with whom Justice Stevens and Justice Souter join, and with whom Justice Ginsburg joins as to Parts II and III, dissenting.
I agree with the majority that the Kansas Sexually Violent Predator Act’s “definition of ‘mental abnormality’ ” satisfies the “substantive” requirements of the Due Process Clause. Ante, at 356. Kansas, however, concedes that Hendricks’ condition is treatable; yet the Act did not provide Hendricks (or others like him) with any treatment until after his release date from prison and only inadequate treatment thereafter. These, and certain other, special features of the Act convince me that it was not simply an effort to commit Hendricks civilly, but rather an effort to inflict further punishment upon him. The Ex Post Facto Clause therefore pro*374hibits the Act’s application to Hendricks, who committed his crimes prior to its enactment.
I — (
I begin with the area of agreement. This Court has held that the civil commitment of a “mentally ill” and “dangerous” person does not automatically violate the Due Process Clause provided that the commitment takes place pursuant to proper procedures and evidentiary standards. See Foucha v. Louisiana, 504 U. S. 71, 80 (1992); Addington v. Texas, 441 U. S. 418, 426-427 (1979). The Kansas Supreme Court, however, held that the Due Process Clause forbids application of the Act to Hendricks for “substantive” reasons, i. e., irrespective of the procedures or evidentiary standards used. The court reasoned that Kansas had not satisfied the “mentally ill” requirement of the Due Process Clause because Hendricks was not “mentally ill.” In re Hendricks, 259 Kan. 246, 260-261, 912 P. 2d 129, 137-138 (1996). Moreover, Kansas had not satisfied what the court believed was an additional “substantive due process” requirement, namely, the provision of treatment. Id., at 257-258, 912 P. 2d, at 136. I shall consider each of these matters briefly.
A
In my view, the Due Process Clause permits Kansas to classify Hendricks as a mentally ill and dangerous person for civil commitment purposes. Allen v. Illinois, 478 U. S. 364, 370-371, 373-375 (1986). I agree with the majority that the Constitution gives States a degree of leeway in making this kind of determination. Ante, at 359; Foucha, supra, at 87 (O’Connor, J., concurring in part and concurring in judgment); Jones v. United States, 463 U. S. 354, 365, n. 13 (1983). But, because I do not subscribe to all of its reasoning, I shall set forth three sets of circumstances that, taken together, convince me that Kansas has acted within the limits that the Due Process Clause substantively sets.
*375First, the psychiatric profession itself classifies the kind of problem from whieh Hendricks suffers as a serious mental disorder. E. g., American Psychiatric Assn., Diagnostic and Statistical Manual of Mental Disorders 524-525, 527-528 (4th ed. 1994) (describing range of paraphilias and discussing how stress aggravates pedophilic behavior); Abel & Rouleau, Male Sex Offenders, in Handbook of Outpatient Treatment of Adults 271 (M. Thase, B. Edelstein, & M. Hersen eds. 1990). I concede that professionals also debate whether or not this disorder should be called a mental “illness.” See R. Slovenko, Psychiatry and Criminal Culpability 57 (1995) (citing testimony that paraphilias are not mental illnesses); Schopp & Sturgis, Sexual Predators and Legal Mental Illness for Civil Commitment, 13 Behav. Sci. & The Law 437, 451-452 (1995) (same). Compare Brief for American Psychiatric Association as Amicus Curiae 26 (mental illness requirement not satisfied) with Brief for Menninger Clinic et al. as Amici Curiae 22-25 (requirement is satisfied). But the very presence and vigor of this debate is important. The Constitution permits a State to follow one reasonable professional view, while rejecting another. See Addington v. Texas, supra, at 431. The psychiatric debate, therefore, helps to inform the law by setting the bounds of what is reasonable, but it cannot here decide just how States must write their laws within those bounds. See Jones, supra, at 365, n. 13.
Second, Hendricks’ abnormality does not consist simply of a long course of antisocial behavior, but rather it includes a specific, serious, and highly unusual inability to control his actions. (For example, Hendricks testified that, when he gets “stressed out,” he cannot “control the urge” to molest children, see ante, at 355.) The law traditionally has considered. this kind of abnormality, akin to insanity for purposes of confinement. See, e. g., Minnesota ex rel. Pearson v. Probate Court of Ramsey Cty., 309 U. S. 270, 274 (1940) (upholding against a due process challenge the civil confinement of *376a dangerous person where the danger flowed from an “ 'utter lack of power to control... sexual impulses’ ”) (quoting State ex rel. Pearson v. Probate Court of Ramsey Cty., 205 Minn. 545, 555, 287 N. W. 297, 302 (1939)); 1788 N. Y. Laws, ch. 31 (permitting confinement of those who are “furiously mad”); In re Oakes, 8 Law Rep. 122, 125 (Mass. 1845) (Shaw, C. J.); A. Deutsch, The Mentally Ill in America 419-420 (1949) (tracing history of commitment of furiously mad people in 18th and 19th centuries); Dershowitz, The Origins of Preventative Confinement in Anglo-American Law — Part II: The American Experience, 43 U. Cin. L. Rev. 781 (1974). Indeed, the notion of an “irresistible impulse” often has helped to shape criminal law’s insanity defense and to inform the related recommendations of legal experts as they seek to translate the insights of mental health professionals into workable legal rules. See also American Law Institute, Model Penal Code § 4.01 (insanity defense, in part, rests on inability “to conform . . . conduct to the requirements of law”); A. Gold-stein, The Insanity Defense 67-79 (1967) (describing “irresistible impulse” test).
Third, Hendricks’ mental abnormality also makes him dangerous. Hendricks “has been convicted of ... a sexually violent offense,” and a jury found that he “suffers from a mental abnormality ... which makes” him “likely to engage” in similar “acts of sexual violence” in the future. Kan. Stat. Ann. §§ 59-29a02, 59-29a03 (1994). The evidence at trial favored the State. Dr. Befort, for example, explained why Hendricks was likely to commit further acts of sexual violence if released. See, e. g., App. 248-254. And Hendricks’ own testimony about what happens when he gets “stressed out” confirmed Dr. Befort’s diagnosis.
Because (1) many mental health professionals consider pedophilia a serious mental disorder; and (2) Hendricks suffers from a classic case of irresistible impulse, namely, he is so afflicted with pedophilia that he cannot “control the urge” to molest children; and (3) his pedophilia presents a serious *377danger to those children, I believe that Kansas can classify Hendricks as “mentally ill” and “dangerous” as this Court used those terms in Foucha.
The Kansas Supreme Court’s contrary conclusion rested primarily upon that court’s view that Hendricks would not qualify for civil commitment under Kansas’ own state civil commitment statute. The issue before us, however, is one of constitutional interpretation. The Constitution does not require Kansas to write all of its civil commitment rules in a single statute or forbid it to write two separate statutes each covering somewhat different classes of committable individuals. Moreover, Hendricks apparently falls outside the scope of the Kansas general civil commitment statute because that statute permits confinement, only of those who “lac[k] capacity to make an informed decision concerning treatment.” Kan.,Stat. Ann. §59-2902(h) (1994). The statute does not tell us why it imposes this requirement. Capacity to make an informed decision about treatment is not always or obviously incompatible with severe mental illness. Neither Hendricks nor his amici point to a uniform body of professional opinion that says as much, and we have not found any. See, e.g., American Psychiatric Assn., Guidelines for Legislation on the Psychiatric Hospitalization of Adults, 140 Am. J. Psychiatry 672, 673 (1983); Stromberg & Stone, A Model State Law on Civil Commitment of the Mentally Ill, 20 Harv. J. Legis. 275, 301-302 (1983); DeLand & Borenstein, Medicine Court, II, Rivers in Practice, 147 Am. J. Psychiatry 38 (1990). Consequently, the boundaries of the Federal Constitution and those of Kansas’ general civil commitment statute are not congruent.
B
The Kansas Supreme Court also held that the Due Process Clause requires a State to provide treatment to those whom it civilly confines (as “mentally ill” and “dangerous”). It found that Kansas did not provide Hendricks with significant *378treatment. And it concluded that Hendricks’ confinement violated the Due Process Clause for this reason as well.
This case does not require us to consider whether the Due Process Clause always requires treatment — whether, for example, it would forbid civil confinement of an untreatable mentally ill, dangerous person. To the contrary, Kansas argues that pedophilia is an “abnormality” or “illness” that can be treated. See Tr. of Oral Arg. 12 (Kansas Attorney General, in response to the question “you’re claiming that there is some treatability . . . ?” answering “[absolutely”); Brief for Petitioner 42-47. Two groups of mental health professionals agree. Brief for Association for the Treatment of Sexual Abusers as Amicus Curiae 11-12 (stating that “sex offenders can be treated” and that “increasing evidence” shows that “state-of-the-art treatment programs . . . significantly reduce recidivism”); Brief for Menninger Foundation et al. as Amici Curiae 28. Indeed, no one argues the contrary. Hence the legal question before us is whether the Clause forbids Hendricks’ confinement unless Kansas provides him with treatment that it concedes is available.
Nor does anyone argue that Kansas somehow could have violated the Due Process Clause’s treatment concerns had it provided Hendricks with the treatment that is potentially available (and I do not see how any such argument could succeed). Rather, the basic substantive due process treatment question is whether that Clause requires Kansas to provide treatment that it concedes is potentially available to a person whom it concedes is treatable. This same question is at the heart of my discussion of whether Hendricks’ confinement violates the Constitution’s Ex Post Facto Clause. See infra, at 383-395. For that reason, I shall not consider the substantive due process treatment question separately, but instead shall simply turn to the Ex Post Facto Clause discussion. As Justice Kennedy points out, ante, p. 371, some of the matters there discussed may later prove relevant to substantive due process analysis.
*379h — i HH
Kansas’ 1994 Act violates the Federal Constitution’s prohibition of “any ... ex post facto Law” if it “inflicts” upon Hendricks “a greater punishment” than did the law “annexed to” his “erime[s]” when he “committed” those crimes in 1984. Colder v. Bull, 3 Dall. 386, 390 (1798) (opinion of Chase, J.); U. S. Const., Art. I, § 10. The majority agrees that the Clause “ ‘forbids the application of any new punitive measure to a crime already consummated.’” California Dept. of Corrections v. Morales, 514 U. S. 499, 505 (1995) (citation omitted; emphasis added). Ante, at 370-371. But it finds the Act is not “punitive.” With respect to that basic question, I disagree with the majority.
Certain resemblances between the Act’s “civil commitment” and traditional criminal punishments are obvious. Like criminal imprisonment, the Act’s civil commitment amounts to “secure” confinement, Kan. Stat. Ann. § 59— 29a07(a) (1994), and “incarceration against one’s will,” In re Gault, 387 U. S. 1, 50 (1967). See Testimony of Terry Davis, SRS Director of Quality Assurance, App. 52-54, 78-81 (confinement takes place in the psychiatric wing of a prison hospital where those whom the Act confines and ordinary prisoners are treated alike). Cf. Browning-Ferris Industries of Vt., Inc. v. Kelco Disposal, Inc., 492 U. S. 257, 298 (1989) (O’Connor, J., concurring in part and dissenting in part). In addition, a basic objective of the Act is incapacitation, which, as Blaekstone said in describing an objective of criminal law, is to “depriv[e] the party injuring of the power to do future mischief.” 4 W. Blaekstone, Commentaries *11-* 12 (incapacitation is one important purpose of criminal punishment); see also Foucha, 504 U. S., at 99 (Kennedy, J., dissenting) (“Incapacitation for the protection of society is not an unusual ground for incarceration”); United States v. Brown, 381 U. S. 437, 458 (1965) (“Punishment serves several purposes: retributive, rehabilitative, deterrent — and preventative. One of the reasons society imprisons those convicted *380of crimes is to keep them from inflicting future harm, but that does not make imprisonment any the less punishment”); 1 W. LaFave & A. Scott, Substantive Criminal Law § 1.5, p. 32 (1986); 18 U. S. C. § 3553(a); United States Sentencing Guidelines, Guidelines Manual, ch. 1, pt. A (Nov. 1995).
Moreover, the Act, like criminal punishment, imposes its confinement (or sanction) only upon an individual who has previously committed a criminal offense. Kan. Stat. Ann. §§ 59-29a02(a), 59-29a03(a) (1994). Cf. Department of Revenue of Mont. v. Kurth Ranch, 511 U. S. 767, 781 (1994) (fact that a tax on marijuana was “conditioned on the commission of a crime” is “ ‘significant of [its] penal and prohibitory intent’ ” (citation omitted)); Lipke v. Lederer, 259 U. S. 557, 561-562 (1922). And the Act imposes that confinement through the use of persons (county prosecutors), procedural guarantees (trial by jury, assistance of counsel, psychiatric evaluations), and standards (“beyond a reasonable doubt”) traditionally associated with the criminal law. Kan. Stat. Ann. §§ 59-29a06, 59-29a07 (1994).
These obvious resemblances by themselves, however, are not legally sufficient to transform what the Act calls “civil commitment” into a criminal punishment. Civil commitment of dangerous, mentally ill individuals by its very nature involves confinement and incapacitation. Yet “civil commitment,” from a constitutional perspective, nonetheless remains civil. Allen v. Illinois, 478 U. S., at 369-370. Nor does the fact that criminal behavior triggers the Act make the critical difference. The Act’s insistence upon a prior crime, by screening out those whose past behavior does not concretely demonstrate the existence of a mental problem or potential future danger, may serve an important noncriminal evidentiary purpose. Neither is the presence of criminal law-type procedures determinative. Those procedures can serve an important purpose that in this context one might consider noncriminal, namely, helping to prevent judgmental *381mistakes that would wrongly deprive a person of important liberty. Id., at 371-372.
If these obvious similarities cannot by themselves prove that Kansas’ “civil commitment” statute is criminal, neither can the word “civil” written into the statute, §59-29a01, by itself prove the contrary. This Court has said that only the “clearest proof” could establish that a law the legislature called “civil” was, in reality, a “punitive” measure. United States v. Ward, 448 U. S. 242, 248-249 (1980). But the Court has also reiterated that a “civil label is not always disposi-tive,” Allen v. Illinois, supra, at 369; it has said that in close cases the label is “ ‘not of paramount importance,’ ” Kurth Ranch, supra, at 777 (citation omitted); and it has looked behind a “civil” label fairly often, e. g., United States v. Halper, 490 U. S. 435, 447 (1989).
In this circumstance, with important features of the Act pointing in opposite directions, I would place particular importance upon those features that would likely distinguish between a basically punitive and a basically nonpunitive purpose. United States v. Ursery, 518 U. S. 267, 278 (1996) (asking whether a statutory scheme was so punitive “ ‘either in purpose or effect’ ” to negate the legislature’s “ ‘intention to establish a civil remedial mechanism’ ” (citations omitted)). And I note that the Court, in an earlier civil commitment case, Allen v. Illinois, 478 U. S., at 369, looked primarily to the law’s concern for treatment as an important distinguishing feature. I do not believe that Allen means that a particular law’s lack of concern for treatment, by itself, is enough to make an incapacitative law punitive. But, for reasons I will point out, when a State believes that treatment does exist, and then couples that admission with a legislatively required delay of such treatment until a person is at the end of his jail term (so that further incapacitation is therefore necessary), such a legislative scheme begins to look punitive.
In Allen, the Court considered whether, for Fifth Amendment purposes, proceedings under an Illinois statute were *382civil or “criminal.” The Illinois statute, rather like the Kansas statute here, authorized the confinement of persons who were sexually dangerous, who had committed at least one prior sexual assault, and who suffered from a “mental disorder.” Id., at 366, n. 1. The Allen Court, looking behind the statute’s “civil commitment” label, found the statute civil— in important part because the State had “provided for the treatment of those it commits.” Id., at 370 (also referring to facts that the State had “disavowed any interest in punishment” and that it had “established a system under which committed persons may be released after the briefest time in confinement”).
In reaching this conclusion, the Court noted that the State Supreme Court had found the proceedings “‘essentially civil’ ” because the statute’s aim was to provide “ ‘treatment, not punishment.’ ” Id., at 367 (quoting People v. Allen, 107 Ill. 2d 91, 99-101, 481 N. E. 2d 690, 694-695 (1985)). It observed that the State had “a statutory obligation to provide ‘care and treatment . . . designed to effect recovery’ ” in a “facility set aside to provide psychiatric care.” 478 U. S., at 369 (quoting Ill. Rev. Stat., ch. 38, ¶ 105-8 (1985)). And it referred to the State’s purpose as one of “treating rather than punishing sexually dangerous persons.” 478 U. S., at 373; see also ibid. (“Had petitioner shown, for example, that the confinement . . . imposes ... a regimen which is essentially identical to that imposed upon felons with no need for psychiatric care, this might well be a different case”).
The Allen Court’s focus upon treatment, as a kind of touchstone helping to distinguish civil from punitive purposes, is not surprising, for one would expect a nonpunitive statutory scheme to confine, not simply in order to protect, but also in order to cure. That is to say, one would expect a nonpunitively motivated legislature that confines because of a dangerous mental abnormality to seek to help the individual himself overcome that abnormality (at least insofar as professional treatment for the abnormality exists and is *383potentially helpful, as Kansas, supported by some groups of mental health professionals, argues is the case here, see supra, at 378). Conversely, a statutory scheme that provides confinement that does not reasonably fit a practically available, medically oriented treatment objective, more likely reflects a primarily punitive legislative purpose.
Several important treatment-related factors — factors of a kind that led the five-Member Allen majority to conclude that the Illinois Legislature’s purpose was primarily civil, not punitive — in this action suggest precisely the opposite. First, the State Supreme Court here, unlike the state court in Allen, has held that treatment is not a significant objective of the Act. The Kansas court wrote that the Act’s purpose is “segregation of sexually violent offenders,” with “treatment” a matter that was “incidental at best.” 259 Kan., at 258, 912 P. 2d, at 136. By way of contrast, in Allen the Illinois court had written that “‘treatment, not punishment,’” was “the aim of the statute.” Allen, supra, at 367 (quoting People v. Allen, supra, at 99-101, 481 N. E. 2d, at 694-695).
We have generally given considerable weight to the findings of state and lower federal courts regarding the intent or purpose underlying state officials’ actions, see U. S. Term Limits, Inc. v. Thornton, 514 U. S. 779, 829 (1995) (ordinarily “[w]e must . . . accept the state court’s view of the purpose of its own law”); Romer v. Evans, 517 U. S. 620, 626 (1996); Hernandez v. New York, 500 U. S. 352, 366-370 (1991) (plurality opinion); id., at 372 (O’Connor, J., concurring); Edwards v. Aguillard, 482 U. S. 578, 594, n. 15 (1987); b.ut see Department of Revenue of Mont. v. Kurth Ranch, 511 U. S., at 776, 780, n. 18; Stone v. Graham, 449 U. S. 39,40-43 (1980) (per curiam); Consolidated Edison Co. of N. Y. v. Public Serv. Comm’n of N. Y, 447 U. S. 530, 533, 535-537 (1980), although the level of deference given to such findings varies with the circumstances, Crawford v. Board of Ed. of Los Angeles, 458 U. S. 527, 544, n. 30 (1982), and is not always as conclusive as a state court’s construction of one of its stat*384utes, see, e. g., R. A. V. v. St. Paul, 505 U. S. 377, 381 (1992). For example, Allen’s dissenters, as well as its majority, considered the state court’s characterization of the state law’s purpose an important factor in determining the constitutionality of that statute. Allen, 478 U. S., at 380 (Stevens, J., dissenting) (describing the state court as “the final authority on the . .. purpose” of the statute).
The record provides support for the Kansas court’s conclusion. The court found that, as of the time of Hendricks’ commitment, the State had not funded treatment, it had not entered into treatment contracts, and it had little, if any, qualified treatment staff. See 259 Kan., at 249, 258, 912 P. 2d, at 131, 136; Testimony of Dr. Charles Befort, App. 255 (acknowledging that he has no specialized training); Testimony of John House, SRS Attorney, id., at 367 (no contract has been signed by bidders); Testimony of John House, SRS Attorney, id., at 369 (no one hired to operate sexually violent predator (SVP) program or to serve as clinical director, psychiatrist, or psychologist). Indeed, were we to follow the majority’s invitation to look beyond the record in this case, an invitation with which we disagree, see infra, at 391-393, it would reveal that Hendricks, according to the commitment program’s own director, was receiving “essentially no treatment.” Dr. Charles Befort in State Habeas Corpus Proceeding, App. 393; 259 Kan., at 249, 258, 912 P. 2d, at 131, 136. See also App. 421 (“[T]he treatment that is prescribed by statute” is “still not available”); id., at 420-421 (the “needed treatment” “hasn’t been delivered yet” and “Hendricks has wasted ten months” in “terms of treatment effects”); id., at 391-392 (Dr. Befort admitting that he is not qualified to be SVP program director).
It is therefore not surprising that some of the Act’s official supporters had seen in it an opportunity permanently to confine dangerous sex offenders, e. g., id., at 468 (statement of Attorney General Robert Stephan); id., at 475-476, 478 (statement of Special Assistant to the Attorney General *385Carla Stovall). Others thought that effective treatment did not exist, id., at 503 (statement of Jim Blaufuss) (“Because there is no effective treatment for sex offenders, this Bill may mean a life sentence for a felon that is considered a risk to women and children. SO BE IT!”) — a view, by the way, that the State of Kansas, supported by groups of informed mental health professionals, here strongly denies. See supra, at 378.
The Kansas court acknowledged the existence of “provisions of the Act for treatment” (although it called them “somewhat disingenuous”). 259 Kan., at 258, 912 P. 2d, at 136. Cf. Kan. Stat. Ann. § 59-29a01 (1994) (legislative findings that “prognosis for rehabilitation]... in a prison setting is poor,... treatment needs ... long term” and “commitment procedure for . . . long term care and treatment . . . necessary”); § 59-29a09 (“commitment... shall conform to constitutional requirements for care and treatment”). Nor did the court deny that Kansas could later increase the amount of treatment it provided. But the Kansas Supreme Court could, and did, use the Act’s language, history, and initial implementation to help it characterize the Act’s primary purposes.
Second, the Kansas statute, insofar as it applies to previously convicted offenders such as Hendricks, commits, confines, and treats those offenders after they have served virtually their entire criminal sentence. That time-related circumstance seems deliberate. The Act explicitly defers diagnosis, evaluation, and commitment proceedings until a few weeks prior to the “anticipated release” of a previously convicted offender from prison. Kan. Stat. Ann. §59-29a03(a)(1) (1994). But why, one might ask, does the Act not commit and require treatment of sex offenders sooner, say, soon after they begin to serve their sentences?
An Act that simply seeks confinement, of course, would not need to begin civil commitment proceedings sooner. Such an Act would have to begin proceedings only when an *386offender’s prison term ends, threatening his release from the confinement that imprisonment assures. But it is difficult to see why rational legislators who seek treatment would write the Act in this way — providing treatment years after the criminal act that indicated its necessity. See, e. g., Wettstein, A Psychiatric Perspective on Washington’s Sexually Violent Predators Statute, 15 U. Puget Sound L. Rev. 597, 617 (1992) (stating that treatment delay leads to “loss of memory” and makes it “more difficult for the offender” to “accept responsibility,” and that time in prison leads to attitude hardening that “engender[s] a distorted view of the precipitating offense”). And it is particularly difficult to see why legislators who specifically wrote into the statute a finding that “prognosis for rehabilitating ... in a prison setting is poor” would leave an offender in that setting for months or years before beginning treatment. This is to say, the timing provisions of the statute confirm the Kansas Supreme Court’s view that treatment was not a particularly important legislative objective.
I recognize one possible counterargument. A State, wanting both to punish Hendricks (say, for deterrence purposes) and also to treat him, might argue that it should be permitted to postpone treatment until after punishment in order to make certain that the punishment in fact occurs. But any such reasoning is out of place here. Much of the treatment that Kansas offered here (called “ward milieu” and “group therapy”) can be given at the same time as, and in the same place where, Hendricks serves his punishment. See, e. g., Testimony of Leroy Hendricks, App. 142-143, 150, 154, 179-181 (stating that Washington and Kansas had both provided group therapy to Hendricks, and that he had both taken and refused such treatment at various points); Testimony of Terry Davis, SRS Director of Quality Assurance, id., at 78-81 (pointing out that treatment under the Act takes place in surroundings very similar to those in which prisoners receive treatment); Testimony of John House, SRS *387Attorney, id., at 375-376. See also Task Force on Community Protection, Final Report to Booth Gardner, Governor State of Washington II—2 (1989) (findings of task force that developed the Washington State Act, which served as a model for Kansas’ Act, stating that “[s]ex offenders can be treated during incarceration”). The evidence adduced at the state habeas proceeding, were we to assume it properly before the Court, see infra, at 392-393, supports this conclusion as well. See Testimony of Dr. Befort at State Habeas Proceeding, App. 399, 406-408 (describing treatment as ward milieu and group therapy); id., at 416-417 (stating that Kansas offers similar treatment, on a voluntary basis, to prisoners). Hence, assuming, arguendo, that it would be otherwise permissible, Kansas need not postpone treatment in order to make certain that sex offenders serve their full terms of imprisonment, i. e., to make certain that they receive the entire punishment that Kansas criminal law provides. To the contrary, the statement in the Act itself, that the Act aims to respond to special “long term” “treatment needs,” suggests that treatment should begin during imprisonment. It also suggests that, were those long-term treatment needs (rather than further punishment) Kansas’ primary aim, the State would require that treatment begin soon after conviction, not 10 or more years later. See also Vt. Stat. Ann., Tit. 18, § 2815 (1959) (providing for treatment of sexual psychopaths first, and punishment afterwards).
Third, the statute, at least as of the time Kansas applied it to Hendricks, did not require the committing authority to consider the possibility of using less restrictive alternatives, such as postrelease supervision, halfway houses, or other methods that amici supporting Kansas here have mentioned. Brief for Menninger Foundation et al. as Amici Curiae 28; Brief for Association for the Treatment of Sexual Abusers as Amicus Curiae 11-12. The laws of many other States require such consideration. See Appendix, infra.
*388This Court has said that a failure to consider, or to use, “alternative and less harsh methods” to achieve a nonpuni-tive objective can help to show that legislature’s “purpose ... was to punish.” Bell v. Wolfish, 441 U. S. 520, 539, n. 20 (1979). And one can draw a similar conclusion here. Legislation that seeks to help the individual offender as well as to protect the public would avoid significantly greater restriction of an individual’s liberty than public safety requires. See Keilitz, Conn, & Gianpetro, Least Restrictive Treatment of Involuntary Patients: Translating Concepts into Practice, 29 St. Louis U. L. J. 691, 693 (1985) (describing “least restrictive alternativ[e]” provisions in the ordinary civil commitment laws of almost all States); Lyon, Levine, & Zusman, Patients’ Bill of Rights: A Survey of State Statutes, 6 Mental Disability L. Rep. 178, 181-183 (1982) (same). Legislation that seeks almost exclusively to incapacitate the individual through confinement, however, would not necessarily concern itself with potentially less restrictive forms of incapacitation. I would reemphasize that this is not a case in which the State claims there is no treatment potentially available. Rather, Kansas, and supporting amici, argue that pedophilia is treatable. See supra, at 378.
Fourth, the laws of other States confirm, through comparison, that Kansas’ “civil commitment” objectives do not require the statutory features that indicate a punitive purpose. I have found 17 States with laws that seek to protect the public from mentally abnormal, sexually dangerous individuals through civil commitment or other mandatory treatment programs. Ten of those statutes, unlike the Kansas statute, begin treatment of an offender soon after he has been apprehended and charged with a serious sex offense. Only seven, like Kansas, delay “civil” commitment (and treatment) until the offender has served his criminal sentence (and this figure includes the Acts of Minnesota and New Jersey, both of which generally do not delay treatment). Of these seven, however, six (unlike Kansas) require consideration of less re*389strictive alternatives. See Ariz. Rev. Stat. Ann. §§ 13-4601, 4606B (Supp. 1996-1997); Cal. Welf. & Inst. Code Ann. §§ 6607, 6608 (West Supp. 1997); Minn. Stat. §253B.09 (1996); N. J. Stat. Ann. §30:4-27.11d (West 1997); Wash. Rev. Code Ann. §71.09.090 (Supp. 1996-1997); Wis. Stat. § 980.06(2)(b) (Supp. 1993-1994). Only one State other than Kansas, namely Iowa, both delays civil commitment (and consequent treatment) and does not explicitly consider less restrictive alternatives. But the law of that State applies prospectively only, thereby avoiding ex post facto problems. See Iowa Code Ann. §709C.12 (Supp. 1997) (Iowa SVP Act only “applies to persons convicted of a sexually violent offense on or after July 1, 1997”); see also Appendix, infra. Thus the practical experience of other States, as revealed by their statutes, confirms what the Kansas Supreme Court’s finding, the timing of the civil commitment proceeding, and the failure to consider less restrictive alternatives, themselves suggest, namely, that for Ex Post Facto Clause purposes, the purpose of the Kansas Act (as applied to previously convicted offenders) has a punitive, rather than a purely civil, purpose.
Kansas points to several cases as support for a contrary conclusion. It points to Allen — which is, as we have seen, a ease in which the Court concluded that Illinois’ “civil commitment” proceedings were not criminal. I have explained in detail, however, how the statute here differs from that in Allen, and why Allen’s reasoning leads to a different conclusion in this litigation. See supra, at 381-388 and this page.
Kansas also points to Addington v. Texas, where the Court held that the Constitution does not require application of criminal law’s “beyond a reasonable doubt” standard in a civil commitment proceeding. 441 U. S., at 428. If some criminal law guarantees such as “reasonable doubt” did not apply in Addington, should other guarantees, such as the prohibition against ex post facto laws, apply here? The answer to this question, of course, lies in the particular statute at issue in Addington — a Texas statute that, this Court ob*390served, did “not exercis[e]” state power “in a punitive sense." Ibid. That statute did not add civil commitment’s confinement to imprisonment; rather civil commitment was, at most, a substitute for criminal punishment. See Tex. Rev. Civ. Stat. Ann. § 5547-41 (Vernon 1958) (petition must state “proposed patient is not charged with a crime or [is] charged [but] transferred ... for civil commitment proceedings”). And this Court, relying on the Texas Supreme Court’s interpretation, wrote that the “State of Texas confines only for the purpose of providing care designed to treat the individual." Addington, supra, at 428, n. 4 (citing State v. Turner, 556 S. W. 2d 563, 566 (1977)). Cf. Specht v. Patterson, 386 U. S. 605, 608-609 (1967) (separate postconviction sexual psychopath commitment/sentencing proceeding held after conviction for serious sex crime, imposes a “criminal punishment even though . . . designed not so much as retribution as ... to keep individuals from inflicting future harm”). Nothing I say here would change the reach or holding of Addington in any way. That, is, a State is free to commit those who are dangerous and mentally ill in order to treat them. Nor does my decision preclude a State from deciding that a certain subset of people are mentally ill, dangerous, and untreatable, and that confinement of this subset is therefore necessary (again, assuming that all the procedural safeguards of Addington are in place). But when a State decides offenders can be treated and confines an offender to provide that treatment, but then refuses to provide it, the refusal to treat while a person is fully incapacitated begins to look punitive.
The majority suggests that this is the very case I say it is not, namely, a case of a mentally ill person who is untreatable. Ante, at 365. And it quotes a long excerpt from the Kansas Supreme Court’s opinion in support. That court, however, did not find that Hendricks was untreatable; it found that he was untreated — quite a different matter. Had the Kansas Supreme Court thought that Hendricks, or oth*391ers like him, are untreatable, it could not have written the words that follow that excerpt, adopting by reference the words of another court opinion:
‘“The statute forecloses the possibility that offenders will be evaluated and treated until after they have been punished. . . . Setting aside the question of whether a prison term exacerbates or minimizes the mental condition of a sex offender, it plainly delays the treatment that must constitutionally accompany commitment pursuant to the Statute. The failure of the Statute to provide for examination or treatment prior to the completion of the punishment phase strongly suggests that treatment is of secondary, rather than primary, concern.’ ” 259 Kan., at 258, 912 P. 2d, at 136 (quoting Young v. Weston, 898 F. Supp. 744, 753 (WD Wash. 1995)).
This quotation, and the rest of the opinion, make clear that the court is finding it objectionable that the statute, among other things, has not provided adequate treatment to one who, all parties here concede, can be treated.
The majority suggests in the alternative that recent evidence shows that Kansas is now providing treatment. Ante, at 366-368. That evidence comes from two sources: First, a statement by the Kansas Attorney General at oral argument that those committed under the Act are now receiving treatment, ante, at 368; and second, in a footnote, a Kansas trial judge’s statement, in a state habeas proceeding nearly one year after Hendricks was committed, that Kansas is providing treatment. Ante, at 368, n. 5. I do not see how either of these statements can be used to justify the validity of the Act’s application to Hendricks at the time he filed suit.
We are reviewing the Kansas Supreme Court’s determination. Of Hendricks’ case. Neither the majority nor the lengthy dissent in that court referred to the two facts that the majority now seizes upon, and for good reason. That court denied a motion to take judicial notice of the state *392habeas proceeding, see Order of Kansas Supreme Court, No. 94-73039, Mar. 1,1996. The proceeding is thus not part of the record, and cannot properly be considered by this Court. And the Kansas Supreme Court obviously had no chance to consider Kansas’ new claim made at. oral argument before this Court. There is simply no evidence in the record before this Court that comes even close to resembling the assertion Kansas made at oral argument. It is the record, not the parties’ view of it, that must control our decision. See Russell v. Southard, 12 How. 139, 158-159 (1851); Adickes v. S. H. Kress & Co., 398 U. S. 144, 157-158, n. 16 (1970); Hopt v. Utah, 114 U. S. 488, 491-492 (1885); Witters v. Washington Dept. of Servs. for Blind, 474 U. S. 481, 489, n. 3 (1986); New Haven Inclusion Cases, 399 U. S. 392, 450, n. 66 (1970); R. Stern, E. Gressman, S. Shapiro, & K. Geller, Supreme Court Practice 555-556, 594 (7th ed. 1993); Fed. Rule Evid. 201(b).
The prohibition on facts found outside the record is designed to ensure the reliability of the evidence before the Court. For purposes of my argument in this dissent, however, the material that the majority wishes to consider, when read in its entirety, shows that Kansas was not providing treatment to Hendricks. At best, the testimony at the state hearing contained general and vague references that treatment was about to be provided, but it contains no statement that Hendricks himself was receiving treatment. And it provides the majority with no support at all in respect to that key fact. Indeed, it demonstrates the contrary conclusion. For example, the program’s director, Dr. Befort, testified that he would have to tell the court at Hendricks’ next annual review, in October 1995, that Hendricks “has had no opportunity for meaningful treatment.” App. 400. He also stated that SVP’s were receiving “essentially no treatment” and that the program does not “have adequate staffing.” Id., at 393,394. And Dr. Befort’s last words made clear that Hendricks has “wasted ten months ... in terms of treatment *393effects” and that, as far as treatment goes, “[t]oday, it’s still not available.” Id., at 420-421. Nor does the assertion made by the Kansas Attorney General at oral argument help the majority. She never stated that Hendricks, as opposed to other SVP’s, was receiving this treatment. And we can find no support for her statement in the record.
We have found no other evidence in the record to support the conclusion that Kansas was in fact providing the treatment that all parties agree that it could provide. Thus, even had the Kansas Supreme Court considered the majority’s new evidence — which it did not — it is not likely to have changed its characterization of the Act’s treatment provisions as “somewhat disingenuous.” 259 Kan., at 258, 912 P. 2d, at 186.
Regardless, the Kansas Supreme Court did so characterize the Act’s treatment provisions and did find that treatment was “at best” an “incidental” objective. Thus, the circumstances here are different from Allen, where the Illinois Supreme Court explicitly found that the statute’s aim was to provide treatment, not punishment. See supra, at 382-384. There is no evidence in the record that contradicts the finding of the Kansas court. Thus, Allen’s approach — its reliance on the state court — if followed here would mean the Act as applied to Leroy Hendricks (as opposed to others who may have received treatment or who were sentenced after the effective date of the Act) is punitive.
Finally, Kansas points to United States v. Salerno, 481 U. S. 739 (1987), a case in which this Court held preventive detention of a dangerous accused person pending trial constitutionally permissible. Salerno, however, involved the brief detention of that person, after a finding of “probable cause” that he had committed a crime that would justify further imprisonment, and only pending a speedy judicial determination of guilt or innocence. This Court, in Foucha, emphasized the fact that the confinement at issue in Salerno was “strictly limited in duration.” 504 U. S., at 82. It described *394that “pretrial detention of arrestees” as “one of those carefully limited exceptions permitted by the Due Process Clause.” Id., at 83. And it held that Salerno did not authorize the indefinite detention, on grounds of dangerousness, of “insanity acquittees who are not mentally ill but who do not prove they would not be dangerous to others.” 504 U. S., at 83. Whatever Salerno's “due process” implications may be, it does not focus upon, nor control, the question at issue here, the question of “punishment” for purposes of the Ex Post Facto Clause.
One other case warrants mention. In Kennedy v. Mendoza-Martinez, 372 U. S. 144 (1963), this Court listed seven factors that helped it determine whether a particular statute was primarily punitive for purposes of applying the Fifth and Sixth Amendments. Those factors include whether a sanction involves an affirmative restraint, how history has regarded it, whether it applies to behavior already a crime, the need for a finding of scienter, its relationship to a traditional aim of punishment, the presence of a nonpunitive alternative purpose, and whether it is excessive in relation to that purpose. Id., at 169. This Court has said that these seven factors are “neither exhaustive nor disposi-tive,” but nonetheless “helpful.” Ward, 448 U. S., at 249. Paraphrasing them here, I believe the Act before us involves an affirmative restraint historically regarded as punishment; imposed upon behavior already a crime after a finding of scienter; which restraint, namely, confinement, serves a traditional aim of punishment, does not primarily serve an alternative purpose (such as treatment), and is excessive in relation to any alternative purpose assigned. 372 U. S., at 168-169.
This is not to say that each of the factors the Court mentioned in Martinez-Mendoza on balance argues here in favor of a constitutional characterization as “punishment.” It is not to say that I have found “a single ‘formula’ for identifying those legislative changes that have a sufficient effect on *395substantive crimes or punishments to fall within the constitutional prohibition,” Morales, 514 U. S., at 509; see also Halper, 490 U. S., at 447; id., at 453 (Kennedy, J., concurring). We have not previously done so, and I do not do so here. Rather, I have pointed to those features of the Act itself, in the context of this litigation, that lead me to conclude, in light of our precedent, that the added confinement the Act imposes upon Hendricks is basically punitive. This analysis, rooted in the facts surrounding Kansas’ failure to treat Hendricks, cannot answer the question whether the Kansas Act, as it now stands, and in light of its current implementation, is punitive toward people other than he. And I do not attempt to do so here.
Ill
To find that the confinement the Act imposes upon Hendricks is “punishment” is to find a violation of the Ex Post Facto Clause. Kansas does not deny that the 1994 Act changed the legal consequences that attached to Hendricks’ earlier crimes, and in a way that significantly “disadvantage^] the offender,” Weaver v. Graham, 450 U. S. 24, 29 (1981). See Brief for Respondent State of Kansas 37-39.
To find a violation of that Clause here, however, is not to hold that the Clause prevents Kansas, or other States, from enacting dangerous sexual offender statutes. A statute that operates prospectively, for example, does not offend the Ex Post Facto Clause. Weaver, 450 U. S., at 29. Neither does it offend the Ex Post Facto Clause for a State to sentence offenders to the fully authorized sentence, to seek consecutive, rather than concurrent, sentences, or to invoke recidivism statutes to lengthen imprisonment. Moreover, a statute that operates retroactively, like Kansas’ statute, nonetheless does not offend the Clause if the confinement that it imposes is not punishment — if, that is to say, the legislature does not simply add a later criminal punishment to an earlier one. Ibid.
*396The statutory provisions before us do amount to punishment primarily because, as I have said, the legislature did not tailor the statute to fit the nonpunitive civil aim of treatment, which it concedes exists in Hendricks’ case. The Clause in these circumstances does not stand as an obstacle to achieving important protections for the public’s safety; rather it provides an assurance that, where so significant a restriction of an individual’s basic freedoms is at issue, a State cannot cut corners. Rather, the legislature must hew to the Constitution’s liberty-protecting line. See The Federalist No. 78, p. 466 (C. Rossiter ed. 1961) (A. Hamilton).
I therefore would affirm the judgment below.
*397APPENDIX TO OPINION OF BREYER, J.
Selected Sexual Offense Commitment Statutes
(Kansas is the only State that answers “yes” to all three categories)
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*398Selected Sexual Offense Commitment Statutes — Continued
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