How do I find out if someone has been sued in Canada?
It depends on the province. In British Columbia, search Court Services Online by party name. In Québec, search the plumitifs through SOQUIJ. In Ontario and Alberta there is no equivalent public online search, so you check CanLII for any reported decision and then either attend the relevant courthouse registry or have someone do it for you. Sleuthify runs the online sources and identifies which courthouses to visit.