CERTIORARI TO THE DISTRICT OF COLUMBIA COURT OF APPEALS.
Powell, J., delivered the opinion of the Court, in which Burger, C. J., and White, Rehnquist, and O'connor, JJ., joined. Brennan, J., filed a dissenting opinion, in which Marshall and Blackmun, JJ., joined, post, p. 371. Stevens, J., filed a dissenting opinion, post, p. 387.
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 § 24-301(j) (1981).*fn1 If he successfully invokes the insanity defense, he is committed to a mental hospital. § 24-301(d)(1).*fn2 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).*fn3 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).*fn4
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).*fn5
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).*fn6 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).
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.*fn7 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)(1).
On May 25, 1976, the court held the 50-day hearing required by § 24-301(d)(2)(A). A psychologist from St. Elizabeths 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.*fn8 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.*fn9
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.
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 ("[The] 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.*fn10 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 acquittee 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.*fn11
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 ...