Cathy Guirguis

CEO and Partner

(416) 981-9347
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Cathy serves as the Chief Executive Officer and a partner at OKT. Her practice is focused on advancing Aboriginal and treaty rights through litigation and negotiation.

Cathy has represented clients in applications and actions in Ontario and Manitoba, as well as in federal court and at the Supreme Court of Canada. She has also represented Indigenous clients in proceedings and tribunals regarding election processes, labour and employment, and environmental assessment. Cathy provides negotiation advice regarding Aboriginal and treaty rights, land claims, and consultation, and she also advises clients on day-to-day employment matters and governance administration. She received her LL.B. from Osgoode Hall Law School, and also has a Masters of Environmental Studies.

While at law school, Cathy was a senior editor of the Osgoode Hall Law Journal and volunteered at Osgoode’s Community Legal Aid Services Program and Downsview Legal Aid Clinic. She also contributed to environmental projects at the Centre for Indigenous Environmental Resources (CIER), working on projects dealing with the duty to consult and accommodate, and indigenous environmental laws. Prior to law, Cathy worked in international development and has a background in journalism.

Cathy is a member of the Ontario bar and is listed as a "consistently recommended" lawyer in The Canadian Legal Lexpert Directory. She is also a member of The Advocates Society, and is currently serving as a member of the Mid-Career Advocates Standing Committee and the Standing Committee on Advocacy and Practice. Since 2022, Cathy has been an adjunct instructor at Osgoode Hall Law School.

The Services of Cathy Guirguis are provided through a Professional Corporation.

2024 LEXPERT-ranked Lawyer

Representative Work

  • Co-lead counsel representing the Saugeen Ojibway Nation in its Aboriginal title claim to water and claim about the Crown’s fiduciary breach and failure to protect their land (2023 ONCA 565 (CanLII) | Chippewas of Nawash Unceded First Nation v. Canada (Attorney General) | CanLII; 2021 ONSC 4181 (CanLII) | Saugeen First Nation v. The Attorney General of Canada | CanLII)
  • Lead counsel in a successful judicial review about Ontario’s failure to adequately consult and accommodate the Saugeen Ojibway in respect of aggregate mining in their traditional territory, including the failure to pay reasonable costs of the First Nations’ participation (Saugeen First Nation v. Ontario (MNRF), 2017 ONSC 3456 (CanLII))
  • Represented the Assembly of Manitoba Chiefs in its intervention at the Supreme Court of Canada regarding the Crown’s fiduciary duty to protect Indigenous lands in Williams Lake Indian Band v. Canada [2018] 1SCR 83
  • Represented Athabascan Chipewyan First Nation in responding to Canada’s application to enforce compliance with the First Nations Financial Transparency Act
  • Counsel for Pimicikamak in the Manitoba Court of Queen’s Bench and Manitoba’s Court of Appeal in defence of their rights to be consulted and accommodated about conveyance of culturally significant lands and sites
  • Represented Peguis First Nation in its participation at the Manitoba Clean Environment Commission hearings regarding the Keeyask Generation Project
  • Counsel for First Nations in election disputes about custom election codes in federal court
  • Represented the family in an inquest about an in-custody death of an Indigenous member of Pimicikamak in Thompson, Manitoba

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