What is the substantial evidence required to prove beyond a reasonable doubt in a criminal case?

In applying the substantial evidence standard of review, the appellate court adopts all reasonable inferences and presumes in support of the judgment the existence of every fact that a jury reasonably could have deduced from the evidence. Generally, the testimony of a single witness is sufficient to prove a disputed fact. (People v. Young (2005) 34 Cal.4th 1149, 1181.) The trier of fact makes credibility determinations and resolves factual disputes. An appellate court will not substitute its evaluation of a witness's credibility for that of the fact finder. "It is the jury, not this court, that must be convinced beyond a reasonable doubt that the gang enhancement allegation is true. [Citation.]" (Vazquez, supra, 178 Cal.App.4th at p. 352.)

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