What are pleadings in an Ontario civil lawsuit?

Pleadings are the formal documents exchanged between the parties in the early stage of a civil lawsuit that define what each side is claiming or defending. In Ontario, the main pleadings in a Superior Court proceeding are the statement of claim (filed by the plaintiff), the statement of defence (filed by the defendant), and any reply the plaintiff files in response to the defence.

If the defendant has a claim against the plaintiff, they include a counterclaim in their defence. If there are third parties being added to the proceeding, additional pleadings are exchanged with those parties.

Pleadings serve a critical purpose: they define the issues and frame the case. Evidence and argument at trial are generally limited to what the pleadings put in issue. A party cannot surprise the other side at trial with a theory of the case not disclosed in the pleadings. If important facts emerge during litigation, pleadings can be amended with the court's permission or the other side's consent.

The Rules of Civil Procedure require pleadings to state "material facts" (the key facts giving rise to the claim or defence) but not evidence (how those facts will be proven). The distinction matters — a pleading that reads like an evidence brief is not properly structured. Properly drafted pleadings are the foundation of a well-run civil case.