State v. Levin
In State v. Levin, 2006 UT 50, P 25, 144 P.3d 1096, the Court set out a policy-based balancing test for determining the amount of deference that appellate courts should pay to trial courts when reviewing mixed questions of law and fact.
The tripartite test considers:
(1) the complexity of the facts;
(2) the degree to which the trial court relied on observable facts that cannot be reflected adequately in the record, such as witness demeanor and appearance;
(3) policy reasons that favor the exercise of discretion by the lower courts. Id.