Mr. Chief Justice Burger
delivered the opinion of the Court.
We granted certiorari to consider petitioner’s claim that the provisions of Title II of the Narcotic Addict Rehabilitation Act of 1966, 18 U. S. C. §§ 4251-4255, deny due process and equal protection by excluding from discretionary rehabilitative commitment, in lieu of penal incarceration, addicts with two or more prior felony convictions. The Circuits are in apparent conflict on this question. See the opinion of the Court of Appeals in this case, sub nom. Marshall v. Parker, 470 F. 2d 34 (CA9), and Watson v. United States, 141 U. S. App. D. C. 335, 439 F. 2d 442 (1970); United States v. Hamilton, 149 U. S. App. D. C. 295, 462 F. 2d 1190 (1972); United States v. Bishop, 469 F. 2d 1337 (CA1 1972); and Macias v. United States, 464 F. 2d 1292 (CA5 1972), cert. pending, No. 72-5539.
(1)
Petitioner, Robert Edward Marshall, pleaded guilty to an indictment charging him with entering a bank with intent to commit a felony, in violation of 18 U. S. C. § 2113 (a). At sentencing, petitioner requested that he be considered for treatment as a narcotic addict pursuant to Tit. II of the Narcotic Addict Rehabilitation Act of 1966 (NARA). The sentencing judge, after noting petitioner’s prior felony convictions for burglary, forgery, and possession of a firearm, concluded that the exclusion of persons with two prior convictions from the discretionary provisions of the Act as set forth in 18 U. S. C. § 4251 (f) (4) did not permit commitment under NARA. Petitioner was sentenced to 10 years’ imprisonment pursuant to 18 U. S. C. §4208 (a)(2), but the District Judge recommended that petitioner receive treatment for narcotics addiction while incarcerated.
Ten months after being sentenced, petitioner moved to vacate his sentence under 28 U. S. C. § 2255 on the ground that the two-prior-felony exclusion of NARA under § 4251 (f) (4) violates equal protection as embodied in the Due Process Clause of the Fifth Amendment.
The District Judge took note of Watson v. United States, supra, but declined to follow that holding. The District Judge also noted that there was no showing, as in Watson, supra, that petitioner’s prior convictions and his drug addiction were related and since his prior convictions did not relate to traffic in narcotics, the provisions of 18 U. S. C. § 4251 (f) (2) did not apply. The District Judge determined that, given the purposes of the statute, Congress had not acted arbitrarily in providing different disposition standards for convicted persons with records of prior felony convictions from those without such convictions, these classifications being related to eligibility for rehabilitative commitment under NARA.
The Court of Appeals viewed petitioner’s § 2255 petition as a motion under Rule 35 of the Federal Rules of Criminal Procedure for correction of an illegal sentence, and held the statutory classification constitutionally permissible, noting its disagreement with the decisions in Watson, supra, and United States v. Hamilton, supra. Viewing the Act in its entirety, the Court of Appeals concluded that Congress expressly limited the reach of the Act to addicts most likely to be rehabilitated through treatment and provided an exclusion as to convicted persons having two or more prior convictions.
Concluding there is no “fundamental right” to rehabilitation from narcotics addiction at public expense after conviction of a crime, and there being no “suspect” classification under the statutory scheme, the Court of Appeals considered the correct standard to be whether the statutory classification bore “some relevance to the purpose for which the classification is made.” Baxstrom v. Herold, 383 U. S. 107, 111 (1966); Dandridge v. Williams, 397 U. S. 471 (1970). The court reasoned that Congress adopted the challenged standards in an effort to restrict eligibility to those most likely to respond to treatment and held that Congress could not be said to have acted irrationally in so doing. The District Court's denial of petitioner’s motion to vacate his sentence was affirmed, 470 F. 2d 34 (CA9 1972). We granted certiorari, 410 U. S. 954 (1973). We agree with the District Court’s and the Court of Appeals’ reading of the statute and affirm.
(2)
Petitioner concedes that the concept of equal protection as embodied in the Due Process Clause of the Fifth Amendment, see Bolling v. Sharpe, 347 U. S. 497 (1954), does not require that all persons be dealt with identically, but rather that there be some “rational basis” for the statutory distinctions made, McGinnis v. Royster, 410 U. S. 263, 270 (1973), or that they “have some relevance to the purpose for which the classification is made.” Baxstrom v. Herold, supra, at 111; Rinaldi v. Yeager, 384 U. S. 305, 309 (1966). See also James v. Strange, 407 U. S. 128 (1972); Humphrey v. Cady, 405 U. S. 504 (1972). He argues that no such nexus exists under the classification provided by the challenged statute.
The broad purpose of Congress in enacting NARA, as set forth in the Act itself, was:
“[T]hat certain persons charged with or convicted of violating Federal criminal laws, who are determined to be addicted to narcotic drugs, and likely to be rehabilitated through treatment, should, in lieu of prosecution or sentencing, be civilly committed for confinement and treatment designed to effect their restoration to health, and return to society as useful members.” 42 U. S. C. § 3401.
See also H. R. Rep. No. 1486, 89th Cong., 2d Sess., 7 (1966), (“to provide for the treatment and rehabilitation of narcotic addicts when they are charged with or convicted of offenses against the United States”); S. Rep. No. 1667, 89th Cong., 2d Sess., 12 (1966). Congress recognized that some relationship between drug addiction and crime probably existed, and concluded that prosecution and imprisonment of all addicts, without more, would not cure addiction or retard the rising addiction rate, and that a rehabilitative rather than a purely penal aproach to the problem was called for. Id., at 13, 17.
It was not the purpose of Congress, however, to make every addict eligible for civil commitment simply by reason of addiction. The congressional intent in adopting the statutory exclusion based on prior convictions which is challenged here is somewhat less explicitly defined, but the objectives emerge clearly when the Act is read as a whole. Having recognized some nexus between drug addiction and crime, Congress specifically sought to insure that any program aimed at providing for the treatment of drug addiction wpuld not hinder traditional efforts to deal effectively with the strictly criminal aspects of the problem. The most explicit statement of congressional intent is found in the House Report:
“The practical effect of the implementation of the law provided for in the bill, is that strict punishment can be meted out where required to the hardened criminal, while justice can be tempered with judgment and fairness in those cases where it is to the best interest of society and the individual that such ■ a course be followed.
“The definition of ‘eligible individuar as set forth in the bill insures that the persons considered as candidates for civil commitment will not include criminals charged with violent crimes or be those whose records disclose a history of serious crimes.” H. R. Rep. No. 1486, pp. 9-10. (Emphasis supplied.)
Similarly, the Senate Report notes:
“The bill contains sufficient safeguards to assure adequate protection of the general public against the addict who is or may be a hardened criminal, while providing the flexibility necessary to enable Federal authorities to medically treat the addict who is capable of being cured and rehabilitated ....” S. Rep. No. 1667, p. 13.
It is quite clear that in adopting the two-prior-felony exclusion, Congress sought first, to exclude from NARA treatment those less likely to be rehabilitated by such treatment, and second, to exclude those whose records disclosed a “history of serious crimes.” The question we are called upon to decide is whether Congress could rationally have assumed that a person who has committed two or more prior felonies and is an. addict at the time sentence is to be imposed is likely to be less susceptible of rehabilitation by reason of his past record, thus posing a greater threat to society upon release.
Congress’ concern with susceptibility and suitability of multiple offenders to rehabilitative treatment can reasonably be said to derive from its belief that because of the nature of addiction treatment, one who had evidenced greater difficulty in conforming his behavior to societal rules and laws would himself be less likely to benefit from treatment. Additionally, such a person might also pose impediments to the successful treatment of others in the program. As testimony before both the House and Senate committees revealed, the treatment process for narcotics addiction is an arduous and a delicate undertaking, particularly in the aftercare stage when the subject is released into an unstructured environment which requires from the addict strict obedience to the limitations of the prescribed regime and full cooperation in the rehabilitative efforts.
The bill which emerged from conference included the two-prior-felony exclusion, and the report on that bill merely noted that “the conferees for the Senate felt it reasonable to exclude hardened offenders with serious criminal records and persons who have demonstrated their unsuitability for civil treatment.” 112 Cong. Rec. 27616 (1966).
Additionally, there is no generally accepted medical view as to the efficacy of presently known therapeutic methods of treating addicts and the prospect for the successful rehabilitation of narcotics addicts thus remains shrouded in uncertainty. Indeed, even the premise that drug addiction is one of the significant root causes of crime is not without challenge. See generally D. Musto, The American Disease: Origins of Narcotic Control (1973). See also American Bar Association and American Medical Association, Joint Committee on Narcotic Drugs, Drug Addiction: Crime or Disease? (1961). As testimony before the Congress revealed, no evidence to date has demonstrated more than a speculative chance for the successful rehabilitation of narcotics addicts. H. R. Rep. No. 1486, at 51. S. Rep. No. 1667, at 14. The NARA program was therefore fundamentally experimental in nature. See 112 Cong. Rec. 11896-11901 (1966). The suggestion that there is “obscurity” in the holding of this Court in Powell v. Texas, 392 U. S. 514 (1968), fails to take into account that when courts deal with problems in the administration of criminal law such as those related to drug addiction, alcoholism, mental disease, and the like, they are necessarily confined to the existing limits of human knowledge in those areas. As Mr. Justice Marshall noted in Powell:
“[T]he inescapable fact is that there is no agreement among members of the medical profession about what it means to say that ‘alcoholism' is a ‘disease.’ One of the principal works in this field states that . . . ‘alcoholism has too many definitions and disease has practically none.’ ” Id., at 522.
The holding in Powell was a candid acknowledgment that the medical uncertainties afford little basis for judicial responses in absolute terms.
When Congress undertakes to act in areas fraught with medical and scientific uncertainties, legislative options must be especially broad and courts should be cautious not to rewrite legislation, even assuming, arguendo, that judges with more direct exposure to the problem might make wiser choices. Accordingly, it would have been a permissible choice for Congress to permit discretionary inclusion in NARA programs of those whose prior offenses were determined to be addiction related or motivated. Such a discretion might appropriately have been vested in the trial judge much in the manner in which he is now required to exercise his discretion under § 4252 in determining whether the defendant is an addict who is likely to be rehabilitated through treatment. That Congress has not yet chosen to so provide, however, does not render constitutionally impermissible its decision to limit treatment to those with less than two prior felony convictions. Williamson v. Lee Optical Co., 348 U. S. 483 (1955); Dandridge v. Williams, 397 U. S. 471 (1970); McGowan v. Maryland, 366 U. S. 420 (1961); Jefferson v. Hackney, 406 U. S. 535 (1972).
It should be recognized that the classification selected by Congress is not one which is directed “against” any individual or category of persons, but rather it represents a policy choice in an experimental program made by that branch of Government vested with the power to make such choices. The Court has frequently noted that legislative classifications need not be perfect or ideal. The line drawn by Congress at two felonies, for example, might, with as much soundness, have been drawn instead at one, but this was for legislative, not judicial choice. McGinnis v. Royster, 410 U. S. 263 (1973); Powell v. Texas, supra, at 539-540 (Black, J., concurring). Against this background, it cannot be said that it was unreasonable or irrational for Congress to act on the predicate reflected in the legislative history and explicitly stated in the exclusion provision of § 4251 (f)(4), that a person with tvfo or more prior felonies would be less likely to adjust and adhere to the disciplines and rigors of the treatment program and hence is a less promising prospect for treatment than those with lesser criminal records.
In addition, Congress might rationally have sought to exclude from NARA treatment centers those it thought might be potentially disruptive elements within the sensitive environment of a drug treatment program. Nor can Congress be said to have acted without reason in determining that an addict with multiple convictions was more “hardened” and thus a greater potential danger to society on early release than the addict who had committed one prior felony or none.
Under NARA, Congress provided for comparatively lenient sentencing possibilities, but in excluding addicts with two prior felonies, it sought to assure that in an essentially experimental program to which limited resources were allocated these features would not be exploited by persons who were viewed by Congress as primarily antisocial and only secondarily addicts. In addition, since the fact of two prior felony convictions may be said to evidence a lesser susceptibility of deterrence, the reduced level of deterrence implicit in the benign policy of Title II could reasonably be thought by Congress to create an unacceptable risk to society and thus require the exclusion of such persons from NARA disposition.
We therefore hold that Title II of NARA, 18 U. S. C. §§ 4251-4255, does not constitute a denial of due process or equal protection by excluding from rehabilitative commitment, in lieu of penal incarceration, addicts with two or more prior felony convictions.
Affirmed.
Title 18 U. S. C. § 4253 (a) provides in relevant part that:
“Following the examination provided for in section 4252, if the court determines that an eligible offender is an addict and is likely to be rehabilitated through treatment, it shall commit him to the custody of the Attorney General for treatment under this chapter . . .
Title 18 U. S. C. §4251 (f) provides that:
“(f) 'Eligible offender’ means any individual who is convicted of an offense against the United States, but does not include—
“(1) an offender who is convicted of a crime of violence.
“(2) an offender who is convicted of unlawfully importing or selling or conspiring to import or sell a narcotic drug, unless the court determines that such sale was for the primary purpose of enabling the offender to obtain a narcotic drug which he requires for his personal use because of his addiction to such drug.
“(3) an offender against whom there is pending a prior charge of a felony which has not been finally determined or who is on probation or whose sentence following conviction on such a charge, including any time on parole or mandatory release, has not been fully served: Provided, That an offender on probation, parole, or mandatory release shall be included if the authority authorized to require his return to custody consents to his commitment.
“(4) an offender who has been convicted of a felony on two or more prior occasions.
“(5) an offender who has been committed under title I of the Narcotic Addict Rehabilitation Act of 1966, under this chapter, under the District of Columbia Code, or under any State proceeding because of narcotic addiction on three or more occasions.”
Title 18 U. S. C. § 4251 (d) defines “felony” for purposes of the Act to include
“any offense in violation of a law of the United States classified as a felony under section 1 of title 18 of the United States Code, and further includes any offense in violation of a law of any State, any possession or territory of the United States, the District of Columbia, the Canal Zone, or the Commonwealth of Puerto Rico, which at the time of the offense was classified as a felony by the law of the place where that offense was committed.”
Prisoners not eligible for treatment under NARA may receive the benefit of programs comparable to those provided under NARA, available to narcotics addicts under administrative processes of the Federal Bureau of Prisons. See generally Drug Abuse Programs Manual, Bureau of Prisons Policy Statement No. 8500.1 (Apr. 20, 1973).
Because the two-prior-felony convictions in Watson were for violations of narcotics laws, there was some conjecture that the rationale of that ease was limited to its facts. In United States v. Hamilton, 149 U. S. App. D. C. 295, 462 F. 2d 1190 (1972), the Court of Appeals for the District of Columbia Circuit, the same court which decided Watson, dispelled all doubt by holding the two-prior-felony exclusion to be unconstitutional where the defendant has been convicted of one prior narcotics law felony and four prior non-narcotics felony offenses. Subsequently, in United States v. Bishop, 469 F. 2d 1337 (1972), the Court of Appeals for the First Circuit also held the exclusion of § 4251 (f) (4) to be unconstitutional where the prior felonies were non-narcotics violations.
In 1966, Congress enacted the Narcotic Addict Rehabilitation Act, Pub. L. 89-793, 80 Stat. 1438. Title I of the Act, 28 U. S. C. §§ 2901-2906, provides for civil rehabilitative commitment prior to trial of persons charged with federal crimes, and dismissal of the charges upon successful completion of the treatment. Title II, 18 U. S. C. §§ 4251-4255, provides for similar commitment in lieu of imprisonment for those convicted of a federal crime. Title III, 42 U. S. C. §§ 3411—3426, provides for civil commitment of persons not involved in the criminal process. In each case, the court must, after ordering commitment for examination, determine whether the individual is an addict, as defined by the statute, 28 U. S. C. § 2901 (a), 18 U. S. C. § 4251 (a), 42 U. S. C. § 3411 (a), and whether he “is likely to be rehabilitated through treatment,” 28 U. S. C. § 2902 (b), 18 U. S. C. § 4253 (a), 42 U. S. C. § 3415.
The Act was based on the House-passed Administration bill, H. R. 9167. The two-felony exclusion is derived from that bill, which contained all five of the final exclusions in some form. All of the other House bills considered by the House Committee, but one, also had a two-felony exclusion. See Civil Commitment and Treatment of Narcotic Addicts, Hearings on H. R. 9051, 9159, 9167 and Related Bills before Subcommittee No. 2 of the House Committee on the Judiciary, 89th Cong., 1st and 2d Sess., ser. 10, pp. 1-14, 17, 20-53 (1965 and 1966). The Senate bill, S. 2191, did not, however, contain the two-felony exclusion, see S. Rep. No. 1667, 89th Cong., 2d Sess., 7-8 (1966). In conference, where Titles I and II of the House bill were adopted, the two-felony exclusion was incorporated into the final bill. See H. R. Conf. Rep. No. 2316, 89th Cong., 2d Sess., 2-3, 6 (1966); 112 Cong. Rec. 27616 (1966).
“After carefully considering the proposed legislation, as amended, the committee finds that it offers a flexible and logical means to provide for the treatment of drug addicts who are likely candidates for rehabilitation without essentially changing the authority of law enforcement officials and the courts to enforce full criminal actions in appropriate cases." S. Rep. No. 1667, p. 37. (Emphasis supplied.)
Though actually discussing the definition of “eligible individuals” contained in Title I, concerning civil commitment prior to trial, the identical definitions are contained in Title II, and the House Report indicates that there is no difference between the rationale or the language of the various provisions. See H. R. Rep. No. 1486, 89th Cong., 2d Sess., 12, 20 (1966).
Prior to inclusion of the two-prior-felony exclusion, the Senate Report described the purposes of the restrictions on eligibility by stating:
“The net effect is to confine eligibility for the benefits of the legislation to addicts accused of nonviolent crimes who- show good prospects for rehabilitation, while retaining strict criminal punishment for dangerous or hardened offenders, narcotics pushers, and persons with a history of failure to respond to treatment.” S. Rep. No. 1667, p. 17.
The Senate Report states:
“The process is extremely complex and difficult, involving sustained therapy, principally psychiatric, and perhaps a return to the community in stages, utilizing short visits, a halfway house, a work camp, or some similar facility. ... In addition, some sanction should be available to enforce the cooperation of the addict in the post-hospitalization period.” S. Rep. No. 1667, p. 15.
Some criticism has been directed at the cautious use of the NARA program. See Report by the Comptroller General of the United States to the Congress, Limited Use of Federal Programs to Commit Narcotic Addicts for Treatment and Rehabilitation (1971).
Similarly rational was the related congressional choice to give priority of treatment to convicted addicts at an early stage in their lives. Although not invariably so, those with no felony record may well be younger, as a group, than those with multiple convictions, and this notwithstanding that the median age of serious offenders has shown a steady downward trend.
Virtually all drug treatment programs include group therapy and involve extensive personal interaction among those in the treatment program. In addition, there are strict institutional rules regarding virtually every aspect of the addict's daily existence which he is expected to follow, and the existence of such authority is considered vital to successful treatment, both in the program itself, and particularly during the aftercare period. See Cole, Report on the Treatment of Drug Addiction, Task Force Report: Narcotics and Drug Abuse, The President’s Commission on Law Enforcement and Administration of Justice 135-147 (1967); Petersen, Yarvis & Farkas, The Federal Bureau of Prisons Treatment Program for Narcotics Addicts (1969); Federal Drug Abuse Programs, A Report Prepared by the Task Force on Federal Heroin Addiction Programs and Submitted to the Criminal Law Section of the American Bar Association and the Drug Abuse Counsel 241-278, 393-416 (1972); Vaillant & Rasor, The Role of Compulsory Supervision in the Treatment of Addiction, 30 Fed. Prob. 53-59 (June 1966).
Under 18 S. C. § 4253, an individual who is determined to be eligible for NARA treatment is to be committed to the custody of the Attorney General for treatment for “an indeterminate period of time not to exceed ten years, but in no event shall it exceed the maximum sentence that could otherwise have been imposed.” Title 18 S. C. § 4254 then allows for conditional release of an offender, upon the requisite determination, any time after the offender has received six months’ treatment. Thereafter, he is legally on parole under the jurisdiction of the Board of Parole, 18 U. S. C. § 4255.
See 112 Cong. Rec. 11813 (1966).