Tison v. Arizona, 481 U.S. 137 (1987), is a United States Supreme Court case in which the Court qualified the rule it set forth in Enmund v. Florida (1982). Just as in Enmund, in Tison the Court applied the proportionality principle to conclude that the death penalty was an appropriate punishment for a felony murderer who was a major participant in the underlying felony and exhibited a reckless indifference to human life. Factual background This case stems from an infamous prison break during the summer of 1978. Gary Tison was serving a life sentence at the Arizona State Prison in Florence for killing a prison guard. His three sons, Donald, Ricky, and Raymond, plotted to break him and his cellmate, Randy Greenawalt, out of prison. On July 30, 1978, the sons entered the prison for a visit, taking advantage of a policy that allowed an informal picnic setting for weekend family visits, carrying an ice chest packed with revolvers and sawed-off shotguns. One of them aimed a sawed-off shotgun at a lobby guard. Greenawalt helped in the escape by cutting off telephones and alarm systems. They escaped in Donald Tison's 1969 Lincoln Continental, but the next day, one of the Lincoln's tires blew out on a stretch of road not far from the California border, near Quartzsite. Marine Sgt. John Lyons, 24, of Yuma, traveling with his wife, son, and niece on his way to visit family in Nebraska, stopped to help. While Raymond Tison was showing John Lyons the flat tire, the other escapees emerged from the brush. Raymond forced the Lyonses into the Lincoln, and then he and Donald drove the Lincoln down a service road. Meanwhile, the other Tisons transferred their belongings into the Lyonses' car, keeping the Lyonses' money and guns. Gary Tison shot out the radiator on the Lincoln and forced the Lyonses out. John Lyons began begging Gary Tison for his life; Gary Tison remarked that he was "thinking about" killing the Lyonses. Gary told Raymond and Ricky to go back to the Lyonses' car and get some water. According to Raymond, while they were gone, Gary started shooting the Lyonses; according to Ricky, the shooting began once they returned with the water. The two agreed that they had returned in time to watch the elder Tison and Greenawalt kill the Lyonses. Their bodies were found five days later. Then, in Colorado, police believe