Several years ago I represented a young man who was charged with murder. He was in the passenger seat of a car being driven by a man who was selling drugs to him. The driver had suddenly reached into his coat pocket and the defendant drew his gun, shot and killed him thinking that the man was reaching for a gun. The driver turned out to have been a confidential police informant.
At trial the defense of self-defense was successfully raised as the jury was persuaded that the defendant was in reasonable fear of great bodily injury.