Justice Powell
delivered the opinion of the Court.
The question presented is whether petitioner, who was committed to a mental hospital upon being acquitted of a criminal offense by reason of insanity, must be released because he has been hospitalized for a period longer than he might have served in prison had he been convicted.
In the District of Columbia a criminal defendant may be acquitted by reason of insanity if his insanity is “affirmatively established by a preponderance of the evidence.” D. C. Code § 24 — 801(j) (1981). If he successfully invokes the insanity defense, he is committed to a mental hospital. §24-301(d)(l). The statute provides several ways of obtaining release. Within 50 days of commitment the acquittee is entitled to a judicial hearing to determine his eligibility for release, at which he has the burden of proving by a preponderance of the evidence that he is no longer mentally ill or dangerous. § 24 — 301(d)(2). If he fails to meet this burden at the 50-day hearing, the committed acquittee subsequently may be released, with court approval, upon certification of his recovery by the hospital chief of service. §24-301(e). Alternatively, the acquittee is entitled to a judicial hearing every six months at which he may establish by a preponderance of the evidence that he is entitled to release. §24-301(k).
Independent of its provision for the commitment of insanity acquittees, the District of Columbia also has adopted a civil-commitment procedure, under which an individual may be committed upon clear and convincing proof by the Government that he is mentally ill and likely to injure himself or others. § 21-545(b). The individual may demand a jury in the civil-commitment proceeding. § 21-544. Once committed, a patient may be released at any time upon certification of recovery by the hospital chief of service. §§ 21-546, 21-548. Alternatively, the patient is entitled after the first 90 days, and subsequently at 6-month intervals, to request a judicial hearing at which he may gain his release by proving by a preponderance of the evidence that he is no longer mentally ill or dangerous. §§21-546, 21-547; see Dixon v. Jacobs, 138 U. S. App. D. C. 319, 328, 427 F. 2d 589, 598 (1970).
H-Í
On September 19, 1975, petitioner was arrested for attempting to steal a jacket from a department store. The next day he was arraigned in the District of Columbia Superior Court on a charge of attempted petit larceny, a misdemeanor punishable by a maximum prison sentence of one year. §§22-103, 22-2202. The court ordered petitioner committed to St. Elizabeths, a public hospital for the mentally ill, for a determination of his competency to stand trial. On March 1, 1976, a hospital psychologist submitted a report to the court stating that petitioner was competent to stand trial, that petitioner suffered from “Schizophrenia, paranoid type,” and that petitioner’s alleged offense was “the product of his mental disease.” Record 51. The court ruled that petitioner was competent to stand trial. Petitioner subsequently decided to plead not guilty by reason of insanity. The Government did not contest the plea, and it entered into a stipulation of facts with petitioner. On March 12,1976, the Superior Court found petitioner not guilty by reason of insanity and committed him to St. Elizabeths pursuant to § 24-301(d)(l).
On May 25, 1976, the court held the 50-day hearing required by § 24-301(d)(2)(A). A psychologist from St. Eliza-beths testified on behalf of the Government that, in the opinion of the staff, petitioner continued to suffer from paranoid schizophrenia and that “because his illness is still quite active, he is still a danger to himself and to others.” Tr. 9. Petitioner’s counsel conducted a brief cross-examination, and presented no evidence. The court then found that “the defendant-patient is mentally ill and as a result of his mental illness, at this time, he constitutes a danger to himself or others.” Id., at 13. Petitioner was returned to St. Elizabeths. Petitioner obtained new counsel and, following some procedural confusion, a second release hearing was held on February 22, 1977. By that date petitioner had been hospitalized for more than one year, the maximum period he could have spent in prison if he had been convicted. On that basis he demanded that he be released unconditionally or recommitted pursuant to the civil-commitment standards in § 21— 545(b), including a jury trial and proof by clear and convincing evidence of his mental illness and dangerousness. The Superior Court denied petitioner’s request for a civil-commitment hearing, reaffirmed the findings made at the May 25, 1976, hearing, and continued petitioner’s commitment to St. Elizabeths.
Petitioner appealed to the District of Columbia Court of Appeals. A panel of the court affirmed the Superior Court, 396 A. 2d 183 (1978), but then granted rehearing and reversed, 411 A. 2d 624 (1980). Finally, the court heard the case en banc and affirmed the judgment of the Superior Court. 432 A. 2d 364 (1981). The Court of Appeals rejected the argument “that the length of the prison sentence [petitioner] might have received determines when he is entitled to release or civil commitment under Title 24 of the D. C. Code.” Id., at 368. It then held that the various statutory differences between civil commitment and commitment of insanity acquittees were justified under the equal protection component of the Fifth Amendment. Id., at 371-376.
We granted certiorari, 454 U. S. 1141 (1982), and now affirm.
Ill
It is clear that “commitment for any purpose constitutes a significant deprivation of liberty that requires due process protection.” Addington v. Texas, 441 U. S. 418, 425 (1979). Therefore, a State must have “a constitutionally adequate purpose for the confinement.” O’Connor v. Donaldson, 422 U. S. 563, 574 (1975). Congress has determined that a criminal defendant found not guilty by reason of insanity in the District of Columbia should be committed indefinitely to a mental institution for treatment and the protection of society. See H. R. Rep. No. 91-907, pp. 73-74 (1970); 432 A. 2d, at 371 (“[T]he District of Columbia statutory scheme for commitment of insane criminals is ... a regulatory, prophylactic statute, based on a legitimate governmental interest in protecting society and rehabilitating mental patients”). Petitioner does not contest the Government’s authority to commit a mentally ill and dangerous person indefinitely to a mental institution, but rather contends that “the petitioner’s trial was not a constitutionally adequate hearing to justify an indefinite commitment.” Brief for Petitioner 14.
Petitioner’s argument rests principally on Addington v. Texas, supra, in which the Court held that the Due Process Clause requires the State in a civil-commitment proceeding to demonstrate by clear and convincing evidence that the individual is mentally ill and dangerous. 441 U. S., at 426-427. Petitioner contends that these due process standards were not met in his case because the judgment of not guilty by reason of insanity did not constitute a finding of present mental illness and dangerousness and because it was established only by a preponderance of the evidence. Petitioner then concludes that the Government’s only conceivably legitimate justification for automatic commitment is to ensure that insanity acquittees do not escape confinement entirely, and that this interest can justify commitment at most for a period equal to the maximum prison sentence the acquit-tee could have received if convicted. Because petitioner has been hospitalized for longer than the one year he might have served in prison, he asserts that he should be released unconditionally or recommitted under the District’s civil-commitment procedures.
A
. We turn first to the question whether the finding of insanity at the criminal trial is sufficiently probative of mental illness and dangerousness to justify commitment. A verdict of not guilty by reason of insanity establishes two facts: (i) the defendant committed an act that constitutes a criminal offense, and (ii) he committed the act because of mental illness. Congress has determined that these findings constitute an adequate basis for hospitalizing the acquittee as a dangerous and mentally ill person. See H. R. Rep. No. 91-907, supra, at 74 (expressing fear that “dangerous criminals, particularly psychopaths, [may] win acquittals of serious criminal charges on grounds of insanity” and yet “escape hospital commitment”); S. Rep. No. 1170, 84th Cong., 1st Sess., 13 (1955) (“Where [the] accused has pleaded insanity as a defense to a crime, and the jury has found that the defendant was, in fact, insane at the time the crime was committed, it is just and reasonable in the Committee’s opinion that the insanity, once established, should be presumed to continue and that the accused should automatically be confined for treatment until it can be shown that he has recovered”). We cannot say that it was unreasonable and therefore unconstitutional for Congress to make this determination.
The fact that a person has been found, beyond a reasonable doubt, to have committed a criminal act certainly indicates dangerousness. See Lynch v. Overholser, 369 U. S. 705, 714 (1962) (The fact that the accused was found to have committed a criminal act is “strong evidence that his continued liberty could imperil ‘the preservation of public peace’ ”). Indeed, this concrete evidence generally may be at least as persuasive as any predictions about dangerousness that might be made in a civil-commitment proceeding. We do not agree with petitioner’s suggestion that the requisite dangerousness is not established by proof that a person committed a nonviolent crime against property. This Court never has held that “violence,” however that term might be defined, is a prerequisite for a constitutional commitment.
Nor can we say that it was unreasonable for Congress to determine that the insanity acquittal supports an inference of continuing mental illness. It comports with common sense to conclude that someone whose mental illness was sufficient to lead him to commit a criminal act is likely to remain ill and in need of treatment. The precise evidentiary force of the insanity acquittal, of course, may vary from case to case, but the Due Process Clause does not require Congress to make classifications that fit every individual with the same degree of relevance. See Marshall v. United States, 414 U. S. 417, 428 (1974). Because a hearing is provided within 50 days of the commitment, there is assurance that every acquittee has prompt opportunity to obtain release if he has recovered.
Petitioner also argues that, whatever the evidentiary value of the insanity acquittal, the Government lacks a legitimate reason for committing insanity acquittees automatically because it can introduce the insanity acquittal as evidence in a subsequent civil proceeding. This argument fails to consider the Government’s strong interest in avoiding the need to conduct a de novo commitment hearing following every insanity acquittal — a hearing at which a jury trial may be demanded, § 21-544, and at which the Government bears the burden of proof by clear and convincing evidence. Instead of focusing on the critical question whether the acquittee has recovered, the new proceeding likely would have to relitigate much of the criminal trial. These problems accent the Government’s important interest in automatic commitment. See Mathews v. Eldridge, 424 U. S. 319, 348 (1976). We therefore conclude that a finding of not guilty by reason of insanity is a sufficient foundation for commitment of an insanity acquittee for the purposes of treatment and the protection of society.
B
Petitioner next contends that his indefinite commitment is unconstitutional because the proof of his insanity was based only on a preponderance of the evidence, as compared to Addington’s civil-commitment requirement of proof by clear and convincing evidence. In equating these situations, petitioner ignores important differences between the class of potential civil-commitment candidates and the class of insanity acquittees that justify differing standards of proof. The Addington Court expressed particular concern that members of the public could be confined on the basis of “some abnormal behavior which might be perceived by some as symptomatic of a mental or emotional disorder, but which is in fact within a range of conduct that is generally acceptable.” 441 U. S., at 426-427. See also O’Connor v. Donaldson, 422 U. S., at 575. In view of this concern, the Court deemed it inappropriate to ask the individual “to share equally with society the risk of error.” Addington, 441 U. S., at 427. But since automatic commitment under § 24-301(d)(1) follows only if the acquittee himself advances insanity as a defense and proves that his criminal act was a product of his mental illness, there is good reason for diminished concern as to the risk of error. More important, the proof that he committed a criminal act as a result of mental illness eliminates the risk that he is being committed for mere “idiosyncratic behavior,” Addington, 441 U. S., at 427. A criminal act by definition is not “within a range of conduct that is generally acceptable.” Id., at 426-427.
We therefore conclude that concerns critical to our decision in Addington are diminished or absent in the case of insanity acquittees. Accordingly, there is no reason for adopting the same standard of proof in both cases. “[D]ue process is flexible and calls for such procedural protections as the particular situation demands.” Morrissey v. Brewer, 408 U. S. 471, 481 (1972). The preponderance of the evidence standard comports with due process for commitment of insanity acquittees.
C
The remaining question is whether petitioner nonetheless is entitled to his release because he has been hospitalized for a period longer than he could have been incarcerated if convicted. The Due Process Clause “requires that the nature and duration of commitment bear some reasonable relation to the purpose for which the individual is committed. ” Jackson v. Indiana, 406 U. S. 715, 738 (1972). The purpose of commitment following an insanity acquittal, like that of civil commitment, is to treat the individual’s mental illness and protect him and society from his potential dangerousness. The committed acquittee is entitled to release when he has recovered his sanity or is no longer dangerous. See O’Connor v. Donaldson, supra, at 575-576; 432 A. 2d, at 372, and n. 16; H. R. Rep. No. 91-907, pp. 73-74 (1970). And because it is impossible to predict how long it will take for any given individual to recover — or indeed whether he ever will recover — Congress has chosen, as it has with respect to civil commitment, to leave the length of commitment indeterminate, subject to periodic review of the patient’s suitability for release.
In light of the congressional purposes underlying commitment of insanity acquittees, we think petitioner clearly errs in contending that an acquittee’s hypothetical maximum sentence provides the constitutional limit for his commitment. A particular sentence of incarceration is chosen to reflect society’s view of the proper response to commission of a particular criminal offense, based on a variety of considerations such as retribution, deterrence, and rehabilitation. See, e. g., Gregg v. Georgia, 428 U. S. 153, 183-186 (1976) (opinion of Stewart, Powell, and Stevens, JJ.); Kennedy v. Mendoza-Martinez, 372 U. S. 144, 168 (1963); Williams v. New York, 337 U. S. 241, 248-249 (1949). The State may punish a person convicted of a crime even if satisfied that he is unlikely to commit further crimes.
Different considerations underlie commitment of an insanity acquittee. As he was not convicted, he may not be punished. His confinement rests on his continuing illness and dangerousness. Thus, under the District of Columbia statute, no matter how serious the act committed by the acquit-tee, he may be released within 50 days of his acquittal if he has recovered. In contrast, one who committed a less serious act may be confined for a longer period if he remains ill and dangerous. There simply is no necessary correlation between severity of the offense and length of time necessary for recovery. The length of the acquittee’s hypothetical criminal sentence therefore is irrelevant to the purposes of his commitment.
<3
We hold that when a criminal defendant establishes by a preponderance of the evidence that he is not guilty of a crime by reason of insanity, the Constitution permits the Government, on the basis of the insanity judgment, to confine him to a mental institution until such time as he has regained his sanity or is no longer a danger to himself or society. This holding accords with the widely and reasonably held view that insanity acquittees constitute a special class that should be treated differently from other candidates for commitment. We have observed before that “[w]hen Congress undertakes to act in areas fraught with medical and scientific uncertainties, legislative options must be especially broad and courts should be cautious not to rewrite legislation . . . .” Marshall v. United States, 414 U. S., at 427. This admonition has particular force in the context of legislative efforts to deal with the special problems raised by the insanity defense.
The judgment of the District of Columbia Court of Appeals is
Affirmed.
Section 24-301(j) provides:
“Insanity shall not be a defense in any criminal proceeding in the United States District Court for the District of Columbia or in the Superior Court of the District of Columbia, unless the accused or his attorney in such proceeding, at the time the accused enters his plea of not guilty or within 15 days thereafter or at such later time as the court may for good cause permit, files with the court and serves upon the prosecuting attorney written notice of his intention to rely on such defense. No person accused of an offense shall be acquitted on the ground that he was insane at the time of its commission unless his insanity, regardless of who raises the issue, is affirmatively established by a preponderance of the evidence.”
Section 24-301(d)(l) provides:
“If any person tried upon an indictment or information for an offense raises the defense of insanity and is acquitted solely on the ground that he was insane at the time of its commission, he shall be committed to a hospital for the mentally ill until such time as he is eligible for release pursuant to this subsection or subsection (e) of this section.”
Under this provision, automatic commitment is permissible only if the defendant himself raised the insanity defense. See H. R. Rep. No. 91-907, p. 74 (1970); Lynch v. Overholser, 369 U. S. 705 (1962).
Section 24-301(d)(2) provides in relevant part:
“(A) A person confined pursuant to paragraph (1) of this subsection shall have a hearing, unless waived, within 50 days of his confinement to determine whether he is entitled to release from custody. . . .
“(B) If the hearing is not waived, the court shall cause notice of the hearing to be served upon the person, his counsel, and the prosecuting attorney and hold the hearing. Within 10 days from the date the hearing was begun, the court shall determine the issues and make findings of fact and conclusions of law with respect thereto. The person confined shall have the burden of proof. If the court finds by a preponderance of the evidence that the person confined is entitled to his release from custody, either conditional or unconditional, the court shall enter such order as may appear appropriate.”
The statute does not specify the standard for determining release, but the District of Columbia Court of Appeals held in this case that, as in release proceedings under § 24-301(e) and § 21-545(b), the confined person must show that he is either no longer mentally ill or no longer dangerous to himself or others. See 432 A. 2d 364, 372, and n. 16 (1981) (en banc).
Section 24-301(e) provides in relevant part:
“Where any person has been confined in a hospital for the mentally ill pursuant to subsection (d) of this section, and the superintendent of such hospital certifies: (1) That such person has recovered his sanity; (2) that, in the opinion of the superintendent, such person will not in the reasonable future be dangerous to himself or others; and (3) in the opinion of the superintendent, the person is entitled to his unconditional release from the hospital, and such certificate is filed with the clerk of the court in which the person was tried, and a copy thereof served on the United States Attorney or the Corporation Counsel of the District of Columbia, whichever office prosecuted the accused, such certificate shall be sufficient to authorize the court to order the unconditional release of the person so confined from further hospitalization at the expiration of 15 days from the time said certificate was filed and served as above; but the court in its discretion may, or upon objection of the United States or the District of Columbia shall, after due notice, hold a hearing at which evidence as to the mental condition of the person so confined may be submitted, including the testimony of 1 or more psychiatrists from said hospital. The court shall weigh the evidence and, if the court finds that such person has recovered his sanity and will not in the reasonable future be dangerous to himself or others, the court shall order such person unconditionally released from further confinement in said hospital. If the court does not so find, the court shall order such person returned to said hospital. ...”
Section 24-301(k) provides in relevant part:
“(1) A person in custody or conditionally released from custody, pursuant to the provisions of this section, claiming the right to be released from custody, the right to any change in the conditions of his release, or other relief concerning his custody, may move the court having jurisdiction to order his release, to release him from custody, to change the conditions of his release, or to grant other relief.
“(3) ... On all issues raised by his motion, the person shall have the burden of proof. If the court finds by a preponderance of the evidence that the person is entitled to his release from custody, either conditional or unconditional, a change in the conditions of his release, or other relief, the court shall enter such order as may appear appropriate.
“(5) A court shall not be required to entertain a 2nd or successive motion for relief under this section more often than once every 6 months. A court for good cause shown may in its discretion entertain such a motion more often than once every 6 months.”
Section 21-545(b) provides in relevant part:
“If the court or jury finds that the person is mentally ill and, because of that illness, is likely to injure himself or other persons if allowed to remain at liberty, the court may order his hospitalization for an indeterminate period, or order any other alternative course of treatment which the court believes will be in the best interests of the person or of the public.” See In re Nelson, 408 A. 2d 1233 (D. C. 1979) (reading into the statute the due process requirement of “clear and convincing” proof).
Section 24-301(a) authorizes the court to “order the accused committed to the District of Columbia General Hospital or other mental hospital designated by the court, for such reasonable period as the court may determine for examination and observation and for care and treatment if such is necessary by the psychiatric staff of said hospital.”
Petitioner’s counsel seemed concerned primarily about obtaining a transfer for petitioner to a less restrictive wing of the hospital. See Tr. 11-12.
“A subsequent motion for unconditional release under § 301(k) was denied in March of 1977. Three months later, however, [petitioner] was granted conditional release on terms recommended by St. Elizabeths’ staff, allowing daytime and overnight visits into the community. He was also admitted into the civil division of the hospital, though as a result of disruptive behavior, he was retransferred to the forensic division.” 432 A. 2d, at 368. n. 6.
In the Court of Appeals petitioner apparently based these arguments on equal protection rather than due process, arguing that it was irrational for the Government to deny him a civil-commitment hearing at which the Government bore the burden of proof by clear and convincing evidence. See id., at 371. Both petitioner and the Government acknowledge that this equal protection argument essentially duplicates petitioner’s due process argument. That is, if the Due Process Clause does not require that an insanity acquittee be given the particular procedural safeguards provided in a civil-commitment hearing under Addington, then there necessarily is a rational basis for equal protection purposes for distinguishing between civil commitment and commitment of insanity acquittees. See Reply Brief for Petitioner 22-23; Brief for United States 55. We agree, and therefore address petitioner’s arguments in terms of the Due Process Clause.
Petitioner does raise one additional equal protection argument that stands on its own. The District of Columbia provides for a jury at civil-commitment hearings, see §21-544, and petitioner contends that equal protection requires that insanity acquittees also be permitted to demand a jury at the 50-day hearing. Because we determine that an acquittee’s commitment is based on the judgment of insanity at the criminal trial, rather than solely on the findings at the 50-day hearing, see infra, at 363-366, the relevant equal protection comparison concerns the procedures available at the criminal trial and at a civil-commitment hearing. We therefore agree with the Court of Appeals that the absence of a jury at the 50-day hearing “is justified by the fact that the acquittee has had a right to a jury determination of his sanity at the time of the offense.” 432 A. 2d, at 873.
It is important to note what issues are not raised in this case. Petitioner has not sought appellate review of the Superior Court’s findings in 1976 and 1977 that he remained mentally ill and dangerous, and, indeed, the record does not indicate that since 1977 he ever has sought a release hearing — a hearing to which he was entitled every six months.
Nor are we asked to decide whether the District’s procedures for release are constitutional. As noted above, see supra, at 357-359, the basic standard for release is the same under either civil commitment or commitment following acquittal by reason of insanity: the individual must prove by a preponderance of the evidence that he is no longer dangerous or mentally ill. There is an important difference, however, in the release provisions for these two groups. A patient who is committed civilly is entitled to unconditional release upon certification of his recovery by the hospital chief of service, see § 21-546, whereas a committed insanity acquittee may be released upon such certification only with court approval, see § 24-301(e). Neither of these provisions is before the Court, as petitioner has challenged neither the adequacy of the release standards generally nor the disparity in treatment of insanity acquittees and other committed persons. See 432 A. 2d. at 373. n. 19.
The proof beyond a reasonable doubt that the acquittee committed a criminal act distinguishes this case from Jackson v. Indiana, 406 U. S. 715 (1972), in which the Court held that a person found incompetent to stand trial could not be committed indefinitely solely on the basis of the finding of incompetency. In Jackson there never was any affirmative proof that the accused had committed criminal acts or otherwise was dangerous.
In attacking the predictive value of the insanity acquittal, petitioner complains that “[w]hen Congress enacted the present statutory scheme, it did not cite any empirical evidence indicating that mentally ill persons who have committed a criminal act are likely to commit additional dangerous acts in the future.” Reply Brief for Petitioner 13. He further argues that the available research fails to support the predictive value of prior dangerous acts. See id., at 13-14. We do not agree with the suggestion that Congress’ power to legislate in this area depends on the research conducted by the psychiatric community. We have recognized repeatedly the “uncertainty of diagnosis in this field and the tentativeness of professional judgment. The only certain thing that can be said about the present state of knowledge and therapy regarding mental disease is that science has not reached finality of judgment. . . .” Greenwood v. United States, 350 U. S. 366, 375 (1956). See Estelle v. Smith, 451 U. S. 454, 472 (1981); Addington v. Texas, 441 U. S. 418, 429-430 (1979); Powell v. Texas, 392 U. S. 514, 535-537 (1968) (plurality opinion). The lesson we have drawn is not that government may not act in the face of this uncertainty, but rather that courts should pay particular deference to reasonable legislative judgments.
See Overholser v. O’Beirne, 112 App. D. C. 267, 276, 302 F. 2d 852, 861 (1961) (Burger, J.) (“[T]o describe the theft of watches and jewelry as ‘non-dangerous’ is to confuse danger with violence. Larceny is usually less violent than murder or assault, but in terms of public policy the purpose of the statute is the same as to both”) (footnote omitted). Thus, the “danger” may be to property rights as well as to persons. It also may be noted that crimes of theft frequently may result in violence from the efforts of the criminal to escape or the victim to protect property or the police to apprehend the fleeing criminal.
The relative “dangerousness” of a particular individual, of course, should be a consideration at the release hearings. In this context, it is noteworthy that petitioner’s continuing commitment may well rest in significant part on evidence independent of his acquittal by reason of insanity of the crime of attempted larceny. In December 1976 a medical officer at St. Elizabeths reported that petitioner “has a history of attempted suicide.” Record 87. In addition, petitioner at one point was transferred to the civil division of the hospital, but was transferred back to the forensic division because of disruptive behavior. See n. 9, swpra. The Government also advises that after petitioner was released unconditionally following the second panel decision below, he had to be recommitted on an emergency civil basis two weeks later for conduct unrelated to the original commitment. See Brief for United States 15, n. 18.
See n. 2, swpra. In this case petitioner stipulated that he had committed the offense by reason of insanity.
That petitioner raised the insanity defense also diminishes' the significance of the deprivation. The Addington Court noted that the social stigma of civil commitment “can have a very significant impact on the individual.” 441 U. S., at 426. A criminal defendant who successfully raises the insanity defense necessarily is stigmatized by the verdict itself, and thus the commitment causes little additional harm in this respect.
A defendant could be required to prove his insanity by a higher standard than a preponderance of the evidence. See Leland v. Oregon, 343 U. S. 790, 799 (1952). Such an additional requirement hardly would benefit a criminal defendant who wants to raise the insanity defense, yet imposition of a higher standard would be a likely legislative response to a holding that an insanity acquittal could support automatic commitment only if the verdict were supported by clear and convincing evidence.
As the Court of Appeals held below, “[s]ociety may not excuse a defendant’s criminal behavior because of his insanity and at the same time punish him for invoking an insanity defense.” 432 A. 2d, at 369.
The Court has held that a convicted prisoner may be treated involuntarily for particular psychiatric problems, but that upon expiration of his prison sentence he may be committed only as would any other candidate for civil commitment. See McNeil v. Director, Patuxent Institution, 407 U. S. 245 (1972); Humphrey v. Cady, 405 U. S. 504 (1972); Baxstrom v. Herold, 383 U. S. 107 (1966). None of those cases involved an insanity acquittee, and none suggested that a person under noncriminal confinement could not be hospitalized in excess of the period for which he could have served in prison if convicted for the dangerous acts he had committed.
The inherent fallacy of relying on a criminal sanction to determine the length of a therapeutic confinement is manifested by petitioner’s failure to suggest any clear guidelines for deciding when a patient must be released. For example, he does not suggest whether the Due Process Clause would require States to limit commitment of insanity acquittees to maximum sen-tenees or minimum sentences. Nor does he explain what should be done in the case of indeterminate sentencing or suggest whether account would have to be taken of the availability of release time or the possibility of parole. And petitioner avoids entirely the important question how his theory would apply to those persons who committed especially serious criminal acts. Petitioner thus would leave the States to speculate how they may deal constitutionally with acquittees who might have received life imprisonment, life imprisonment without possibility of parole, or the death penalty.
A recent survey of commitment statutes reported that 14 jurisdictions provide automatic commitment for at least some insanity acquittees, while many other States have a variety of special methods of committing insanity acquittees. See Note, Commitment Following an Insanity Acquittal, 94 Harv. L. Rev. 605, 605-606, and nn. 4-6 (1981). Nineteen States commit insanity acquittees under the same procedures used for civil commitment. Id., at 605, n. 3. It appears that only one State has enacted into law petitioner’s suggested requirement that a committed insanity acquittee be released following expiration of his hypothetical maximum criminal sentence. See Conn. Gen. Stat. § 53a-47(b) (1981).