What is the legal test for certifying a class action in Ontario?

Under Ontario's Class Proceedings Act, 1992, a proposed class action generally can't proceed as a class proceeding until a court certifies it, which involves satisfying several requirements together rather than any single factor being enough on its own. The pleading generally needs to disclose a genuine cause of action, there needs to be an identifiable class of people the claim is being brought on behalf of, and there need to be common issues that are genuinely shared across the proposed class members, rather than each person's claim depending entirely on their own individual circumstances.

The court also generally needs to be satisfied that proceeding as a class action is the preferable way to resolve the claims, considering realistic alternatives such as individual lawsuits, and that a suitable representative plaintiff exists who can fairly and adequately represent the class's interests, generally including having a workable plan for how the litigation would actually proceed. Certification is a genuinely significant procedural hurdle in its own right, distinct from the merits of the underlying claim, and a proposed class action that fails certification generally can't proceed as a class proceeding even if the underlying allegations might otherwise have some merit.