This is a photo of Claire Seaborn photo




Contact by email at [email protected]

t. +1 416-601-8852


Law School

University of Ottawa

Bar Admission

Ontario, 2015
England & Wales, 2018

Clients trust Claire to successfully navigate complex legal disputes and government regulation.

Claire’s litigation practice focuses on commercial disputes, public law and regulatory matters. She draws from her experience in the public and private sectors in Canada, the United States and the United Kingdom. Claire’s involvement in high-profile and high-stakes files has sharpened her ability to advocate for her clients and provide sound legal advice.

Claire has recently returned to McCarthy Tétrault after working as a senior advisor to Canada’s Minister of Environment and Climate Change, where she provided advice on legal and regulatory affairs. In this role, Claire supported the Minister in her obligations to Cabinet, the Parliament of Canada and three federal departments, which notably included the constitutional challenges to the Greenhouse Gas Pollution Pricing Act.

Prior to joining the firm, Claire worked in the London, UK office of a New York law firm where she gained experience with commercial arbitration and investor-state disputes. Claire also spent six months working on foreign policy at the Embassy of Canada in Washington, DC after completing her undergraduate degree in political science at the University of British Columbia.

Claire is a skilled advocate inside and outside the courtroom. She has appeared as an expert witness three times before the House of Commons Finance Committee, and has frequently been cited in national media regarding workplace rights. Claire was a consultant for the IBA Presidential Task Force on Climate Change and Human Rights, and is presently Canada’s national representative on the IBA Young Lawyers’ Committee. She regularly acts as duty counsel with Pro Bono Ontario at the Ontario Superior Court of Justice.


  • represented an electricity distributor in a commercial dispute related to a public inquiry in the Town of Collingwood
  • represented a commercial real estate developer in defence of regulatory charges under a municipal by-law
  • represented an energy company in a contractual dispute: Bruce Power v BNT Canada, 2018 ONSC 5968
  • represented a mining company in an appeal from a municipal order: FNX Mining v Sudbury, 2018 ONSC 4912
  • represented a foreign national in a judicial review application concerning sanctions law: Portnov v Canada (Foreign Affairs), 2018 FC 1248
  • represented an energy company in a commercial arbitration arising from exploration activities that occurred in Europe
  • represented various businesses in their submissions to Global Affairs Canada regarding the US steel and aluminum tariffs
  • represented a global construction firm in a multi-party dispute regarding the construction of Union Station, Canada’s busiest transport hub: Carillion et al v Toronto, 2018 ONSC 3918
  • represented a defendant in a professional negligence claim: Baldwin v Vaidyanathan, 2017 ONSC 6645