What is the test for instructing a jury on a defense?

A trial court must instruct, sua sponte, on a particular defense " 'if there is substantial evidence supportive of such a defense and the defense is not inconsistent with the defendant's theory of the case.' " (People v. Barton (1995) 12 Cal.4th 186, 195.) Substantial evidence supporting a defense is "evidence sufficient for a reasonable jury to find in favor of the defendant . . . ." (People v. Salas (2006) 37 Cal.4th 967, 982.) We independently review an alleged failure to provide an instruction about a defense. (Cf. People v. Waidla (2000) 22 Cal.4th 690, 733 ["An appellate court applies the independent or de novo standard of review to the failure by a trial court to instruct on an uncharged offense that was assertedly lesser than, and included, in a charged offense."].)