The United States government (plaintiff) prosecuted Eugene Pete Garcia, Joe Anthony Contreras, and David Lucero (defendants), all of whom were prison inmates, for the second-degree murder of another inmate, Michael Martinez, in violation of 18 U.S.C. § 1111. The trial evidence established that Martinez had previously threatened Garcia's life. Garcia armed himself with a knife, in preparation for a showdown with Martinez. Contreras and Lucero testified that as Garcia approached Martinez, Martinez pulled out his own knife and began attacking Garcia. The fight soon spilled into a corridor, where prison guards ordered the men to stop. Garcia, Contreras, and Lucero ignored the order. The guards saw the three men chase and catch Martinez. Contreras and Lucero held Martinez down while Garcia stabbed him to death. Garcia claimed he acted in self-defense, and Contreras and Lucero claimed that they merely helped Garcia defend himself. The judge instructed the jury that if they found that Garcia provoked Martinez's attack, self-defense excused the fatal stabbing only if Garcia reasonably believed that he was in mortal danger, and only if he had first exhausted every reasonable defensive measure short of deadly force. The jury convicted all three men. On appeal to the Seventh Circuit Court of Appeals, Garcia contended that there was no evidence that he provoked Martinez's attack, and therefore the issue of provocation should not have been submitted to the jury.