Share on LinkedInShare on LinkedIn

ARTICLE · 08 MAY 2026

Finality Reaffirmed: The Supreme Court Clarifies Res Judicata

McCarthy Tétrault
McCarthy Tétrault
Contributor
McCarthy Tétrault

McCarthy Tétrault

Built on a unique model of collaboration, innovation and efficiency, McCarthy Tétrault delivers...

View firm profile
Explore more from McCarthy Tétrault

The Supreme Court of Canada has clarified the test for res judicata and cause of action estoppel, establishing when parties can be barred from relitigating issues. This real estate financing dispute explores whether a party must explicitly invoke res judicata at first instance, how courts determine if two proceedings involve the same cause of action, and what constitutes reasonable diligence in advancing all available legal arguments.

CanadaLitigation, Mediation & Arbitration
Canadian Appeals Monitor
Canadian Appeals Monitor
Erin Chesney
Erin Chesney
Michelle De Haas
Michelle De Haas
Kosta Kalogiros
Kosta Kalogiros
Adam Goldenberg
Adam Goldenberg
Author LinkedIn connections

In Patrick Street Holdings Ltd. v. 11368 NL Inc. (judgment released on May 8, 2026), the Supreme Court of Canada clarified the test for applying an ancient litigation principle: you do not get a second kick at the can.

The bottom line

  • Duty to raise res judicata promptly: The Court reaffirmed that parties must raise res judicata at the earliest reasonable opportunity, but clarified that this requirement is not one of form, but of substance: a party must put the material facts underlying the defence in issue early, even if the doctrine is not explicitly named. That being said, it is prudent to be as explicit at possible to minimize ambiguity or uncertainty, and to ensure that parties are not barred from raising the argument at a later stage.

We operate a free-to-view policy, asking only that you register in order to read all of our content. Please login or register to view the rest of this article.

Register for freeORLog in

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

View source

Related Articles

Legal Intelligence Newsletters: sign up for the latest legal and regulatory news on your chosen topics

Read more about

Related Comparative Guides

See more popular content from

Article

The Coldcard Exploit: Why Victims May Have Two Routes To Recovery

A five-year-old firmware defect in Coldcard hardware wallets has enabled attackers to systematically drain an estimated $116 million in Bitcoin from over 5,200 victims since July 2026. This unprecedented exploit raises critical questions about manufacturer liability and creates two distinct legal pathways for recovery: blockchain tracing against the perpetrators and potential litigation against Canadian manufacturer Coinkite for product defects that undermined the fundamental security promise of devices mar
CanadaLitigation, Mediation & Arbitration
WeirFoulds LLP
WeirFoulds LLP
Article

Plaintiffs Awarded A Total Of $800,000 In Damages For Defamation (Murdy v. Barrette)

A Canadian court awarded $800,000 in damages to a couple defamed by serious false allegations of sexual assault and criminal misconduct spread through social media. The case examines how factors like the severity of accusations, use of social media platforms, and a defendant's failure to mount a defense can dramatically escalate defamation damages beyond typical awards.
CanadaLitigation, Mediation & Arbitration
Gardiner Roberts LLP
Gardiner Roberts LLP
Article

Ontario’s New AI Rules: What Lawyers And Expert Witnesses Need To Know

Ontario's Rules of Civil Procedure now include strict amendments requiring lawyers and expert witnesses to certify the authenticity of every citation and authority used in court materials. These new anti-hallucination provisions impose significant penalties for presenting AI-generated fabricated authorities, fundamentally shifting accountability for artificial intelligence use in litigation.
CanadaLitigation, Mediation & Arbitration
Soloway Wright
Soloway Wright
Article

Not Beyond Reproach: Alberta Court Confirms Jurisdiction Over Alberta Energy Regulator

The Alberta Court of King's Bench has confirmed its jurisdiction to grant injunctive relief against the Alberta Energy Regulator despite a broadly worded statutory privative clause. This landmark decision, arising from Sumerian Oil & Gas's application to stay a suspension order affecting approximately 900 wells, represents one of the first considerations of the Supreme Court of Canada's recent Democracy Watch ruling and may significantly impact future disputes involving AER orders.
CanadaLitigation, Mediation & Arbitration
MLT Aikins LLP
MLT Aikins LLP
Article

Gloves Off: Canada Answers U.S. Section 338 Tariffs Dollar-for-Dollar As Washington Escalates With Import Bans

Canada and the United States have entered a new phase of trade conflict, with Canada implementing retaliatory surtaxes on C$27.6 billion of U.S. goods while the United States escalates beyond tariffs to outright import prohibitions on Canadian alcohol, dairy products, and motorcycles. The dispute now extends into government procurement policy, raising questions about compliance strategies and supply chain restructuring as both nations tighten customs enforcement.
CanadaInternational Law
McCarthy Tétrault
McCarthy Tétrault
Article

Federal Government Removes Certain Energy Projects From The Impact Assessment Act Project List

The Canadian government has removed seven types of energy projects from federal impact assessment requirements, shifting review responsibilities to the Canada Energy Regulator and provincial processes. This regulatory change affects pipelines, electrical transmission lines, oil sands facilities, and power plants, fundamentally altering how major energy infrastructure projects will be evaluated and approved across Canada.
CanadaEnvironment
McCarthy Tétrault
McCarthy Tétrault
Article

Canada Commits To Airport Privatization Through Long-Term Concessions For Its Four Largest Airports

The Canadian federal government has announced a firm commitment to privatize operations at the country's four largest airports through long-term concessions, marking a decisive shift from earlier exploratory discussions. Prime Minister Mark Carney revealed that while the government will retain ownership of airport lands and assets following the Australian leased-airport model, private investment will be sought to operate Toronto Pearson, Vancouver, Montreal-Trudeau, and Calgary international airports.
CanadaTransport
McCarthy Tétrault
McCarthy Tétrault
Article

FITAA Is Now In Force: What Organizations Need To Know About Canada's New Foreign Influence Registry

Canada's Foreign Influence Transparency and Accountability Act (FITAA) establishes a comprehensive registration regime for arrangements with foreign principals involving influence activities related to Canadian political or governmental processes. Organizations across sectors—including businesses, NGOs, universities, and industry associations—must assess whether their existing or proposed arrangements trigger registration obligations, with significant administrative and criminal penalties for no
CanadaInternational Law
McCarthy Tétrault
McCarthy Tétrault
Article

Changing Lanes: Canada Proposes To Replace Its ZEV Sales Mandate With Technology-neutral Emission Standards

Canada is proposing to eliminate its federal zero-emission vehicle sales mandate and replace it with technology-neutral greenhouse gas emission standards. The shift comes amid declining EV sales, affordability concerns, and trade uncertainty with the United States, raising questions about how the automotive industry will balance climate goals with market realities. What will this regulatory transformation mean for manufacturers, consumers, and Canada's electrification timeline?
CanadaEnvironment
McCarthy Tétrault
McCarthy Tétrault