A defendant has the right to a competency evaluation before being executed. Decided June 26, 1986 (argued April 22, 1986). Opinion of the Court: Marshall (parts I and II) Dissenting: Rehnquist. Applied: the Eighth Amendment → go there Applied: the Fourteenth Amendment → go there Topic: Competence. Ford v. Wainwright, 477 U.S. 399 (1986), is a landmark U.S. Supreme Court case that upheld the common law rule that the insane cannot be executed; therefore the petitioner is entitled to a competency evaluation and to an evidentiary hearing in court on the question of their competency to be executed. Wiki link