How do I serve a lawsuit if I don't know the identity of the defendant in Ontario?

Ontario law allows a claim to be started against an unidentified defendant, often described in the pleading using a placeholder name such as "John Doe" or "Jane Doe," where the plaintiff genuinely doesn't yet know who's responsible but has enough information to describe the conduct or role involved. This comes up, for example, in claims against an anonymous online poster, an unidentified driver, or someone whose identity is only discoverable through information held by a third party. Actually serving an unidentified person obviously isn't possible in the usual sense, so the practical path is to first identify them, often through a separate motion asking a third party, such as an internet service provider or platform, to disclose identifying information.

Once the person's real identity is established, the pleading is generally amended to name them properly, and service then proceeds in the ordinary way against that now-identified defendant. Courts are alert to the risk that this route could be misused to pressure or harass someone before a real case against them is established, so the plaintiff typically needs a genuine, good-faith basis for the claim before a court will order a third party to reveal identifying details. This process can add real time and cost to a case before service is even possible.