What is a class action lawsuit and how does it work in Ontario?

A class action is a type of lawsuit in Ontario where one or more representative plaintiffs bring a claim on behalf of a large group of people who have suffered similar harm from the same defendant (or defendants). Class actions are governed by the Class Proceedings Act, 1992 (Ontario) and allow plaintiffs who individually might have claims too small to pursue alone to aggregate their losses and litigate collectively.

Before a class action can proceed, the court must certify it — meaning the court determines that the case meets several criteria: there is an identifiable class of plaintiffs; the claims raise common issues of law or fact; a class proceeding is the preferable procedure; and there is a suitable representative plaintiff. Certification is not a determination of the merits; it decides the form of the proceeding.

If certified, class members are typically automatically included unless they opt out within a specified period. The representative plaintiff and their counsel advance the case on behalf of the class. Defendants in class actions face significant financial exposure because the aggregated claims can be very large.

Successful class actions can result in either a global settlement (paid to the class as a whole) or a judgment requiring individual damages assessments for each class member.