The nexus requirement holds that an act that is considered joint activity must have some relationship to the act of justice that the defendant is seeking to avoid.
The prosecutor must prove that the defendant acted on the basis of common sense necessary for the crime when he committed the voluntary act (or unlawful omission) necessary for the crime.
An error as to material fact may give rise to reasonable suspicion that the defendant possessed the degree of nexus requirements in the human common sense necessary to impose criminal responsibility so that such an error would be considered a lack of evidence. It is true that it is sometimes used as a defense.
