  • HR Policy Association (US)  
  • American Bar Association
  • Global LERN Centre of Excellence, Member, Board of Advisors