JUSTICE O'CONNOR, with whom JUSTICE WHITE joins, concurring in the result in part and dissenting in part.
I am in full agreement with JUSTICE REHNQUIST's conclusion that the Eighth Amendment does not create a substantive right not to be executed while insane. Accordingly, I do not join the Court's reasoning or opinion. Because, however, the conclusion is for me inescapable that Florida positive law has created a protected liberty interest in avoiding execution while incompetent, and because Florida does not provide even those minimal procedural protections required by due process in this area, I would vacate the judgment and remand to the Court of Appeals with directions that the case be returned to the Florida system so that a hearing can be held in a manner consistent with the requirements of the Due Process Clause. I cannot agree, however, that the federal courts should have any role whatever in the substantive determination of a defendant's competency to be executed.
As we explained in Hewitt v. Helms, 459 U. S. 460, 459 U. S. 466, (1983),
[l]iberty interests protected by the Fourteenth Amendment may arise from two sources -the Due Process Clause itself and the laws of the States.
See also Meachum v. Fano, 427 U. S. 215, 427 U. S. 223 -227 (1976). With JUSTICE REHNQUIST, I agree that the Due Process Clause does not independently create a protected interest in avoiding the execution of a death sentence during incompetency. See also Solesbee v. Balkcom, 339 U. S. 9 (1960). The relevant provision of the Florida statute, however, provides that the Governor " shall " have the prisoner committed to a "Department of Corrections mental health treatment facility" if the prisoner "does not have the mental capacity to understand the nature of the death penalty and why it was imposed on him." Fla.Stat. § 922.07(3) (1985 and Supp.1986). Our cases leave no doubt that, where a statute indicates with "language of an unmistakable mandatory character" that state conduct injurious to an individual will not occur "absent specified substantive predicates," the statute creates an expectation protected by the Due Process Clause. Hewitt v. Helms, supra, at 459 U. S. 471 -472. See also Vitek v. Jones, 445 U. S. 480, 445 U. S. 488 -491 (1980); Greenholtz v. Nebraska Penal Inmates, 442 U. S. 1, 442 U. S. 10 (1979) (entitlement created where under state law "there is [a] set of facts which, if shown, mandate a decision favorable to the individual"). That test is easily met here. Nor is it relevant that the statute creating the interest also specifies the procedures to be followed when the State seeks to deprive the individual of that interest. As we reaffirmed last Term, "[t]he categories of substance and procedure are distinct." Cleveland Board of Education v. Loudermill, 470 U. S. 532, 470 U. S. 541 (1985). Thus, regardless of the procedures the State deems adequate for determining the preconditions to adverse official action, federal law defines the kind of process a State must afford prior to depriving an individual of a protected liberty or property interest. Id. at 470 U. S. 541.
Although the state-created entitlement to avoid execution while insane unquestionably triggers the demands of the Due Process Clause, in my judgment those demands are minimal in this context. "It is axiomatic that due process is flexible, and calls for such procedural protections as the particular situation [requires].'" Greenholtz v. Nebraska Penal Inmates, supra, at 442 U. S. 12, quoting Morrissey v. Brewer, 408 U. S. 471, 408 U. S. 481 (1972). And there are any number of reasons for concluding that this "particular situation" warrants substantial caution before reading the Due Process Clause to mandate anything like the full panoply of trial-type procedures. The prisoner's interest in avoiding an erroneous determination is, of course, very great. But I consider it self-evident that, once society has validly convicted an individual of a crime and therefore established its right to punish, the demands of due process are reduced accordingly. Meachum v. Fano, supra, at 427 U. S. 224. Moreover, the potential for false claims and deliberate delay in this context is obviously enormous. Nobles v. Georgia, 168 U. S. 398, 168 U. S. 405 -406 (1897). This potential is exacerbated by a unique feature of the prisoner's protected interest in suspending the execution of a death sentence during incompetency. By definition, this interest can never be conclusively and finally determined: regardless of the number of prior adjudications of the issue, until the very moment of execution, the prisoner can claim that he has become insane sometime after the previous determination to the contrary. Hazard & Louisell, Death, the State and the Insane: Stay of Execution, 9 UCLA L.Rev. 381, 399-400 (1962). These difficulties, together with the fact that the issue arises only after conviction and sentencing, convince me that the Due Process Clause imposes few requirements on the States in this context.
Even given the broad latitude I would leave to the States in this area, however, I believe that one aspect of the Florida procedure for determining competency to be executed renders that procedure constitutionally deficient. If there is one "fundamental requisite" of due process, it is that an individual is entitled to an "opportunity to be heard." Grannis v. Ordean, 234 U. S. 385, 284 U. S. 394 (1914). As currently implemented, the Florida procedure for determining competency violates this bedrock principle. By Executive Order, the present Governor has provided that
[c]ounsel for the inmate and the State Attorney may be present [at the competency hearing] but shall not participate in the examination in any adversarial manner.
Exec.Order No. 83-137 (Dec. 9, 1983). See also Goode v. Wainwright, 448 So.2d 999, 1001 (Fla.1984) (describing the Governor's "publicly announced policy of excluding all advocacy on the part of the condemned from the process of determining whether a person under a sentence of death is insane"). Indeed, respondent does not dispute that the Governor's office has steadfastly refused to acknowledge whether it would even review the extensive psychiatric materials submitted by petitioner concerning his present mental state. While I would not invariably require oral advocacy or even cross-examination, due process at the very least requires that the decisionmaker consider the prisoner's written submissions.
I conclude therefore that Florida law has created a protected expectation that no execution will be carried out while the prisoner lacks the "mental capacity to understand the nature of the death penalty and why it was imposed on him." Fla.Stat. § 922.07(3) (1985). Because Florida's procedures are inadequate to satisfy even the minimal requirements of due process in this context, I would vacate the judgment below with instructions that the case be returned to Florida so that it might assess petitioner's competency in a manner that accords with the command of the Fourteenth Amendment. In my view, however, the only federal question presented in cases such as this is whether the State's positive law has created a liberty interest and whether its procedures are adequate to protect that interest from arbitrary deprivation. Once satisfied that the procedures were adequate, a federal court has no authority to second-guess a State's substantive competency determination.