The United States Supreme Court has concluded that the death penalty serves two important purposes: retribution and deterrence of capital crimes by prospective offenders. See Gregg v. Georgia, 428 U.S. 153, 183-86, 49 L. Ed. 2d 859, 96 S. Ct. 2909 (1976) (plurality opinion). "A state can only execute a condemned prisoner if it contributes to these two purposes." aff'd, 891 F.2d 807 (11th Cir. 1989). In Ford v. Wainwright, 477 U.S. 399, 410, 91 L. Ed. 2d 335, 106 S. Ct. 2595 (1986), the Supreme Court held that the execution of a defendant who becomes incompetent after conviction is prohibited by the Eighth Amendment of the United States Constitution. The Court did not set forth the standard for determining incompetency. However, Justice Powell, in his concurring opinion, did provide guidance: Florida requires the Governor to stay executions of those who "do not have the mental capacity to understand the nature of the death penalty and why it was imposed" on them. A number of States have more rigorous standards, but none disputes the need to require that those who are executed know the fact of their impending execution and the reason for it. Such a standard appropriately defines the kind of mental deficiency that should trigger the Eighth Amendment prohibition. If the defendant perceives the connection between his crime and his punishment, the retributive goal of the criminal law is satisfied. And only if the defendant is aware that his death is approaching can he prepare himself for his passing. Accordingly, I would hold that the Eighth Amendment forbids the execution only of those who are unaware of the punishment they are about to suffer and why they are to suffer it. 477 U.S. at 421-22 (Powell, J., concurring).