What is the burden of proving consent to search?

We start with the principle that in the case of a warrantless arrest and search, the burden is upon the prosecution to establish justification such as a consent to search, under a recognized exception to the warrant requirement. This burden of proof must be sustained by the preponderance-of-the-evidence standard. (See People v. James (1977) 19 Cal.3d 99, 106, fn. 4, 137 Cal.Rptr. 447, 561 P.2d 1135; cf. Blair v. Pitchess (1971) 5 Cal.3d 258, 274, 96 Cal.Rptr. 42, 486 P.2d 1242.)