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

"In the absence of a request for a particular instruction, a trial court's obligation to instruct on a particular defense arises ' "only if [1] it appears that the defendant is relying on such a defense, or [2] if there is substantial evidence supportive of such a defense and the defense is not inconsistent with the defendant's theory of the case." ' [Citations.]" (People v. Dominguez (2006) 39 Cal.4th 1141, 1148.) Similarly, a trial court must give a requested instruction "only when the defense is supported by 'substantial evidence,' that is, evidence sufficient to 'deserve consideration by the jury,' not 'whenever any evidence is presented, no matter how weak.' " (People v. Williams (1992) 4 Cal.4th 354, 361.) "In determining whether the evidence is sufficient to warrant a jury instruction, the trial court does not determine the credibility of the defense evidence, but only whether 'there was

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evidence which, if believed by the jury, was sufficient to raise a reasonable doubt . . . .' [Citations.]" (People v. Salas (2006) 37 Cal.4th 967, 982-983.) On review, we independently determine whether substantial evidence to support a defense existed. (People v. Shelmire (2005) 130 Cal.App.4th 1044, 1055.)