What is the appellate court's role when presented with a claim of insufficient evidence?

An appellate court's role when presented with a claim of insufficient evidence has long been scripted. The court must review the record in the light most favorable to the judgment to determine whether there is substantial evidence from which the trier of fact could have found each element of the crime beyond a reasonable doubt, and the court must not reweigh the evidence, reassess the credibility of the witnesses, or substitute its conclusions for those reached reasonably in the lower court. (See, e.g., People v. Snow (2003) 30 Cal.4th 43, 66; People v. Jones (1990) 51 Cal.3d 294, 314.)