What is the effect of standards of review and other procedural tools on appeal?

It is true, as respondent observes, that on appeal Lopez "will reap the benefit of standards of review and other procedural tools that are designed to protect the ruling the trial court has already made." But the effect of these "procedural tools" should not be overstated; there are limits to how much an appellate court can or should defer to a trial courts conclusions. (See, e.g., Kavanaugh v. West Sonoma County Union High School Dist. (2003) 29 Cal.4th 911, 916, 129 Cal.Rptr.2d 811, 62 P.3d 54 [on appeal, a court defers to the trial courts factual determinations if supported by substantial evidence, but reviews questions of law de novo].) Here, for example, we are concerned with a Fourth Amendment suppression ruling regarding evidence obtained without a warrant; in such cases, an appellate court independently applies the law to the trial courts factual findings, determining de novo whether the findings support the trial courts ruling. ( People v. Loewen (1983) 35 Cal.3d 117, 123, 196 Cal.Rptr. 846, 672 P.2d 436.) The effect of standards of review and other procedural tools is, moreover, often open to reasoned debate; in our adversarial system of justice, we ordinarily depend on the

[6 Cal.5th 1007]