What is the accident defense against criminal culpability?

Under section 26, subdivision (5), an exception to criminal culpability applies to "[p]ersons who committed the act or made the omission charged through misfortune or by accident, when it appears that there was no evil design, intention, or culpable negligence.'" (People v. Gonzales (1999) 74 Cal.App.4th 382, 390.) "The accident defense is a claim that the defendant acted without forming the mental state necessary to make his action a crime." (Ibid.)