What is the standard of review for a motion?

On the question of whether the motions judge applied the appropriate test, the standard of review is correctness. On the exercise of the powers to weigh evidence, evaluate credibility and draw inferences from the evidence, the standard is palpable and overriding error. In Hryniak v. Mauldin, 2014 SCC 7, at paras. 81-84, Karakatsanis J. explained the rationale for the standard of review in the following terms:

In my view, absent an error of law, the exercise of powers under the new summary judgment rule attracts deference. When the motion judge exercises her new fact‑finding powers under Rule 20.04(2.1) and determines whether there is a genuine issue requiring a trial, this is a question of mixed fact and law. Where there is no extricable error in principle, findings of mixed fact and law should not be overturned absent palpable and overriding error: Housen v. Nikolaisen, 2002 SCC 33, [2002] 2 S.C.R. 235, at para. 36.