What is a motion for non-suit during a trial in Ontario?

A motion for non-suit is brought by a defendant partway through a trial, after the plaintiff has finished presenting all of their evidence but before the defendant has called any evidence of their own. The defendant argues that, even taking the plaintiff's evidence at its strongest and most favourable light, it simply isn't enough to legally support the claim, so the case should be dismissed without the defendant needing to put on a defence at all. The judge isn't deciding who's more believable at this stage; the question is narrower — whether there's enough evidence that a claim could succeed even before weighing credibility or competing evidence.

Bringing this motion carries a real strategic risk in a case with a jury: in that setting, a defendant who brings the motion and loses may be required to elect whether to call evidence in their own defence, giving up the chance to argue insufficiency of the plaintiff's case again at the end of trial. In a judge-alone trial, that specific procedural risk is generally reduced, since the judge can normally consider the sufficiency argument again at the end regardless. Because of this, deciding whether to bring a non-suit motion, and when, is a significant tactical decision made with legal advice.