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guish right from wrong and was insane at the time of the offense.1 On October 12, 1984, the trial court ruled that Foucha was not guilty by reason of insanity, finding that he "is unable to appreciate the usual, natural and probable consequences of his acts; that he is unable to distinguish right from wrong; that he is a menace to himself and others; and that he was insane at the time of the commission of the above crimes and that he is presently insane." Id., at 6. He was committed to the East Feliciana Forensic Facility until such time as doctors recommend that he be released, and until further order of the court. In 1988, the superintendent of Feliciana recommended that Foucha be discharged or released. A three-member panel was convened at the institution to determine Foucha's current condition and whether he could be released or placed on probation without being a danger to others or himself. On March 21, 1988, the panel reported that there had been no evidence of mental illness since admission and recommended that Foucha be conditionally discharged.2 The trial judge appointed a two-member sanity commission made up of the same two doctors who had conducted the pretrial examination. Their written report stated that Foucha "is presently in remission from mental illness [but] [w]e cannot certify that he would not constitute

1 Louisiana law provides: "If the circumstances indicate that because of a mental disease or mental defect the offender was incapable of distinguishing between right and wrong with reference to the conduct in question, the offender shall be exempt from criminal responsibility." La. Rev. Stat. Ann. §14:14 (West 1986). JUSTICE KENNEDY disregards the fact that the State makes no claim that Foucha was criminally responsible or that it is entitled to punish Foucha as a criminal.

2 The panel unanimously recommended that petitioner be conditionally discharged with recommendations that he (1) be placed on probation; (2) remain free from intoxicating and mind-altering substances; (3) attend a substance abuse clinic on a regular basis; (4) submit to regular and random urine drug screening; and (5) be actively employed or seeking employment. App. 10-11.

Although the panel recited that it was charged with determining dangerousness, its report did not expressly make a finding in that regard.

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a menace to himself or others if released." Id., at 12. One of the doctors testified at a hearing that upon commitment Foucha probably suffered from a drug induced psychosis but that he had recovered from that temporary condition; that he evidenced no signs of psychosis or neurosis and was in "good shape" mentally; that he had, however, an antisocial personality, a condition that is not a mental disease and that is untreatable. The doctor also testified that Foucha had been involved in several altercations at Feliciana and that he, the doctor, would not "feel comfortable in certifying that [Foucha] would not be a danger to himself or to other people." Id., at 18.

After it was stipulated that the other doctor, if he were present, would give essentially the same testimony, the court ruled that Foucha was dangerous to himself and others and ordered him returned to the mental institution. The Court of Appeal refused supervisory writs, and the State Supreme Court affirmed, holding that Foucha had not carried the burden placed upon him by statute to prove that he was not dangerous, that our decision in Jones v. United States, 463 U.S. 354 (1983), did not require Foucha's release, and that neither the Due Process Clause nor the Equal Protection Clause was violated by the statutory provision permitting confinement of an insanity acquittee based on dangerousness alone.

Because the case presents an important issue and was decided by the court below in a manner arguably at odds with prior decisions of this Court, we granted certiorari. 499 U. S. 946 (1991).

II

Addington v. Texas, 441 U. S. 418 (1979), held that to commit an individual to a mental institution in a civil proceeding, the State is required by the Due Process Clause to prove by clear and convincing evidence the two statutory preconditions to commitment: that the person sought to be committed is mentally ill and that he requires hospitalization for his

Opinion of the Court

own welfare and protection of others. Proof beyond a reasonable doubt was not required, but proof by preponderance of the evidence fell short of satisfying due process.3

When a person charged with having committed a crime is found not guilty by reason of insanity, however, a State may commit that person without satisfying the Addington burden with respect to mental illness and dangerousness. Jones v. United States, supra. Such a verdict, we observed in Jones, "establishes two facts: (i) the defendant committed an act that constitutes a criminal offense, and (ii) he committed the act because of mental illness," id., at 363, an illness that the defendant adequately proved in this context by a preponderance of the evidence. From these two facts, it could be properly inferred that at the time of the verdict, the defendant was still mentally ill and dangerous and hence could be committed.4

3 JUSTICE THOMAS in dissent complains that Foucha should not be released based on psychiatric opinion that he is not mentally ill because such opinion is not sufficiently precise-because psychiatry is not an exact science and psychiatrists widely disagree on what constitutes a mental illness. That may be true, but such opinion is reliable enough to permit the courts to base civil commitments on clear and convincing medical evidence that a person is mentally ill and dangerous and to base release decisions on qualified testimony that the person is no longer mentally ill or dangerous. It is also reliable enough for the State not to punish a person who by a preponderance of the evidence is found to have been insane at the time he committed a criminal act, to say nothing of not trying a person who is at the time found incompetent to understand the proceedings. And more to the point, medical predictions of dangerousness seem to be reliable enough for JUSTICE THOMAS to permit the State to continue to hold Foucha in a mental institution, even where the psychiatrist would say no more than that he would hesitate to certify that Foucha would not be dangerous to himself or others.

4 JUSTICE KENNEDY's assertion that we overrule the holding of Jones described in the above paragraph is fanciful at best. As that paragraph plainly shows, we do not question and fully accept that insanity acquittees may be initially held without complying with the procedures applicable to civil committees. As is evident from the ensuing paragraph of the text, we are also true to the further holding of Jones that both JUSTICE THOMAS

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We held, however, that "[t]he committed acquittee is entitled to release when he has recovered his sanity or is no longer dangerous," id., at 368; i. e., the acquittee may be held as long as he is both mentally ill and dangerous, but no longer. We relied on O'Connor v. Donaldson, 422 U. S. 563 (1975), which held as a matter of due process that it was unconstitutional for a State to continue to confine a harmless, mentally ill person. Even if the initial commitment was permissible, "it could not constitutionally continue after that basis no longer existed." Id., at 575. In the summary of our holdings in our opinion we stated that "the Constitution permits the Government, on the basis of the insanity judg

and JUSTICE KENNEDY reject: that the period of time during which an insanity acquittee may be held in a mental institution is not measured by the length of a sentence that might have been imposed had he been convicted; rather, the acquittee may be held until he is either not mentally ill or not dangerous. Both Justices would permit the indefinite detention of the acquittee, although the State concedes that he is not mentally ill and although the doctors at the mental institution recommend his release, for no reason other than that a psychiatrist hesitates to certify that the acquittee would not be dangerous to himself or others.

JUSTICE KENNEDY asserts that we should not entertain the proposition that a verdict of not guilty by reason of insanity differs from a conviction. Post, at 94. Jones, however, involved a case where the accused had been "found, beyond a reasonable doubt, to have committed a criminal act.” 463 U. S., at 364. We did not find this sufficient to negate any difference between a conviction and an insanity acquittal. Rather, we observed that a person convicted of crime may of course be punished. But "[d]ifferent considerations underlie commitment of an insanity acquittee. As he was not convicted, he may not be punished." Id., at 369.

JUSTICE KENNEDY observes that proof beyond reasonable doubt of the commission of a criminal act permits a State to incarcerate and hold the offender on any reasonable basis. There is no doubt that the States have wide discretion in determining punishment for convicted offenders, but the Eighth Amendment ensures that discretion is not unlimited. The Justice cites no authority, but surely would have if it existed, for the proposition that a defendant convicted of a crime and sentenced to a term of years may nevertheless be held indefinitely because of the likelihood that he will commit other crimes.

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ment, 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." Jones, 463 U. S., at 368, 370.5 The court below was in error in characterizing the above language from Jones as merely an interpretation of the pertinent statutory law in the District of Columbia and as having no constitutional significance. In this case, Louisiana does not contend that Foucha was mentally ill at the time of the trial court's hearing. Thus, the basis for holding Foucha in a psychiatric facility as an insanity acquittee has disappeared, and the State is no longer entitled to hold him on that basis. O'Connor, supra, at 574–575.

The State, however, seeks to perpetuate Foucha's confinement at Feliciana on the basis of his antisocial personality which, as evidenced by his conduct at the facility, the court found rendered him a danger to himself or others. There are at least three difficulties with this position. First, even if his continued confinement were constitutionally permissible, keeping Foucha against his will in a mental institution is improper absent a determination in civil commitment proceedings of current mental illness and dangerousness. In Vitek v. Jones, 445 U. S. 480 (1980), we held that a convicted felon serving his sentence has a liberty interest, not extinguished by his confinement as a criminal, in not being transferred to a mental institution and hence classified as men

5 JUSTICE THOMAS, dissenting, suggests that there was no issue of the standards for release before us in Jones. The issue in that case, however, was whether an insanity acquittee "must be released because he has been hospitalized for a period longer than he might have served in prison had he been convicted," 463 U. S., at 356; and in the course of deciding that issue in the negative, we said that the detainee could be held until he was no longer mentally ill or no longer dangerous, regardless of how long a prison sentence might have been. We noted in footnote 11 that Jones had not sought a release based on nonillness or nondangerousness, but as indicated in the text, we twice announced the outside limits on the detention of insanity acquittees. The Justice would "wish" away this aspect of Jones, but that case merely reflected the essence of our prior decisions.