Mary Buttery, KC

Mary is a partner in the Disputes Group at Osler. She is an experienced commercial litigator specializing in complex, multi-party commercial litigation and class actions, along with noted expertise in restructuring and insolvency, the enforcement of foreign judgments and fraud.

In addition, Mary represents financial institutions, debtors and creditors, receivers and trustees in matters related to debt restructuring, corporate reorganizations, loan workouts, fraudulent preference actions, bankruptcy and receiverships and regularly advises clients who are experiencing financial difficulty, or whose customers’ or suppliers’ insolvency affects their business. She has appeared in all levels of courts across Canada and has been lead counsel in the Supreme Court of Canada.

Mary served as counsel in class action matters involving opioids, automobile wire harnesses and lithium-ion battery price fixing. She is recognized nationwide for her involvement in countless prominent litigation matters and many significant insolvency files. Mary has extensive experience in many different sectors, most notably, cannabis, mining, retail, real estate, forestry and natural resources.

Mary is recognized by numerous legal directories as a leader in her field and has served as an Adjunct Professor of Law at the University of British Columbia, where she taught insolvency law to upper-year students. Mary was recognized by Lexpert as a “Rising Star – Leading Lawyer Under 40” and received the publication’s Zenith Award in 2013. She is also recognized as one of the Top 100 Women in Litigation by Benchmark Canada and has authored several articles on varied topics in her area of practice. In 2018, Mary was appointed King’s Counsel in British Columbia.

Representative Work

  • The court-appointed Monitor in the Companies Creditor Arrangement Act (“CCAA”) proceedings of Mountain Equipment Co-Op
  • A licensed cannabis producer in its CCAA proceedings
  • Counsel for Pandion Mine Finance in the receivership of Otso Gold Corporation
  • The board of directors of Trevali Mining Corporation’s CCAA proceedings
  • Walter Canada Energy Holdings, Inc. in its restructuring under the CCAA
  • A major US-based gold mining group in its cross-border insolvency pursuant to Part IV of the CCAA
  • The court-appointed Monitor of Yukon Zinc Corporation and the court-appointed Receiver of Maple Leaf Loading, a multi-jurisdictional trucking company
  • The court-appointed liquidator in world-wide liquidation and asset tracing proceedings with proceedings in Australia, Hong Kong, London and the Cayman Islands
  • Counsel to the Government of the Northwest Territories in relation major insolvency matters

Latest Insights

  • Video Jan 9, 2024

    Business considerations in litigation

    When faced with a dispute, businesses must weigh a variety of factors to know what action to take. If you receive a claim, or think you have a claim...

    Read more
    Business considerations in litigation
  • Osler Update Jan 8, 2024

    B.C. Court of Appeal lowers the bar for dismissal for delay

    A recent British Columbia Court of Appeal decision revisited a decades-old test for dismissing an action for want of prosecution, and could give B.C....

    Read more
    B.C. Court of Appeal lowers the bar for dismissal for delay
  • Osler Update Apr 25, 2023

    Traditional Indigenous Knowledge in Canadian law (webinar)

    In the April session of our Indigenous Law Insights webinar series, Osler partners Richard King and Mary Buttery, KC, discussed the role of...

    Read more
  • Webinar Apr 25, 2023

    Indigenous Law Insights: Creating partnerships within Indigenous communities and use of traditional knowledge in project approvals

    In the April session of Osler’s Indigenous Law Insights webinar series, partners Richard King (Co-Chair, Regulatory, Indigenous and Environmental)...

    Read more
    Indigenous Law Insights: Creating partnerships within Indigenous communities and use of traditional knowledge in project approvals
View all Insights

Awards and Recognition

  • Benchmark Canada: Recognized as Litigation Star: Insolvency, Top 100 Women in Litigation: Canada, and Insolvency Litigator of the Year Award: 2021
  • Best Lawyers in Canada: Recognized as Lawyer of the Year for Insolvency and Financial Restructuring Law – Vancouver
  • Best Lawyers in Canada: Recognized in Insolvency and Financial Restructuring; Corporate and Commercial Litigation
  • Canadian Legal Lexpert Directory (Insolvency & Financial Restructuring – Insolvency Litigation; Insolvency & Financial Restructuring – Financial Restructuring)
  • Chambers Canada: Recognized in Restructuring/Insolvency
  • Chambers Global: Recognized in Restructuring/Insolvency
  • IFLR1000: Recognized in Restructuring & Insolvency
  • Legal 500 Canada: Recognized as a Leading Individual in Restructuring and Insolvency
  • Who’s Who Legal: Canada: Recognized in Restructuring & Insolvency

Media Mentions

  • Osler News Aug 3, 2023

    Four Osler partners recognized in Benchmark Canada’s ‘Top 100 Women in Litigation’

    Osler congratulates partners Maureen Killoran, KC, Mary Buttery, KC, Teresa Tomchak and Laura Fric for their inclusion in the Benchmark Canada’s...

    Read more
  • Osler News Sep 6, 2022

    Mary Buttery, QC joins Osler’s Litigation Group in Vancouver as a Partner

    Osler is pleased to welcome Mary Buttery, QC to the Litigation Group in our Vancouver office.

    Read more

Community Involvement

  • Southlands Riding Club, Board of Directors (Current)
  • Climate Governance Expert, Canadian Climate Law Initiative (Current)
  • BC Cancer Foundation, Board of Directors, Member (Former)
  • Collingwood School, Class Parent Volunteer (2008-2015)
  • Minerva Foundation for B.C. Women’s Follow A Leader Program (recognized in the Vancouver Sun for her community leadership in association with this role) (Former)
  • West Vancouver Field Hockey Association, Assistant Coach (2012-2016)
  • Vancouver Aquarium, Board of Governors, Member (Former)

Speaking and Writing

Published Work

  • Chair, Annual Conference 2022, Insolvency institute of Canada
  • Benchmark Litigation’s Women in Litigation Vancouver Forum: Featuring Expert Insights from Mary Buttery
  • Annual Review of Insolvency Law, Presenter
  • CAIRP Annual Conference, Presenter



  • LL.B., University of Windsor


  • English

Professional Affiliations

  • American Bankruptcy Institute
  • Annual Review of Insolvency Law, Editorial Board
  • British Columbia Law Society
  • Canadian Association of Insolvency and Restructuring Professionals (CAIRP), Editorial Advisory Board
  • Canadian Bar Association, B.C. Branch, Civil Litigation, Insolvency & Banking Subsections
  • Continuing Legal Education Society of British Columbia, Lecturer
  • Insolvency Institute of Canada (IIC)
  • International Insolvency Institute (III)
  • Law Society of Ontario
  • Turnaround Management Association (TMA)
  • University of British Columbia Law School, Former Adjunct Professor