What is the test for “overriding error” in the context of a challenged finding of fact?

An ‘overriding’ error is an error that is sufficiently significant to vitiate the challenged finding of fact. Where the challenged finding of fact is based on a constellation of findings, the conclusion that one or more of those findings is founded on a ‘palpable’ error does not automatically mean that the error is also ‘overriding.’ The appellant must demonstrate that the error goes to the root of the challenged finding of fact such that the fact cannot safely stand in the face of that error: Schwartz v. Canada, 1996 CanLII 217 (SCC), [1996] 1 S.C.R. 254 at 281.