Mackenzie Hayden


 | Vancouver

Mac Hayden is an associate in the Aboriginal Law Group at Cassels. Mac’s practice focuses on Aboriginal, environmental, and regulatory law matters where he advises clients on issues related to Crown-Indigenous relations, Indigenous rights, Indigenous governance, and the Crown’s duty to consult. Mac’s practice also involves advising industry and provincial and municipal governments and agencies regarding project planning, obtaining necessary approvals including meeting regulatory and environmental requirements in project development. Mac also offers experience with judicial review proceedings before the Federal Court.

Mac brings unique insight to his clients’ challenges, having served as an advisor to both the Ontario government and the government of Canada, including as a Press Secretary and Policy Advisor to the federal Minister of Natural Resources.

Mac received his J.D. with distinction from the University of Ottawa. While in law school, Mac was named to the Dean’s Honour List, awarded for the faculty’s highest standing in Property Law, and served as an Associate Editor of the Ottawa Law Review. Mac also contributed to three interventions before the Supreme Court of Canada related to the constitutionality of the federal carbon pricing system on behalf of environmental and economic non-governmental organizations.

Prior to joining Cassels, Mac worked in the Vancouver office of a global law firm.

Select Indigenous-side Mandates

  • Representing an Indigenous governing body in drafting and negotiating a self-government agreement and related policy documents.
  • Representing Indigenous governing bodies at Crown-Indigenous negotiation tables aimed at protecting and advancing Aboriginal rights.
  • Representing Indigenous governing bodies in litigation proceedings concerning Aboriginal rights, and internal governance disputes.
  • Representing an Indigenous governing body in judicial review proceedings before the Federal Court related to an Act respecting First Nations, Inuit and Métis children, youth and families.
  • Representing an Indigenous governing body in negotiating impact benefit agreements for major mining projects within their traditional territory.
  • Advising Indigenous governing bodies on various Aboriginal law-related matters including harvesting and land rights, negotiations with the Crown, and the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP).
  • Advising an Indigenous governing body on the development of membership codes and other governance documents.

Select Industry-side Mandates

  • Representing industry proponents in drafting and negotiating impact benefit agreements.
  • Advising industry proponents on drafting and implementing proponent-specific Indigenous relations policies and strategies.
  • Advising industry proponents on various Aboriginal law-related matters, including the Crown’s duty to consult.
  • Advising industry proponents regarding contaminated site liabilities both on and off reserve.
  • Advising industry proponents regarding the impact of provincial water protection regimes on project development.
  • Advising industry proponents regarding trespass liability on reserve.
  • Advising industry proponents regarding federal proposals for a national benefits sharing framework in the extractive sector.

Select Public Sector Mandates

  • Representing a public government in a litigation proceeding concerning an assertion of Aboriginal rights infringement and an assertion of Aboriginal title.
  • Representing a federal agency in responding to an application for judicial review before the Federal Court.
  • Advising a public government on various Aboriginal law-related matters, including the applicability of provincial laws on reserve lands and the Crown’s duty to consult.
  • Advising a provincial regulator on the scope of their authority to consider the Crown’s duty to consult in certain regulatory proceedings.
  • Advising a regional transit operator regarding the expansion of service and infrastructure on reserve.
  • Advising a municipal government on aboriginal, environmental, and regulatory law related matters concerning the renewal of sewerage and water treatment infrastructure.