What is a third party culpability instruction in a criminal case?

A third-party culpability instruction is a pinpoint instruction on a defense theory of reasonable doubt. (People v. Hartsch (2010) 49 Cal.4th 472, 504.) The trial court is not required to give a pinpoint instruction that is argumentative or duplicates other instructions. (Id. at p. 500.) Third party culpability instructions "add little to the standard instruction on reasonable doubt." (Id. at p. 504.) "It is hardly a difficult concept for the jury to grasp that acquittal is required if there is reasonable doubt as to whether someone else committed the charged crimes." (Ibid.) Thus, "[e]ven if such instructions properly pinpoint the theory of third party liability, their omission is not prejudicial because the reasonable doubt instructions give defendants ample opportunity to impress upon the jury that evidence of another party's liability must be considered in weighing whether the prosecution has met its burden of proof." (Ibid.)