Ontario operates under a common law system, which relies on principles developed through prior court decisions. To ensure consistency, fairness, and finality, the legal system depends on two foundational doctrines: stare decisis and res judicata. These doctrines guide how courts interpret the law and determine when a matter has truly come to an end.
For employees navigating wrongful dismissal, severance disputes, or workplace discrimination, understanding these concepts can help in assessing strategy, risk, and what options remain available.
Why These Doctrines Matter for Employees
While “stare decisis” and “res judicata” may sound academic, they affect Ontario employees every day. Stare decisis matters because your severance, notice period, and employment rights come from past court decisions, not just legislation. Res judicata matters because once an issue has been decided by the Ministry of Labour, the Human Rights Tribunal, or a court, you may not be able to raise it again. These doctrines influence how much compensation you may receive, whether your employer can re-argue cause, and which legal forum you should choose first.
Stare Decisis: Building on Established Legal Principles
Stare decisis, meaning “to stand by things decided,” is the principle that courts must follow previous decisions. When a higher court establishes a legal rule, lower courts must apply it in similar cases. This creates consistency and predictability in the law.
There are two forms of stare decisis:
- Vertical stare decisis: Lower courts must follow decisions of higher courts (such as the Court of Appeal and the Supreme Court of Canada).
- Horizontal stare decisis: Courts at the same level generally follow each other’s decisions unless a prior ruling is clearly wrong or superseded by higher court reasoning.
Authoritative reference: Courts of Justice Act (CanLII).
Examples of Stare Decisis in Employment Law
- Bardal v. Globe & Mail Ltd. — established the “Bardal factors” for determining reasonable notice. Every modern wrongful dismissal analysis begins with this case. Learn more: Wrongful dismissal.
- M. v. HOJ Industries Ltd. — the Supreme Court held that termination clauses providing less than ESA minimums are void. Employers cannot rely on illegal clauses. Learn more: Termination clauses in Ontario.
These cases form the foundation for how courts resolve employment disputes today.
Res Judicata: Your Day in Court Is Final
Res judicata, meaning “a matter judged,” prevents parties from re-litigating issues or claims that have already been decided. This doctrine ensures that disputes come to an end and are not fought repeatedly in multiple forums.
Ontario applies res judicata through two main branches:
1. Cause of Action Estoppel
This prevents a person from starting a new lawsuit based on the same cause of action that has already been decided—or from raising claims they could have raised in the first proceeding.
Example: An employee alleging workplace discrimination may pursue a complaint under the Ontario Human Rights Code or include discrimination in a civil claim—but cannot litigate the same issue twice once a final decision has been made.
2. Issue Estoppel
Issue estoppel prevents parties from re-litigating specific issues that have already been decided. The requirements are:
1) the same issue, 2) a final decision, and 3) the same parties (or their privies).
Authoritative reference: Ontario Court of Appeal – Issue Estoppel Analysis.
Issue Estoppel in Real Employment Cases
Employment matters can involve different decision-makers—such as the Ministry of Labour, the Human Rights Tribunal of Ontario, or the civil courts. A finding in one arena can become binding in another.
Example: A worker dismissed for cause succeeds in a Ministry of Labour complaint, where the officer finds there was no cause. If the employer later attempts to argue just cause again in a civil lawsuit, the employee can use issue estoppel to stop them.
This happened in Desmarais v. Eat Your Cake Personal Health Delivery Inc., where the court refused to allow the employer to re-litigate cause after losing the issue in an earlier proceeding. Source: D. v. Eat Your Cake (CanLII).
Conclusion
Stare decisis and res judicata promote fairness, predictability, and finality in Ontario’s justice system. They ensure that similar cases are treated consistently and that once a matter has been decided, it cannot be repeatedly re-opened.
For employees, these doctrines directly influence severance outcomes, litigation strategy, and whether an employer can revisit issues such as just cause. Understanding how they operate helps individuals make informed decisions about their rights and legal options.