What is the legal test for applying palpable and overriding error standard in appellate review of findings of fact and of mixed fact and law?

The underlying reasons for applying a palpable and overriding error standard in appellate review of findings of fact and of mixed fact and law were exhaustively reviewed by the majority in Housen. These reasons include: (i) the trial judge is in the better position to assess witnesses' credibility at trial; (ii) unlimited intervention by appellate courts would greatly increase the number and length of trials generally; (iii) substantial resources are allocated to the trial courts' process of assessing facts; (iv) it is important to preserve the autonomy and integrity of the trial process by deferring to a trial judge's finding of facts. See Housen at paras. 12 and 13. See also Schwartz v. Canada, 1996 CanLII 217 (SCC), [1996] 1 S.C.R. 254, [1996] S.C.J. No. 15, at para. 32. [page676]