Marie Cossette, Ad. E.

Senior Partner
Norton Rose Fulbright Canada LLP

Marie Cossette, Ad. E.

Marie Cossette, Ad. E.



Marie Cossette has many years of experience with complex litigation files. A major component of Ms. Cossette's practice involves commercial and construction litigation. These cases raise a wide variety of technical issues and often involve managing complex expert evidence. Through her work in these areas of practice, Ms. Cossette has acquired extensive experience with issues relating to integrity, governance as well as ethical and professional conduct, particularly in the construction sector.

A second area of her practice covers public law, administrative law, professional liability and disciplinary law. She is regularly called to work on cases involving government relations in various forms. She has extensive experience relating to public inquiries (Chamberland Commission, Charbonneau Commission, Johnson Commission, Gomery Commission, and Poitras Commission). She served as counsel for the coroner's office during the public inquiry into a fire at the Résidence du Havre in L'Isle-Verte, Quebec. In addition, she acted as independent counsel for the Canadian Judicial Council during the public inquiry into Justice Michel Girouard. She also acts for various professional orders and professionals during disciplinary, professional liability (including for lawyers and engineers) and penal investigations as well as in matters concerning governance.

Concurrently with these more traditional practice areas, Ms. Cossette has experience managing media relations during media crisis and court cases. She has worked closely with public relations firms to ensure her clients' rights are respected while ensuring public relations imperatives are understood. She also has practical knowledge of the workings of the print, television, and radio media and regularly serves as a legal analyst for the Réseau de l'information (RDI) and Société Radio-Canada (Canadian broadcasters).

Professional experience

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LL.B., Université de Sherbrooke, 1990
B.A. (marketing and commercialization), UQAM, 2006
  • Quebec 1991

Matters in which Ms. Cossette has acted include:

  • Client support regarding ethical, governance and integrity issues (including regulatory investigations)
  • Client support in matters of crisis management and media relations
  • Counsel to highly publicized public inquiries (Chamberland, Charbonneau, Gomery, Johnson and Poitras commissions; Isle-Verte coroner's inquest; Canadian Judicial Council inquiry into Justice Michel Girouard)
  • Acting in cases involving construction law and tendering matters on behalf of major public and private sector project owners as well as contractors (claims, latent defects and poor workmanship, performance bonds, contracting disputes, termination, etc.)
  • Acting in commercial arbitration and commercial litigation (duty of loyalty and the misappropriation of business opportunities, shareholder agreements, termination of commercial leases, intellectual property in connection with research projects, manufacturer's liability, etc.)
  • Acting in civil liability class-actions
  • Acting in professional liability claims
  • Acting in disciplinary and penal matters
  • Best Lawyers in Canada: Administrative and Public Law (2019-2023)
  • Canadian Legal Lexpert Directory, 2016-2023: recommended in Litigation - Corporate Commercial; 2019-2023: recommended in Litigation - Regulatory & Public Law; 2022-2023: recommended in Professional Liability 
  • Canadian Legal Lexpert Directory Special Edition: leading lawyers in infrastructure (2021)
  • Avocate émérite by the Quebec Bar (Ad. E.)
  • Canadian Legal Lexpert Directory: Canada's leading litigation lawyers (2019)
  • Lexpert®/American Lawyer Guide to the Leading 500 Lawyers in Canada (2017)
  • Barreau de l'Université award and Barreau du Québec award, Sherbrooke University
  • "Lois et règlements en matière de marchés publics" (introduction), under the direction of Louis Bossé, Éditions Yvon Blais, 2018.
  • Various legal updates addressing corporate integrity and governance, 2015-2017.
  • "Understanding the organization and functioning of commissions of public inquiry to better influence them," Quebec Bar convention, 2010.
  • "Status and Role of Commission Counsel" (co-author Simon Ruel), The Law of Public Inquiries in Canada, Carswell, 2010.
  • Revision of manuscript of The Law of Public Inquiries in Canada by Simon Ruel, Carswell, 2010.
  • "The Role and Challenges of Commission Counsel," Proceedings of the 2009 CBA continuing education symposium on commissions of inquiry, Éditions Yvon Blais, volume 6, 2009.
  • "Appropriation of a Business Opportunity: Liability of Senior Management" (co-author Marc-André Sansregret), National magazine of the Canadian Bar Association and CBA PracticeLink, 2009.
  • "Précis de droit professionnel" (Summary of Professional Law), (co-author), Éditions Yvon Blais, 2007.
  • "Les impacts légaux concernant la gestion des médias sociaux," Corporate counsel forum and the CBA, 2019.
  • "Impact de la législation du cannabis sur l'exercice des diverses professions et le droit disciplinaire," co-speaker (co-chair, disciplinary law day), Open Forum, 2019.
  • "Les recours possibles dans le domaine des appels d'offres," co-speaker (co-chair), Open Forum, 2019.
  • "Crise médiatique : pas de panique mais soyez prêts," co-speaker, Chairman of the Bar Tour, Traditional and social medias: legal challenges, 2018.
  • "Les récentes décisions dans le domaine de la construction impliquant les secteurs publics et parapublics," co-speaker, Open Forum, 2018.
  • "Les développements en matière de conduites dérogatoires chez les professionnels," co-speaker (chair, disciplinary law day), Open Forum, 2018.
  • "S'exprimer pour convaincre et se démarquer," Leadership au féminin CCIQ, 2018.
  • "La résiliation unilatérale d'un contrat de construction par le client: les enjeux pour chaque partie," CEGQ Conference and Open Forum, co-chair, 2018 and Association des professionnels de la construction et de l'habitation du Québec, 2017.
  • "La protection des lanceurs d'alerte à l'égard des organismes publics," in-house conference, 2017.
  • "Présentation de la Loi favorisant la surveillance des contrats des organismes publics et instituant l'Autorité des marchés publics (Projet de loi 108)," Association des estimateurs et des économistes de la construction du Québec, 2017.
  • Canadian Bar Association
    • Communications committee, since 2009
    • Executive committee - Quebec division, 2011-2012
  • Fondation du musée national des beaux-arts
    • Chair, governance committee, since 2018
    • Director, since 2016
  • Member of the Advisory Committee of the Commissioner for Federal Judicial Affairs, 2017
  • Externat St-Jean-Berchmans
    • Member of the fundraising committee, since 2017
    • Scholarship committee campaign, honorary chair, 2016
  • Effet A - Femmes et ambition
    • Leader, Quebec cohort, since 2016
  • Chambre de commerce et d'industrie de Québec
    • Ambassador for the "Leadership au féminin" program, since 2017
    • Director, since 2013
    • Member of the business-culture committee, 2012-2017
  • Montreal and Quebec Bar
    • Organization committee, Congrès du Barreau, 2012-2013
    • Women in the legal profession Committee of the Bar of Montreal, 2009-2010
  • Cultural funding campaigns
    • ECM+, honorary chair, 2016
    • Théâtre Le Périscope, honorary chair, 2011
    • Théâtre La Veillée, honorary committee, 2009-2010