concurring in part and concurring in the judgment.
I join Parts I and II of the Court’s opinion. As Justice Marshall ably demonstrates, execution of the insane was barred at common law precisely because it was considered cruel and unusual. In Solem v. Helm, 463 U. S. 277 (1983), we explained that while the Framers “may have intended the Eighth Amendment to go beyond the scope of its English counterpart, their use of the language of the English Bill of Rights is convincing proof that they intended to provide at least the same protection.” Id., at 286. It follows that the practice of executing the insane is barred by our own Constitution.
That conclusion leaves two issues for our determination: (i) the meaning of insanity in this context, and (ii) the procedures States must follow in order to avoid the necessity of de novo review in federal courts under 28 U. S. C. § 2254(d). The Court’s opinion does not address the first of these issues, and as to the second, my views differ substantially from Justice Marshall’s. I therefore write separately.
*419I
The Court holds today that the Eighth Amendment bars execution of a category of defendants defined by their mental state. The bounds of that category are necessarily governed by federal constitutional law. I therefore turn to the same sources that give rise to the substantive right to determine its precise definition: chiefly, our common-law heritage and the modern practices of the States, which are indicative of our “evolving standards of decency.” Trop v. Dulles, 356 U. S. 86, 101 (1958) (plurality opinion). See Solem v. Helm, supra, at 284-286; Gregg v. Georgia, 428 U. S. 153, 175-176 (1976) (opinion of Stewart, Powell, and Stevens, JJ.).
A
As the Court recognizes, ante, at 407-408, the ancient prohibition on execution of the insane rested on differing theories. Those theories do not provide a common answer when it comes to defining the mental awareness required by the Eighth Amendment as a prerequisite to a defendant’s execution. On the one hand, some authorities contended that the prohibition against executing the insane was justified as a way of preserving the defendant’s ability to make arguments on his own behalf. See 1 M. Hale, Pleas of the Crown 35 (1736) (“if after judgment he become of non sane memory, his execution shall be spared; for were he of sound memory he might allege somewhat in stay of judgment or execution”); accord 4 W. Blackstone, Commentaries *388-*389. Other authorities suggest, however, that the prohibition derives from more straightforward humanitarian concerns. Coke expressed the view that execution was intended to be an “example” to the living, but that the execution of “a mad man” was such “a miserable spectacle ... of extream inhumanity and cruelty” that it “can be no example to others.” 3 E. Coke, Institutes 6 (1794). Hawles added that it is “against Christian charity to send a great offender quick . . . into another world, when he is not of a capacity to fit himself for it.” *420Hawles, Remarks on the Trial of Mr. Charles Bateman, 11 How. St. Tr. 474, 477 (1685).
The first of these justifications has slight merit today. Modern practice provides far more extensive review of convictions and sentences than did the common law, including not only direct appeal but ordinarily both state and federal collateral review.1 Throughout this process, the defendant has access to counsel, by constitutional right at trial, and by employment or appointment at other stages of the process whenever the defendant raises substantial claims. Nor does the defendant merely have the right to counsel’s assistance; he also has the right to the effective assistance of counsel at trial and on appeal. Evitts v. Lucey, 469 U. S. 387 (1985); Strickland v. Washington, 466 U. S. 668 (1984). See Kimmelman v. Morrison, ante, at 392-393 (Powell, J., concurring in judgment). These guarantees are far broader than those enjoyed by criminal defendants at common law. It is thus unlikely indeed that a defendant today could go to his death with knowledge of undiscovered trial error that might set him free.
In addition, in cases tried at common law execution often followed fairly quickly after trial, so that incompetence at the *421time of execution was linked as a practical matter with incompetence at the trial itself. Our decisions already recognize, however, that a defendant must be competent to stand trial, and thus the notion that a defendant must be able to assist in his defense is largely provided for. See Drope v. Missouri, 420 U. S. 162 (1975).2
B
The more general concern of the common law — that executions of the insane are simply cruel — retains its vitality. It is as true today as when Coke lived that most men and women value the opportunity to prepare, mentally and spiritually, for their death. Moreover, today as at common law, one of the death penalty’s critical justifications, its retributive force, depends on the defendant’s awareness of the penalty’s existence and purpose. Thus, it remains true that executions of the insane both impose a uniquely cruel penalty and are inconsistent with one of the chief purposes of executions generally. For precisely these reasons, Florida requires the Governor to stay executions of those who “d[o] not have the mental capacity to understand the nature of the death penalty and why it was imposed” on them. Fla. Stat. §922.07 (1985 and Supp. 1986). See also Ill. Rev. Stat., ch. 38, ¶ 1005-2-3(a) (1985) (“A person is unfit to be executed if because of a mental condition he is unable to understand the nature and purpose of such sentence”); State v. Pastet, 169 Conn. 13, 28, 363 A. 2d 41, 49 (question is “whether the defendant was able to understand the nature of the sentencing proceedings, i. e., why he was being punished and the nature of his punishment”), cert, denied, 423 U. S. 937 (1975). A number of *422States have more rigorous standards,3 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.
Petitioner’s claim of insanity plainly fits within this standard. According to petitioner’s proffered psychiatric examination, petitioner does not know that he is to be executed, but rather believes that the death penalty has been invalidated. App. 65-67. If this assessment is correct, petitioner *423cannot connect his execution to the crime for which he was convicted. Thus, the question is whether petitioner’s evidence entitles him to a hearing in Federal District Court on his claim.
II
Petitioner concedes that the Governor of Florida has determined that he is not insane under the standard prescribed by Florida’s statute, which is the same as the standard just described. Petitioner further concedes that there is expert evidence that supports the Governor’s finding. Thus, if that finding is entitled to a presumption of correctness under 28 U. S. C. § 2254(d), there is no ground for holding a hearing on petitioner’s federal habeas corpus petition.
I agree with Justice Marshall that the Governor’s finding is not entitled to a presumption of correctness under § 2254(d). I reach this conclusion for two independent reasons. First, § 2254(d) requires deference to the factual findings of “a State court of competent jurisdiction.” The term “State court” may have a certain amount of flexibility,4 but no amount of stretching can extend it to include the Governor. The essence of a “court” is independence from the prosecutorial arm of government and, as Justice Marshall correctly notes, the Governor is “[t]he commander of the State’s corps of prosecutors.” Ante, at 416. Unless the relevant language is to be read out of the statute, I see no basis for affording any deference to the Governor’s determination.
Second, the presumption of correctness does not attach to the Governor’s implicit finding of sanity because the State did not give petitioner’s claim “a full and fair hearing,” 28 U. S. C. § 2254(d)(2). This statutory phrase apparently was drawn from the Court’s opinion in Townsend v. Sain, 372 U. S. 293, 313 (1963). There, the Court concluded that where the state court’s “fact-finding procedure . . . was not *424adequate for reaching reasonably correct results,” or where the process “appeared] to be seriously inadequate for the ascertainment of the truth,” no presumption of correctness would attach to the state court’s findings when those findings were challenged on federal habeas corpus. Id., at 316.
At least in the context of competency determinations prior to execution, this standard is no different from the protection afforded by procedural due process. It is clear that an insane defendant’s Eighth Amendment interest in forestalling his execution unless or until he recovers his sanity cannot be deprived without a “fair hearing.” Indeed, fundamental fairness is the hallmark of the procedural protections afforded by the Due Process Clause. See Lassiter v. Department of Social Services of Durham County, 452 U. S. 18, 24-25 (1981). Thus, the question in this case is whether Florida’s procedures for determining petitioner’s sanity comport with the requirements of due process.
Together with Justice Marshall and Justice O’Con-nor, I would hold that they do not. As Justice O’Connor states, “[i]f there is one ‘fundamental requisite’ of due process, it is that an individual is entitled to an ‘opportunity to be heard.’” Post, at 430 (quoting Grannis v. Ordean, 234 U. S. 385, 394 (1914)). In this case, petitioner was deprived of that opportunity. The Florida statute does not require the Governor to consider materials submitted by the prisoner, and the present Governor has a “publicly announced policy of excluding” such materials from his consideration. Goode v. Wainwright, 448 So. 2d 999, 1001 (Fla. 1984). Thus, the determination of petitioner’s sanity appears to have been made solely on the basis of the examinations performed by state-appointed psychiatrists. Such a procedure invites arbitrariness and error by preventing the affected parties from offering contrary medical evidence or even from explaining the inadequacies of the State’s examinations. It does not, therefore, comport with due process. It follows that the State’s procedure was not “fair,” and that the Dis*425trict Court on remand must consider the question of petitioner’s competency to be executed.
I — H I — I I — I
While the procedures followed by Florida in this case do not comport with basic fairness, I would not require the kind of full-scale “sanity trial” that Justice Marshall appears to find necessary. See ante, at 413-416, 418. Due process is a flexible concept, requiring only “such procedural protections as the particular situation demands.” Mathews v. Eldridge, 424 U. S. 319, 334 (1976); Morrissey v. Brewer, 408 U. S. 471, 481 (1972). See also post, at 429 (O’Connor, J., concurring in result in part and dissenting in part). In this instance, a number of considerations support the conclusion that the requirements of due process are not as elaborate as Justice Marshall suggests.
First, the Eighth Amendment claim at issue can arise only after the prisoner has been validly convicted of a capital crime and sentenced to death. Thus, in this case the State has a substantial and legitimate interest in taking petitioner’s life as punishment for his crime. That interest is not called into question by petitioner’s claim. Rather, the only question raised is not whether, but when, his execution may take place.5 This question is important, but it is not comparable to the antecedent question whether petitioner should be executed at all. It follows that this Court’s decisions imposing heightened procedural requirements on capital trials and sentencing proceedings — e. g., Lockett v. Ohio, 438 U. S. 586 (1978) (plurality opinion); Turner v. Murray, 476 U. S. 28 (1986) — do not apply in this context.
Second, petitioner does not make his claim of insanity against a neutral background. On the contrary, in order to *426have been convicted and sentenced, petitioner must have been judged competent to stand trial, or his competency-must have been sufficiently clear as not to raise a serious question for the trial court. The State therefore may properly presume that petitioner remains sane at the time sentence is to be carried out,6 and may require a substantial threshold showing of insanity merely to trigger the hearing process. Cf. Ake v. Oklahoma, 470 U. S. 68, 82-83 (1985).
Finally, the sanity issue in this type of case does not resemble the basic issues at trial or sentencing. Unlike issues of historical fact, the question of petitioner’s sanity calls for a basically subjective judgment. See Addington v. Texas, 441 U. S. 418, 429-430 (1979); cf. Barefoot v. Estelle, 463 U. S. 880, 898-901 (1983). And unlike the determination of whether the death penalty is appropriate in a particular case, the competency determination depends substantially on expert analysis in a discipline fraught with “subtleties and nuances.” Addington, supra, at 430. This combination of factors means that ordinary adversarial procedures — complete with live testimony, cross-examination, and oral argument by counsel — are not necessarily the best means of arriving at sound, consistent judgments as to a defendant’s sanity. Cf. Parham v. J. R., 442 U. S. 584, 609 (1979) (“Common human experience and scholarly opinions suggest that the supposed protections of an adversary proceeding to determine the appropriateness of medical decisions for the commitment and treatment of mental and emotional illness may well be more illusory than real”).
*427We need not determine the precise limits that due process imposes in this area. In general, however, my view is that a constitutionally acceptable procedure may be far less formal than a trial. The State should provide an impartial officer or board that can receive evidence and argument from the prisoner’s counsel, including expert psychiatric evidence that may differ from the State’s own psychiatric examination. Beyond these basic requirements, the States should have substantial leeway to determine what process best balances the various interests at stake. As long as basic fairness is observed, I would find due process satisfied, and would apply the presumption of correctness of § 2254(d) on federal habeas corpus.
> HH
Because petitioner has raised a viable claim under the Eighth Amendment, and because that claim was not adjudicated fairly within the meaning of due process or of § 2254(d), petitioner is entitled to have his claim adjudicated by the District Court on federal habeas corpus. I therefore join the Court’s judgment.
Petitioner offers a good example. Petitioner was convicted of first-degree murder in 1974. On direct appeal, his conviction and sentence were affirmed, Ford v. State, 374 So. 2d 496 (Fla. 1979), and this Court denied certiorari. 445 U. S. 972 (1980). Petitioner then joined 122 other death row inmates in seeking extraordinary relief from the Florida Supreme Court, based on that court’s allegedly improper procedure for review of capital cases. This petition for relief was denied, Brown v. Wainwright, 392 So. 2d 1327 (Fla. 1981), and this Court again denied certiorari. 454 U. S. 1000 (1981). Petitioner filed a motion for postconviction relief in state court, and relief was again denied. Ford v. State, 407 So. 2d 907 (Fla. 1981). Following these unsuccessful attempts to obtain relief from his conviction or execution in state court, petitioner filed a petition for ha-beas corpus in federal court. Relief was again denied, Ford v. Strickland, 696 F. 2d 804 (CA11) (en banc), cert, denied, 464 U. S. 865 (1983). Only after all of these challenges had been resolved against him did petitioner challenge his impending execution on the ground of insanity.
Moreover, a standard that focused on the defendant’s ability to assist in his defense would give too little weight to the State’s interest in finality, since it implies a constitutional right to raise new challenges to one’s criminal conviction until sentence has run its course. Such an implication is false: we have made clear that States have a strong and legitimate interest in avoiding repetitive collateral review through procedural bars. See Kuhlmann v. Wilson, post, at 452-454 (plurality opinion).
A number of States have remained faithful to Blackstone’s view that a defendant cannot be executed unless he is able to assist in his own defense. E.g., Miss. Code Ann. § 99-19-57(2)(b) (Supp. 1985); Mo. Rev. Stat. § 552.060(1) (1978); Utah Code Ann. § 77-15-2 (1982). The majority of States appear not to have addressed the issue in their statutes. Modern case authority on this question is sparse, and while some older cases favor the Blaekstone view, see 24 C. J. S., Criminal Law §1619 (1961), those cases largely antedate the recent expansion of both the right to counsel and the availability of federal and state collateral review. Moreover, other eases suggest that the prevailing test is “whether the condemned man was aware of his conviction and the nature of his impending fate” — essentially the same test stated by Florida’s statute. Note, Insanity of the Condemned, 88 Yale L. J. 533, 540 (1979); see Hazard & Louisell, Death, the State, and the Insane: Stay of Execution, 9 UCLA L. Rev. 381, 394, and n. 44 (1962) (discussing eases). Under these circumstances, I find no sound basis for constitutionalizing the broader definition of insanity, with its requirement that the defendant be able to assist in his own defense. States are obviously free to adopt a more expansive view of sanity in this context than the one the Eighth Amendment imposes as a constitutional minimum.
Although we need not decide the issue in this case, the term “State court” may well encompass an independent panel of psychiatric experts who might both examine the defendant and determine his legal sanity.
It is of course true that some defendants may lose their mental faculties and never regain them, and thus avoid execution altogether. My point is only that if petitioner is cured of his disease, the State is free to execute him.
Cf. Addington v. Texas, 441 U. S. 418 (1979). In Addington, the Court held that States must require proof by clear and convincing evidence in order to involuntarily commit an individual to a mental hospital for treatment. In this context, it is the defendant and not the State who seeks to overcome the presumption that he is sane; moreover, he does so following a trial and sentencing at which his sanity was either conceded or determined by the court.