Justice Kennedy
delivered the opinion of the Court.
In the Commonwealth of Kentucky, involuntary civil commitments of those alleged to be mentally retarded and of those alleged to be mentally ill are governed by separate statutory procedures. Two differences between these commitment proceedings are at issue in this case. First, at a final commitment hearing, the applicable burden of proof for involuntary commitment based on mental retardation is clear and convincing evidence, Ky. Rev. Stat. Ann. §202B. 160(2) (Michie 1991), while the standard for involuntary commitment based on mental illness is beyond a reasonable doubt, § 202A.076(2). Second, in commitment proceedings for mental retardation, unlike for mental illness, "[g]uardians and immediate family members" of the subject of the proceedings "may participate . as if a party to the proceedings," with all attendant rights, including the right to present evidence and to appeal. § 202B. 160(3). Respondents are a class of mentally retarded persons committed involuntarily to Kentucky institutions. They argue that these distinctions are irrational and violate the Equal Protection Clause of the Fourteenth Amendment. They claim also that granting close family members and guardians the status of parties violates the Due Process Clause. We reject these contentions and hold the Kentucky statutes constitutional.
I
This case has a long and complicated history. It began in 1982 when respondents filed suit against petitioner, the Kentucky Secretary of the Cabinet for Human Resources, claiming that Kentucky's failure to provide certain procedural protections before institutionalizing people on the basis of mental retardation violated the Constitution. Kentucky has amended its civil commitment statutes several times since 1982, with each new statute being attacked in court by respondents. As the previous incarnations of this lawsuit have little effect on the issues currently before this Court, we limit our discussion to the current round of the litigation. See Doe v. Cowherd, 770 F. Supp. 354, 355-356 (WD Ky. 1991) (recounting the procedural history).
At issue here are elements of Kentucky's statutory procedures, enacted in 1990, for the involuntary commitment of the mentally retarded. In many respects the procedures governing commitment of the mentally retarded and the mentally ill are parallel. The statutes recognize a large class of persons who can petition for an individual's involuntary commitment, whether on grounds of mental retardation or mental illness. Ky. Rev. Stat. Ann. §202B.100(3) (Michie 1991) (mental retardation); §202A.051 (mental illness). Upon filing of the petition, the trial court must appoint counsel to represent the individual in question, unless he retains private counsel. § 202B.210 (mental retardation); § 202A.121 (mental illness). The trial court also must examine the person who filed the petition and, if there is probable cause to believe that the individual who is the subject of the petition should be involuntarily committed, the court must order his examination by two qualified professionals. §202B.100(5), (6)(c) (mental retardation); § 202A.051(5), (6)(c) (mental illness). The subject of the proceeding has the right to retain a professional of his own choosing, who may "witness and participate in any examination" of him. §202B.140 (mental retardation); §202A.066 (mental illness). In cases of commitment for mental retardation, a professional retained by the subject's "parent or guardian" also must be permitted to witness and participate in any examination. §202B.140.
If both qualified professionals certify that the individual meets the criteria for involuntary commitment, the trial court must conduct a preliminary hearing. § 202B.130 (mental retardation); §202A.061 (mental illness). At the hearing, the court must receive as evidence the reports of these two professionals and any other professional retained under the statute. §202B.160(1) (mental retardation); §202A.076(1) (mental illness). The individual whose commitment is sought may testify and may call and cross-examine witnesses. §202B.160(1) (mental retardation); §202A.076(1) (mental illness). In cases of mental retardation, at both the preliminary hearing and, if there is one, the final hearing, Kentucky law provides particular rights to guardians and immediate family members:
"Guardians and immediate family members of the respondent shall be allowed to attend all hearings, conferences or similar proceedings; may be represented by private counsel, if desired; may participate in the hearings or conferences as if a party to the proceedings; may cross-examine witnesses if desired; and shall have standing to appeal any adverse decision." § 202B. 160(3)
See also § 202B.230. If the trial court determines that there is probable cause to believe that the subject should be involuntarily committed, it proceeds to a final hearing. §202B.100(8) (mental retardation); §202A.051(9) (mental illness).
At the final hearing, the State, through the county attorney for the county in which the person subject to the proceeding lives, prosecutes the petition, § 202B.019 (mental retardation); § 202A.016 (mental illness); Tr. of Oral Arg. 33-35, and counsel for the person defends against institutionalization, id., at 31,34, 54. At this hearing, "[t]he manner of proceeding and the rules of evidence shall be the same as those in any criminal proceeding." §202B. 160(2) (mental retardation); §202A.076(2) (mental illness). As in the preliminary hearing, the subject of the proceedings may testify and call and cross-examine witnesses. §202B. 160(2) (mental retardation); §202A.076(2) (mental illness). In proceedings for commitment based on mental retardation, the standard of proof is clear and convincing evidence, § 202B. 160(2); for mental illness, the standard is proof beyond a reasonable doubt, § 202A.076(2). For commitment of the mentally retarded, four propositions must be proved by clear and convincing evidence: "(1) The person is a mentally retarded person; (2) The person presents a danger or a threat of danger to self, family, or others; (3) The least restrictive alternative mode of treatment presently available requires placement in [a residential treatment center]; and (4) Treatment that can reasonably benefit the person is available in [a residential treatment center]." §202B.040. The criteria for commitment of the mentally ill are in substance identical, requiring proof beyond a reasonable doubt that an individual "is a mentally ill person: (1) Who presents a danger or threat of danger to self, family or others as a result of the mental illness; (2) Who can reasonably benefit from treatment; and (3) For whom hospitalization is the least restrictive alternative mode of treatment presently available." §202A.026. Appeals from involuntary commitment proceedings are taken in the same manner as other appeals from the trial court. §202B.230 (mental retardation); §202A.141 (mental illness).
After enactment of the 1990 modifications, respondents moved for summary judgment in their pending lawsuit against petitioner. They argued, among other things, that the differences in treatment between the mentally retarded and the mentally ill — the different standards of proof and the right of immediate family members and guardians to participate as parties in commitment proceedings for the mentally retarded but not the mentally ill — violated the Equal Protection Clause's prohibition of distinctions that lack a rational basis, and that participation by family members and guardians violated the Due Process Clause. The District Court for the Western District of Kentucky accepted these arguments and granted summary judgment to respondents on these and other grounds not at issue here, 770 F. Supp. 354 (1991), and the Court of Appeals for the Sixth Circuit affirmed, Doe v. Cowherd, 965 F. 2d 109 (1992). We granted Kentucky's petition for certiorari, 506 U. S. 939 (1992), and now reverse.
II
Respondents contend that, in evaluating the constitutionality of the distinctions drawn by Kentucky's statutes, we should apply not rational-basis review, but some form of heightened scrutiny. Brief for Respondents 23-32. This claim is not properly presented. Respondents argued before the District Court and the Court of Appeals only that Kentucky's statutory scheme was subject to rational-basis review, and the courts below ruled on that ground. Indeed, respondents have conceded that they pressed their heightened scrutiny argument for the first time in their merits brief in this Court. Id., at 23 ("[Respondents did not argue this particular issue below..."). Even if respondents were correct that heightened scrutiny applies, it would be inappropriate for us to apply that standard here. Both parties have been litigating this case for years on the theory of rational-basis review, which, as noted below, see infra, at 320, does not require the State to place any evidence in the record, let alone the extensive evidentiary showing that would be required for these statutes to survive heightened scrutiny. It would be imprudent and unfair to inject a new standard at this stage in the litigation. See Tennessee v. Dunlap, 426 U. S. 312, 316, n. 3 (1976); Ernst & Ernst v. Hochfelder, 425 U. S. 185, 215 (1976). We therefore decide this case as it has been' presented to the courts whose judgments are being reviewed.
Ill
We many times have said, and but weeks ago repeated, that rational-basis review in equal protection analysis "is not a license for courts to judge the wisdom, fairness, or logic of legislative choices." FCC v. Beach Communications, Inc., 508 U. S. 307, 313 (1993). See also, e. g., Dandridge v. Williams, 397 U. S. 471, 486 (1970). Nor does it authorize "the judiciary [to] sit as a superlegislature to judge the wisdom or desirability of legislative policy determinations made in areas that neither affect fundamental rights nor proceed along suspect lines." New Orleans v. Dukes, 427 U. S. 297, 303 (1976) (per curiam). For these reasons, a classification neither involving fundamental rights nor proceeding along suspect lines is accorded a strong presumption of validity. See, e. g., Beach Communications, supra, at 314-315; Kadrmas v. Dickinson Public Schools, 487 U. S. 450, 462 (1988); Hodel v. Indiana, 452 U. S. 314, 331-332 (1981); Massachusetts Bd. of Retirement v. Murgia, 427 U. S. 307, 314 (1976) (per curiam). Such a classification cannot run afoul of the Equal Protection Clause if there is a rational relationship between the disparity of treatment and some legitimate governmental purpose. See, e. g., Nordlinger v. Hahn, 505 U. S. 1, 11 (1992); Dukes, supra, at 303. Further, a legislature that creates these categories need not "actually articulate at any time the purpose or rationale supporting its classification." Nordlinger, supra, at 15. See also, e. g., United States Railroad Retirement Bd. v. Fritz, 449 U. S. 166, 179 (1980); Allied Stores of Ohio, Inc. v. Bowers, 358 U. S. 522, 528 (1959). Instead, a classification "must be upheld against equal protection challenge if there is any reasonably conceivable state of facts that could provide a rational basis for the classification." Beach Communications, supra, at 313. See also, e. g., Nordlinger, supra, at 11; Sullivan v. Stroop, 496 U. S. 478, 485 (1990); Fritz, supra, at 174-179; Vance v. Bradley, 440 U. S. 93, 111 (1979); Dandridge v. Williams, supra, at 484-485.
A State, moreover, has no obligation to produce evidence to sustain the rationality of a statutory classification. "[A] legislative choice is not subject to courtroom factfinding and may be based on rational speculation unsupported by evidence or empirical data." Beach Communications, supra, at 315. See also, e.g., Vance v. Bradley, supra, at 111; Hughes v. Alexandria Scrap Corp., 426 U. S. 794, 812 (1976); Locomotive Firemen v. Chicago, R. I. & P. R. Co., 393 U. S. 129, 139 (1968). A statute is presumed constitutional, see supra, at 319, and "[t]he burden is on the one attacking the legislative arrangement to negative every conceivable basis which might support it," Lehnhausen v. Lake Shore Auto Parts Co., 410 U. S. 356, 364 (1973) (internal quotation marks omitted), whether or not the basis has a foundation in the record. Finally, courts are compelled under rational-basis review to accept a legislature's generalizations even when there is an imperfect fit between means and ends. A classification does not fail rational-basis review because it " 'is not made with mathematical nicety or because in practice it results in some inequality.'" Dandridge v. Williams, supra, at 485, quoting Lindsley v. Natural Carbonic Gas Co., 220 U. S. 61, 78 (1911). "The problems of government are practical ones and may justify, if they do not require, rough accommodations — illogical, it may be, and unscientific." Metropolis Theatre Co. v. Chicago, 228 U. S. 61, 69-70 (1913). See also, e. g., Burlington Northern R. Co. v. Ford, 504 U. S. 648, 651 (1992); Vance v. Bradley, supra, at 108, and n. 26; New Orleans v. Dukes, supra, at 303; Schweiker v. Wilson, 450 U. S. 221, 234 (1981). We have applied rational-basis review in previous cases involving the mentally retarded and the mentally ill. See Cleburne v. Cleburne Living Center, Inc., 473 U. S. 432 (1985); Schweiker v. Wilson, supra. In neither case did we purport to apply a different standard of rational-basis review from that just described.
True, even the standard of rationality as we so often have defined it must find some footing in the realities of the subject addressed by the legislation. That requirement is satisfied here. Kentucky has proffered more than adequate justifications for the differences in treatment between the mentally retarded and the mentally ill.
A
Kentucky argues that a lower standard of proof in commitments for mental retardation follows from the fact that mental retardation is easier to diagnose than is mental illness. That general proposition should cause little surprise, for mental retardation is a developmental disability that becomes apparent before adulthood. See American Psychiatric Assn., Diagnostic and Statistical Manual of Mental Dis orders 29 (3d rev. ed. 1987) (hereinafter Manual of Mental Disorders); American Assn, on Mental Retardation, Mental Retardation: Definition, Classification, and Systems of Support 5,16-18 (9th ed. 1992) (hereinafter Mental Retardation); S. Brakel, J. Parry, & B. Weiner, The Mentally Disabled and the Law 16-17, 37 (3d ed. 1985) (hereinafter Mentally Disabled); Ky. Rev. Stat. Ann. §202B.010(9) (Michie 1991). By the time the person reaches 18 years of age the documentation and other evidence of the condition have been accumulated for years. Mental illness, on the other hand, may be sudden and may not occur, or at least manifest itself, until adulthood. See, e. g., Manual of Mental Disorders 190 (onset of schizophrenia may occur any time during adulthood); id., at 220, 229 (onset of depression usually is during adulthood). Furthermore, as we recognized in an earlier case, diagnosis of mental illness is difficult. See Addington v. Texas, 441 U. S. 418, 430 (1979). See also Mentally Disabled 18. Kentucky's basic premise that mental retardation is easier to diagnose than is mental illness has a sufficient basis in fact. See, e. g., id., at 16; Ellis & Luckasson, Mentally Retarded Criminal Defendants, 53 Geo. Wash. L. Rev. 414, 438-439 (1985).
This difference between the two conditions justifies Kentucky's decision to assign a lower standard of proof in commitment proceedings involving the mentally retarded. In assigning the burden of proof, Kentucky was determining the "risk of error" faced by the subject of the proceedings. Addington v. Texas, supra, at 423. If diagnosis is more difficult in cases of mental illness than in instances of mental retardation, a higher burden of proof for the former tends to equalize the risks of an erroneous determination that the subject of a commitment proceeding has the condition in question. See G. Keppel, Design and Analysis 65-68 (1973). From the diagnostic standpoint alone, Kentucky's differential burdens of proof (as well as the other statutory distinction at issue, see infra, at 328-329) are rational.
There is, moreover, a "reasonably conceivable state of facts," Beach Communications, 508 U. S., at 313, from which Kentucky could conclude that the second prerequisite to commitment — that "[t]he person presents a danger or a threat of danger to self, family, or others," Ky. Rev. Stat. Ann. §202B.040 (Michie 1991) — is established more easily, as a general rule, in the case of the mentally retarded. Previous instances of violent behavior are an important indicator of future violent tendencies. See, e. g., J. Monahan, The Clinical Prediction of Violent Behavior 71-72 (1981) (hereinafter Monahan); Kozol, Boucher, & Garofalo, The Diagnosis and Treatment of Dangerousness, 18 Crime & Delinquency 371, 384 (1972). Mental retardation is a permanent, relatively static condition, see Mentally Disabled 37, so a determination of dangerousness may be made with some accuracy based on previous behavior. We deal here with adults only, so almost by definition in the case of the retarded there is an 18-year record upon which to rely.
This is not so with the mentally ill. Manifestations of mental illness may be sudden, and past behavior may not be an adequate predictor of future actions. Prediction of future behavior is complicated as well by the difficulties in herent in diagnosis of mental illness. Developments in the Law — Civil Commitment of the Mentally Ill, 87 Harv. L. Rev. 1190, 1242-1243 (1974). It is thus no surprise that many psychiatric predictions of future violent behavior by the mentally ill are inaccurate. See, e.g., Steadman, Employing Psychiatric Predictions of Dangerous Behavior: Policy vs. Fact, in Dangerous Behavior: A Problem in Law and Mental Health 123,125-128 (C. Frederick ed. 1978); Monahan 47-49. For these reasons, it would have been plausible for Kentucky to conclude that the dangerousness determination was more accurate as to the mentally retarded than the mentally ill.
A statutory classification fails rational-basis review only when it " 'rests on grounds wholly irrelevant to the achievement of the State's objective.'" Holt Civic Club v. Tuscaloosa, 439 U. S. 60, 71 (1978), quoting McGowan v. Maryland, 366 U. S. 420, 425 (1961). See also, e. g., McDonald v. Board of Election Comm'rs of Chicago, 394 U. S. 802, 809 (1969); Kotch v. Board of River Port Pilot Comm'rs for Port of New Orleans, 330 U. S. 552, 556 (1947). Because ease of diagnosis is relevant to two of the four inquiries, it is not "wholly irrelevant" to the achievement of Kentucky's objective, and thus the statutory difference in the applicable burden of proof survives rational-basis review. In any event, it is plausible for Kentucky to have found that, for purposes of determining the acceptable risk of error, diagnosis and dangerousness are the most critical factors in the commitment decision, so the appropriate burden of proof should be tied to them.
There is a further, more far-reaching rationale justifying the different burdens of proof: The prevailing methods of treatment for the mentally retarded, as a general rule, are much less invasive than are those given the mentally ill. The mentally ill are subjected to medical and psychiatric treatment which may involve intrusive inquiries into the patient's innermost thoughts, see Meissner & Nicholi, The Psy chotherapies: Individual, Family, and Group, in The Harvard Guide to Modern Psychiatry 357-385 (A. Nicholi ed. 1978) (hereinafter Harvard Guide), and use of psychotropic drugs, see Baldessarini, Chemotherapy, in Harvard Guide 387-431; Berger, Medical Treatment of Mental Illness, 200 Science 974 (1978); Mentally Disabled 327-330; Brief for American Psychological Association as Amicus Curiae in Washington v. Harper, O. T. 1988, No. 88-599, pp. 10-11. By contrast, the mentally retarded in general are not subjected to these medical treatments. Rather, " 'because mental retardation is... a learning disability and training impairment rather than an illness,' " Youngberg v. Romeo, 457 U. S. 307, 309, n. 1 (1982), quoting Brief for American Psychiatric Association as Amicus Curiae in Youngberg v. Romeo, O. T. 1981, No. 80-1429, p. 4, n. 1, the mentally retarded are provided "habilitation," which consists of education and training aimed at improving self-care and self-sufficiency skills. See Youngberg, supra, at 309, n. 1; M. Rosen, G. Clark, & M. Kivitz, Habilitation of the Handicapped 47-59 (1977); Mentally Disabled 332.
It is true that the loss of liberty following commitment for mental illness and mental retardation may be similar in many respects; but the different treatment to which a committed individual is subjected provides a rational basis for Kentucky to decide that a greater burden of proof is needed before a person may be committed for mental illness. The procedures required before the government acts often depend on the nature and extent of the burden or deprivation to be imposed. See Addington v. Texas, 441 U. S., at 423-424. For example, because confinement in prison is punitive and hence more onerous than confinement in a mental hospital, id., at 428, the Due Process Clause subjects the former to proof beyond a reasonable doubt, In re Winship, 397 U. S. 358 (1970), whereas it requires in the latter case only clear and convincing evidence, Addington v. Texas, supra. It may also be true that some persons committed for mental retardation are subjected to more intrusive treatments while confined. See post, at 342-346 (Souter, J., dissenting). Nonetheless, it would have been plausible for the Kentucky Legislature to believe that most mentally retarded individuals who are committed receive treatment that is different from, and less invasive than, that to which the mentally ill are subjected. "States are not required to convince the courts of the correctness of their legislative judgments." Minnesota v. Clover Leaf Creamery Co., 449 U. S. 456, 464 (1981). Thus, since "'the question is at least debatable,'" Western & Southern Life Ins. Co. v. State Bd. of Equalization of Cal., 451 U. S. 648, 674 (1981), quoting United States v. Carolene Products Co., 304 U. S. 144, 154 (1938), rational-basis review permits a legislature to use just this sort of generalization.
These distinctions may explain, too, the differences in treatment between the mentally retarded and the mentally ill that have long existed in Anglo-American law. At English common law there was a "marked distinction" in the treatment accorded "idiots" (the mentally retarded) and "lunatics" (the mentally ill). 1 F. Pollock & F. Maitland, The History of English Law 481 (2d ed. 1909) (hereinafter Pollack and Maitland). As Blackstone explained, a retarded person became a ward of the King, who had a duty to preserve the individual's estate and provide him with "necessaries," but the King could profit from the wardship. In contrast, the King was required to "provide for the custody and sustentation of [the mentally ill], and preserve their lands and the profits of them," but the King was prohibited from profiting thereby. 1 W. Blackstone, Commentaries *302-*304. See Pollack and Maitland 481; S. Herr, Rights and Advocacy for Retarded People 9-10 (1983).
Ancient lineage of a legal concept does not give it immunity from attack for lacking a rational basis. That the law has long treated the classes as distinct, however, suggests that there is a commonsense distinction between the men tally retarded and the mentally ill. The differentiation continues to the present day. A large majority of States have separate involuntary commitment laws for the two groups, and many States as well have separate agencies for addressing their needs.
Kentucky's burden of proof scheme, then, can be explained by differences in the ease of diagnosis and the accuracy of the prediction of future dangerousness and by the nature of the treatment received after commitment. Each of these rationales, standing on its own, would suffice to establish a rational basis for the distinction in question.
B
There is a rational basis also for the other distinction challenged by respondents: that Kentucky allows close relatives and guardians to participate as parties in proceedings to commit the mentally retarded but not the mentally ill. As we have noted, see supra, at 321-322, by definition, mental retardation has its onset during a person's developmental period. Mental retardation, furthermore, results in "deficits or impairments in adaptive functioning," that is to say, "the person's effectiveness in areas such as social skills, communication, and daily living skills, and how well the person meets the standards of personal independence and social responsibility expected of his or her age by his or her cultural group." Manual of Mental Disorders 28-29. See also Mental Retardation 5-6, 15-16, 38-41. Based on these facts, Kentucky may have concluded that close relatives and guardians, both of whom likely have intimate knowledge of a mentally retarded person's abilities and experiences, have valuable insights that should be considered during the involuntary commitment process.
Mental illness, by contrast, may arise or manifest itself with suddenness only after minority, see supra, at 322, when the afflicted person's immediate family members have no knowledge of the medical condition and have long ceased to provide care and support. Further, determining the proper course of treatment may be far less dependent upon observations made in a household setting. Indeed, we have noted the severe difficulties inherent in psychiatric diagnosis conducted by experts in the field. Addington v. Texas, 441 U. S., at 430. See also Mentally Disabled 18. In addition, adults previously of sound mental health who are diagnosed as mentally ill may have a need for privacy that justifies the State in confining a commitment proceeding to the smallest group compatible with due process. Based on these facts, Kentucky may have concluded that participation as parties by relatives and guardians of the mentally ill would not in most cases have been of sufficient help to the trier of fact to justify the additional burden and complications of granting party status. To be sure, Kentucky could have provided rel atives and guardians of the mentally retarded some participation in commitment proceedings by methods short of providing them status as parties. That, however, is irrelevant in rational-basis review. We do not require Kentucky to have chosen the least restrictive means of achieving its legislative end. San Antonio Independent School Dist. v. Rodriguez, 411 U. S. 1, 51 (1973). As long as Kentucky "rationally advances a reasonable and identifiable governmental objective, we must disregard" the existence of alternative methods of furthering the objective "that we, as individuals, perhaps would have preferred." Schweiker v. Wilson, 450 U. S., at 235.
IV
We turn now to respondents' claim that one aspect of the involuntary commitment procedures violates procedural due process. We note at the outset that respondents challenge as violative of due process only those provisions of Kentucky's comprehensive involuntary commitment procedures that allow participation in the proceedings by guardians and immediate family members. See Ky. Rev. Stat. Ann. §202B.140, 202B.160(3), 202B.230 (Michie 1991). Respondents claim that by allowing the participation of persons whose interests may be adverse to those of the individual facing possible involuntary commitment, the statute "skews the balance" against the retarded individual and therefore imposes a burden on him. Brief for Respondents 32-36. Both courts below apparently accepted this argument, almost without explanation. See 965 F. 2d, at 113; 770 F. Supp., at 358. In our view, the claim is without merit.
We evaluate the sufficiency of this procedural rule under Mathews v. Eldridge, 424 U. S. 319 (1976). There we held that determining the dictates of due process requires consideration of three factors:
"First, the private interest that will be affected by the official action; second, the risk of an erroneous depriva tion of such interest through the procedures used, and the probable value, if any, of additional or substitute procedural safeguards; and finally, the Government's interest, including the function involved and the fiscal and administrative burdens that the additional or substitute procedural requirement would entail." Id., at 335.
We think that application of the Mathews v. Eldridge factors compels the conclusion that participation as parties by close relatives and legal guardians is not a deprivation of due process. Even if parents, close family members, or legal guardians can be said in certain instances to have interests "adverse to [those of] the person facing commitment," 965 F. 2d, at 113, we simply do not understand how their participation as formal parties in the commitment proceedings increases "the risk of an erroneous deprivation," 424 U. S., at 335, of respondents' liberty interest. Rather, for the reasons explained, supra, at 329, these parties often will have valuable information that, if placed before the court, will increase the accuracy of the commitment decision. Kentucky law, moreover, does not allow intervention by persons who lack a personal stake in the outcome of the adjudication. Guardians have a legal obligation to further the interests of their wards, and parents and other close relatives of a mentally retarded person, after living with and caring for the individual for 18 years or more, have an interest in his welfare that the State may acknowledge. See Parham v. J. R., 442 U. S. 584, 602-603 (1979). For example, parents who for 18 years or longer have cared for a retarded child can face changed circumstances resulting from their own advancing age, when the physical, emotional, and financial costs of caring for the adult child may become too burdensome for the child's best interests to be served by care in their home. There is no support whatever in our cases or our legal tradition for the "statist notion," id., at 603, that the State's expertise and concern in these matters is so superior to that of parents and other close family members that the State must slam the courthouse door against those interested enough to intervene. Finally, "the state has a legitimate interest under its parens patriae powers in providing care to its citizens who are unable . to care for themselves," as well as "authority under its police power to protect the community" from any dangerous mentally retarded persons. Addington, 441 U. S., at 426.
To be sure, if the additional parties involved in the proceedings favor commitment, their participation may increase the chances that the result of the proceeding will be a decision to commit. That fact, however, is beside the point. "The Due Process Clause does not . . . require a State to adopt one procedure over another on the basis that it may produce results more favorable to" the party challenging the existing procedures. Medina v. California, 505 U. S. 437, 451 (1992).
"The function of legal process, as that concept is embodied in the Constitution, and in the realm of factfinding, is to minimize the risk of erroneous decisions. Because of the broad spectrum of concerns to which the term must apply, flexibility is necessary to gear the process to the particular need; the quantum and quality of the process due in a particular situation depend upon the need to serve the purpose of minimizing the risk of error." Greenholtz v. Inmates of Neb. Penal and Correctional Complex, 442 U. S. 1, 13 (1979).
See also Fuentes v. Shevin, 407 U. S. 67, 97 (1972) (due process functions to "prevent unfair and mistaken deprivations"). At least to the extent protected by the Due Process Clause, the interest of a person subject to governmental action is in the accurate determination of the matters before the court, not in a result more favorable to him. So long as the accuracy of the adjudication is unaffected, therefore, the Due Process Clause does not prevent a State from allowing the intervention of immediate family members and legal guard ians, even if in some instances these parties will have interests adverse to those of the subject of the proceedings. Neither respondents nor their amici have suggested that accuracy would suffer from the intervention allowed by Kentucky law, and as noted above we think quite the opposite is true.
Because allowing guardians and immediate family members to participate as parties in commitment proceedings increases the accuracy of those proceedings and implements the State's interest in providing family members a voice in the proceedings, without undermining those interests of the individual protected by the Due Process Clause, these Kentucky statutes do not run afoul of due process. "We deal here with issues of unusual delicacy, in an area where professional judgments regarding desirable procedures are constantly and rapidly changing. In such a context, restraint is appropriate on the part of courts called upon to adjudicate whether a particular procedural scheme is adequate under the Constitution." Smith v. Organization of Foster Families for Equality & Reform, 431 U. S. 816, 855-856 (1977).
V
In sum, there are plausible rationales for each of the statutory distinctions challenged by respondents in this case. It could be that "[t]he assumptions underlying these rationales [are] erroneous, but the very fact that they are 'arguable' is sufficient, on rational-basis review, to 'immunize' the [legislative] choice from constitutional challenge." Beach Communications, 508 U. S., at 320, quoting Vance v. Bradley, 440 U. S., at 112.
The judgment of the Court of Appeals for the Sixth Circuit is
Reversed.
Justice Souter suggests that this description of the function of burdens of proof is inconsistent with Addington v. Texas, 441 U. S. 418 (1979). See post, at 339-341 (dissenting opinion). His reasoning, however, would impose the due process conception of burdens of proof on a State's policy decision as to which standard is most appropriate in the circumstances. The Due Process Clause sets the minimum standard of proof required in particular contexts, based on consideration both of the respective interests of the State and individual and of the risk of erroneous decisions. Adding-ton, supra, at 425. A State is free to adopt any burden of proof that meets or exceeds the constitutional minimum required by due process, and a State may select a standard of proof based on any rational policy of its choice. It may seek, as Justice Souter would require, to balance the respective interests of the affected parties. See post, at 339. But it may also calibrate its standard of proof in an effort to establish the risk of error at a certain level.
Ala. Code §22-52-50 et seq. (1990) (mental retardation); §22-52-1 et seq. (Supp. 1992) (mental illness); Alaska Stat. Ann. §47.30.700 et seq. (1990) (mental illness); Ariz. Rev. Stat. Ann. §36-533 et seq. (1986 and Supp. 1992) (mental illness); Ark. Code Ann. §20-48-404 (1991) (mental retardation); §20-47-207 (mental illness); Calif. Welf. & Inst. Code Ann. §6500 et seq. (West 1984 and Supp. 1993) (mental retardation); §5200 et seq. (mental illness); Colo. Rev. Stat. §27-10-105 et seq. (1989 and Supp. 1992) (mental illness); Conn. Gen. Stat. §17a-274 et seq. (1993) (mental retardation); §17a-495 et seq. (mental illness); Del. Code Ann., Tit. 16, §5522 (1983) (mental retardation); §5001 et seq. (1983 and Supp. 1992) (mental illness); D. C. Code Ann. § 6-1924, 6-1941 et seq. (1989) (mental retardation); §21-541 et seq. (mental illness); Fla. Stat. §393.11 et seq. (Supp. 1992) (mental retardation); §394.463,394.467 (1986 and Supp. 1992) (mental illness); Ga. Code Ann. § 37-4-40 et seq. (Supp. 1992) (mental retardation); §37-3-40 et seq. (1982 and Supp. 1992) (mental illness); Haw. Rev. Stat. § 334-60.2 et seq. (1985 and Supp. 1992) (mental illness); Idaho Code § 66-406 (1989) (mental retardation); § 66-329 (Supp. 1992) (mental illness); 111. Rev. Stat., ch. 91V2, ¶ 4-500 et seq. (1991) (mental retardation); ¶ 3-700 et seq. (mental illness); Ind. Code § 12-26-7-1 et seq. (Burns 1992) (mental illness); Iowa Code §222.16 et seq. (1987) (mental retardation); §229.6 et seq. (mental illness); Kan. Stat. Ann. § 59-2912 et seq. (1983 and Supp. 1990) (mental illness); Ky. Rev. Stat. Ann. §202B.040, 202B.100 et seq. (Michie 1991) (mental retardation); §202A.026, 202A.051 et seq. (mental illness); La. Rev. Stat. Ann. §28:404 (West 1989) (mental retardation); §28:54 et seq. (West 1989 and Supp. 1993) (mental illness); Me. Rev. Stat. Ann., Tit. 34-B, §5474 et seq. (1988) (mental retardation); §3864 (mental illness); Md. Health Code Ann. § 7-502 et seq. (1990) (mental retardation); § 10-613 et seq. (mental illness); Mass. Gen. Laws ch. 123, §5 et seq. (1989) (mental illness); Mich. Comp. Laws §330.1515 et seq. (1981) (mental retardation); §330.1434 et seq. (mental illness); Mo. Rev. Stat. §632.300 et seq. (1988) (mental illness); Mont. Code Ann. § 53-20-121 et seq. (1991) (mental retardation); §53-21-121 et seq. (mental illness); Neb. Rev. Stat. §83-1020 et seq. (1987 and Supp. 1992) (mental illness); Nev. Rev. Stat. §435.123 et seq. (1991) (mental retardation); §433A.200 et seq. (mental illness); N. H. Rev. Stat. Ann. § 171-A:10(II) (1990) (mental retardation); §135-C:34 et seq. (mental illness); N. J. Stat. Ann. §30:4-27.10 (West Supp. 1993) (mental illness); N. M. Stat. Ann. §43-1-13 (1989) (mental retardation); §43-1-10 et seq. (mental illness); N. Y. Mental Hyg. Law § 15.27 et seq. (McKinney 1988) (mental retardation); § 9.27 et seq. (mental illness); N. D. Cent. Code §25-03.1-07 et seq. (1989) (mental illness); Ohio Rev. Code Arm. §5123.71 et seq. (1989 and Supp. 1992) (mental retardation); § 5122.11 et seq. (mental illness); Okla. Stat., Tit. 43A, §5-401 (Supp. 1993) (mental illness); Ore. Rev. Stat. §427.215 et seq. (1991) (mental retardation); §426.070 et seq. (mental illness); Pa. Stat. Ann., Tit. 50, §4406 (Purdon 1969 and Supp. 1992) (mental retardation); § 7301 et seq. (mental illness); R. I. Gen. Laws § 40.1-22-9 et seq. (1990) (mental retardation); § 40.1-6-8 (mental illness); S. C. Code Ann. § 44-20-460 (Supp. 1992) (mental retardation); § 44-17-510 et seq. (1985) (mental illness); S. D. Codified Laws §27B-7-l et seq. (1992) (mental retardation); § 27A-10-1 et seq. (mental illness); Tenn. Code Ann. § 33-6-103 et seq. (Supp. 1992) (mental illness); Tex. Health & Safety Code Ann. § 593.041 et seq. (1992) (mental retardation); § 574.001 et seq. (mental illness); Utah Code Ann. §62A-5-312 (Supp. 1992) (mental retardation); §62A-12-234 (mental illness); Vt. Stat. Ann., Tit. 18, §8822 et seq. (1987) (mental retardation); §7612 et seq. (mental illness); Va. Code Ann. §37.1— 67.1 et seq. (1984 and Supp. 1992) (mental illness); Wyo. Stat. §25-5-119 (1990 and Supp. 1992) (mental retardation); §25-10-110 (mental illness).
But see Minn. Stat. §263B.07 et seq. (1992) (mental retardation and mental illness); Miss. Code Ann. §41-21-61 et seq. (Supp. 1992) (mental retardation and mental illness); N. C. Gen. Stat. § 122C-261 et seq. (1989 and Supp. 1992) (mental retardation and mental illness); Wash. Rev. Code §71.05.150 et seq. (1992 and Supp. 1993) (mental retardation and mental illness); W. Va. Code §27-6-2 et seq. (1992) (mental retardation and mental illness); Wis. Stat. §51.20 (1989-1990) (mental retardation and mental illness).
See Brief for New Jersey et al. as Amici Curiae 7, 1a.
Under a previous version of Kentucky's laws relating to the commitment of the mentally retarded, application by the parents or guardian of a mentally retarded person for placement in a mental retardation treatment center was treated as a voluntary commitment to which the procedural requirements of involuntary commitments were inapplicable. See Ky. Rev. Stat. Ann. §202B.040 (Michie 1982 and Supp. 1986). In a previous decision, the Court of Appeals held that persons committed upon application of parents or guardians must be considered to have been admitted involuntarily. Doe v. Austin, 848 F. 2d 1386, 1391-1392 (CA6 1988). We denied Kentucky's petition for certiorari from this decision, 488 U. S. 967 (1988), and Kentucky subsequently amended its statutes to remove this provision. In its brief, however, Kentucky again attacks this prior holding of the Court of Appeals. See Brief for Petitioner 20-28. Even were this issue not mooted by the repeal of the provision at issue, see, e. g., Department of Treasury v. Galioto, 477 U. S. 556, 559-560 (1986); Kremens v. Bartley, 431 U. S. 119, 128-129 (1977), it is not "fairly included" within the questions on which we granted certiorari, this Court's Rule 14.1(a). See Pet. for Cert. i.