Guillaume Sirois
Available in: English Français
Originally from Gatineau, Guillaume is now a committed member of the Power Law team. His expertise, spanning the areas of public law, litigation and the preservation of the rule of law, is reflected in his diverse background. His unwavering commitment to respect for the rule of law by state actors is at the heart of his professional approach.

Guillaume has significant experience in the field of litigation, public and administrative law and particularly commissions of inquiry. He is currently representing a diaspora organization before the Foreign Interference Commission, dealing with matters of national security, integrity of elections and democratic institutions, and how these issues disproportionately impact the diaspora. Guillaume previously served as Commission counsel on the Public Order Emergency Commission where his work focused primarily on the actions of major police services in Canada and certain municipalities in response to the Freedom Convoy protests.

While serving at the Commission on Relations between Indigenous Peoples and Certain Public Services, Guillaume played an active role in designing targeted interrogations, especially focused on police and health services in Québec. This inquiry aimed to shed light on the complex interactions between government agencies, public services and Indigenous communities, with the aim of highlighting any form of systemic discrimination and fostering mutual understanding.

Guillaume also has significant experience in tax and public litigation, which he acquired as a lawyer for the Department of Justice of Canada, representing the government’s interests in a large variety of cases, including tax residency, high net worth assessments, transfer pricing and resources taxation.

Guillaume also clerked at the Federal Court and volunteered for Lawyers Without Borders Canada in Ivory Coast.

Passionate about defending the rule of law while serving the best interest of his clients, values ​​dear to Power Law, Guillaume brings solid experience to the team. His fluency in French and English as well as his ability to collaborate within multidisciplinary teams make him a valuable asset.

Guillaume practices law in French and English, and has a basic knowledge of Russian.

Law Societies

  • Quebec
  • Ontario


  • LL.B. (Université de Sherbrooke – 2018)

Guillaume In the News

Put a combination of knowledge, experience, and creativity to work for you.