What is a trial court's obligation to instruct the jury with any affirmative defense supported by substantial evidence?

case are those principles closely and openly connected with the facts before the court, and which are necessary for the jury's understanding of the case."'" (People v. Breverman (1998) 19 Cal.4th 142, 154.) The trial court's sua sponte instructional duty includes the obligation to instruct the jury with any affirmative defense supported by substantial evidence, provided the defense is not inconsistent with the defendant's theory of the case. (People v. Salas (2006) 37 Cal.4th 967, 982; Breverman, supra, at p. 157.)