Brown v. United States. 256 U.S. 335 (1921) involved a long-standing dispute between Brown and his co-worker. Id. at 342. Due to their troubled history, Brown brought a gun to work for protection. Id. Shortly thereafter, Brown and his co-worker got into an altercation. Id. The co-worker attacked Brown and began punching him. Id. In response, Brown ran to his gun, which was in his coat pocket approximately twenty feet away, and fired four shots at his co-worker, killing him. Id. At trial, Brown was convicted of second-degree murder after the trial court instructed the jury that "in considering the question of self defense . . . the party assaulted is always under the obligation to retreat so long as retreat is open to him, provided that he can do so without subjecting himself to the danger of death or great bodily harm." Id. On appeal, the United States Supreme Court reversed Brown's conviction, holding that defendants have no duty to retreat when they face a reasonable fear of imminent death or severe bodily harm. Id. at 343-44.