What is the duty of a trial judge to give instructions on particular defenses and their relevance to the charged offense?

It is also well established that "the duty to give instructions, sua sponte, on particular defenses and their relevance to the charged offense arises only if it appears that the defendant is relying on such a defense, or if there is substantial evidence supportive of such a defense and the defense is not inconsistent with the defendant's theory of the case. Indeed, this limitation on the duty of the trial court is necessary not only because it would be unduly burdensome to require more of trial judges, but also because of the potential prejudice to defendants if instructions were given on defenses inconsistent with the theory relied upon." (People v. Sedeno (1974) 10 Cal.3d 703, 716, 112 Cal.Rptr. 1, 518 P.2d 913.)