How does a class action lawsuit work in Ontario?

A class action is a lawsuit where one or more representative plaintiffs sue on behalf of a larger group of people who have suffered the same or similar harm. In Ontario, class actions are governed by the Class Proceedings Act, 1992. They are commonly used in cases involving product liability, data breaches, defective consumer products, securities fraud, or systemic institutional wrongdoing.

For a class action to proceed in Ontario, a court must first "certify" the proceeding — a procedural step where the court decides whether the case meets the legal requirements to proceed as a class action rather than as individual lawsuits. The certification motion examines whether there is a workable class of people with common issues, whether the claims are suitable for class treatment, and whether a class action is the preferable procedure.

If certified, all members of the class are automatically included unless they opt out. The case is then litigated by the representative plaintiff and class counsel on behalf of everyone. Class actions can take many years to resolve and typically settle rather than go to trial. Any settlement must be approved by the court to ensure it is fair to class members.

If you believe you may be part of an existing class action, you should look for notices of the proceeding and consider whether to opt out or remain in the class.