In People v. McKinney (1986) 187 Cal. App. 3d 583, the defendant struck another prison inmate with a ball-peen hammer during a shop class. The defendant testified he assaulted the other prisoner because that prisoner had previously threatened him and was rumored to have a prison-made knife concealed in the shop. Under these circumstances, the court agreed with the trial court's rejection of defendant's attempt to present a necessity defense. The court stated it shared the view of the trial court "that the defense of necessity is inappropriate where it would encourage rather than deter violence. Violence justified in the name of preempting some future, necessarily speculative threat to life is the greater, not the lesser evil, particularly in the highly volatile environment of a prison institution." (Id. at p. 587.)