PELL, Circuit Judge.
This is an appeal from the entry of a preliminary injunction by the District Court for the Western District of Wisconsin enjoining Wilbur J. Schmidt, the Secretary of the Department of Health and Social Services of the State of Wisconsin, and his agents from restricting correspondence between Juan Morales and his wife’s sister.1 According to Morales’s complaint, defendant-appellant Schmidt has general supervision over the rulemaking policies of the state prisons and is “directly liable for the conduct and actions of his agents therein.” At the time of the filing of the complaint, Morales was an inmate of the Wisconsin State Prison at Waupun.
As an initial matter, we must dispose of a mootness question. Morales was convicted of having violated the Uniform Narcotics Drug Addiction Act and was sentenced to a term of not more than ten years. On March 27, 1972, before the district court entered its order in this case, Morales was released on parole. The petition of amicus curiae, Corrections Legal Services Program, suggests that the case is therefore moot. We agree with the appellant and appellee that we have before us a live controversy. The department which defendant Schmidt heads has responsibility for the entire correctional system of the State of Wisconsin, including the administration of parole and probation matters. Pursuant to the sentence imposed on Morales, Schmidt will have legal custody of the plaintiff, although a parolee, for six more years and has authority to impose restrictions upon him. In his response to the amicus curiae petition, Secretary Schmidt stated that he has refrained from preventing Morales from communicating with his sister-in-law solely because of the duty to comply with the district court’s injunction. We further note that there is always the possibility that Morales during his period of parole will violate the terms of his conditional release and thus be returned to prison. In light of these circumstances, we find that the change in plaintiff’s status does not alter the central issue.
I
The parties are in agreement about the facts. On November 28 or 29, 1970, [1337]*1337Morales wrote a letter to his wife’s sister, Kathleen Steffes, who was on the prison’s list of approved correspondents. In the letter Morales mentioned that he was the father of a child by Steffes and stated that he hoped to continue his relationship with mother and son in the future. At the time the letter was written, the plaintiff’s wife was apparently unaware of the relationship between her sister and Morales, including the fact that her husband had fathered Steffes’s illegitimate child.
Prison administrators intercepted and read the letter and then routed it to Morales’s prison social worker, who refused to mail it to Steffes. On December 22, 1970, he discussed with Morales the letter as well as Morales’s continued correspondence with his sister-in-law. After consulting with prison officials, the social worker told Morales that Steffes was being placed on the list of denied correspondents-visitors and that she would be notified of this decision.
Both Morales and Steffes were advised that the decision would be re-evaluated if they could provide additional information.
The prison administrators based their actions on their opinion that it would be inappropriate to permit Morales to correspond with a woman with whom he had had an illicit sexual relationship, particularly since they had reason to believe that he intended to continue the relationship upon his release from prison although he also intended to live with his wife and their children.
Neither Morales nor Steffes made further efforts to justify to prison authorities their correspondence. In January 1971, Morales filed the present Section 1983 action, 42 U.S.C. § 1983, in the federal district court, alleging that, the prison officials’ actions in refusing to allow the letter of November 28, 1970, to be sent to Kathleen Steffes and in refusing to permit him to correspond with her violated his rights under the First, Fifth, Ninth, and Fourteenth Amendments. Condemning the administrators’ actions as “arbitrary, capricious and unreasonable,” he sought a permanent injunction against the defendant and his agents to bar them from depriving him of the use of the mails “to communicate with [plaintiff’s] relatives and family.” Morales also alleged irreparable injury and moved for a temporary restraining order.
The district court entered an order directing the Secretary of Health and Social Services to show cause why the requested order should not be granted. The Secretary then moved for summary judgment upon affidavits.
On April 6, 1972, the court dismissed the motion for summary judgment and entered the preliminary injunction challenged here. In reaching its decision, the court reasoned as follows: (1) freedom to use the mails is a First Amendment freedom; (2) someone not convicted of a crime would be free to correspond with his wife’s sister whether or not he had been sexually intimate with her; (3) the interest of a non-convict in corresponding by mail is a “fundamental” interest; (4) “when the government undertakes to deny this freedom .to a member of the class of persons who have been convicted of crime, while granting it to members of a class of persons who have not been convicted of crime, the burden is upon the [State] to show a compelling governmental interest in this differential in treatment,” 340 F.Supp. at 554-555; and (5) the Government’s interests in the maintenance of internal prison discipline and in the rehabilitation of Morales are not so compelling as to permit their vindication by interference with a right secured to plaintiff by the First and Fourteenth Amendments.
II
The Constitution provides no clear answer to federal courts seeking to determine the civil rights of state prisoners. The variety of views expressed by the courts when resolving challenges by prisoners to the constitutionality of prison rules reflects the ambiguous mandate [1338]*1338of the Bill of Rights and the Thirteenth and Fourteenth Amendments when construed together.
The Thirteenth Amendment, if read literally, suggests that the States may treat their prisoners as slaves: “Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.”2 However, by emphasizing the applicability to state prisoners of the Fourteenth Amendment, which now incorporates most of the Bill of Rights including the Eighth Amendment’s prohibition -of “cruel and unusual punishments,”3 courts in recent years have moderated the harsh implications of the Thirteenth Amendment. But the tension remains between the view that a prisoner enjoys many constitutional rights, which rights can be limited only to the extent necessary for the maintenance of a person’s status as prisoner (or parolee), and the view that a prisoner has only a few rudimentary rights and must accept whatever regulations and restrictions prison administrators and State law deem essential to a correctional system. Even the most “liberal” opinions acknowledge that although a convicted person is not a slave neither is he a “freeman.”
Thus, we agree with the district court that state prisoners’ suits present exceedingly perplexing problems for the federal courts.4 We must not shirk our [1339]*1339duty to protect an individual’s rights, yet we must respect the rights and interests of the States. In a symposium on prison reform and “prisoners’ rights,” the Dean of the University of Virginia Law School articulated well the major questions:
“What is the proper function of the coui’ts, the legislatures and executive? What are the limits of the wisdom and power of each? What must be left to administrators for determination? What are the opportunities of each of these institutions for information gathering, for enforcement, and for promulgation? . How much liberty is compatible with the order necessary in any kind of institutional confinement — a closed society- — where the principal concern of each inmate is to get out?
What are the programs which in fact change the character of human beings? . . . [W]hat kinds of things does the Constitution require [in a prison setting?]” 5
The Fourteenth Amendment states in part: “nor shall any State deprive any person of life, liberty, or property, without due process of law.” Morales does not maintain that his conviction and sentence were accomplished without due process. But this does not establish what liberties remained to him once he was found guilty according to law. The relatively few cases in which prisoners have contested prison officials’ refusal to permit correspondence or visiting rights with specific persons are of limited aid.6 Factually closest is Fussa v. Taylor, 168 F.Supp. 302 (M.D.Pa.1958), where the court upheld the warden’s decision. However, there the forbidden female correspondent was deeply involved in narcotics, was herself an inmate, and was but the most recent in a series of paramours the petitioner had had. In Corby v. Conboy, 457 F.2d 251 (2d Cir. 1972), decided after the Second Circuit’s seminal opinion in Sostre v. McGinnis, 442 F.2d 178 (2d Cir. 1971), cert. denied, 404 U.S. 1049, 92 S.Ct. 719, 30 L.Ed.2d 740 (1972), a Second Circuit pan[1340]*1340el held that the contention that prison administrators had violated the prisoner’s civil rights by refusing to mail several letters to the petitioner’s family because they contained prison news or constituted “begging” adequately stated a claim under Section 1983. Another Second Circuit decision, Wilkinson v. Skinner; 462 F.2d 670 (2d Cir. 1972), affirmed the dismissal of a prisoner’s civil rights complaint because the issues raised therein had been mooted by amended regulations relating to censorship of prison correspondence. The new regulations, which allowed prison authorities to refuse to mail outgoing letters or to accept incoming mail “where it is apparent that there exists a clear and present danger to the jail or penitentiary,” provided a sufficiently precise delineation of the boundaries of the protection against censorship. Accordingly, the court concluded that “[ajbsent a showing that appellant’s correspondence with his mother . . . would pose a clear and present threat to prison discipline or security, presumably such correspondence will not be further interfered with by the appellees,” 462 F.2d at 672-673.7
Unlike Wilkinson, our case does not involve a regulation that embodies a familiar legal standard. Pursuant to statutory authority, Wisconsin prison officials had promulgated correspondence rules, and defendant Schmidt on appeal states that his agents, in terminating correspondence between Morales and his sister-in-law, acted under them. (See Appendix to this opinion.) However, the regulations provided no standard comparable to the one approved in Wilkinson. Furthermore, the enabling legislation specifies no guidelines for the drafting of rules governing correspondence. The formulation of parole regulations apparently is also left to the discretion of correctional administrators. The district court therefore did not discuss particular written regulations but tackled directly the problem of determining the appropriate standard for testing whether the Constitution forbids a State to regulate the life of a convicted person in a certain manner. Its choice of standard was intertwined with its analysis of the constitutionality of a State’s limiting communications by a person convicted of a crime under circumstances where the State could not so limit a non-convict’s communications.
It is to this portion of the district court’s, opinion, its adoption of the “compelling state interest” standard, that appellant Schmidt takes greatest exception. Schmidt fears that if we. uphold the ap[1341]*1341plicability of the test, few prison regulations will be able to withstand constitutional attack. Prisoners allegedly will contest every disciplinary measure, and prison administrators will be unable to command the adherence to rules which allows the correctional system to function smoothly.
The compelling state interest standard is one of several “tests” courts use to determine whether governmental curbs on a citizen’s civil liberties are justifiable. See, e. g., Bates v. City of Little Rock, 361 U.S. 516, 524, 80 S.Ct. 412, 417, 4 L.Ed.2d 480 (1960). “Where there is a significant encroachment upon personal liberty, the State may prevail only upon showing a subordinating interest which is compelling.” As the opinion of the district court below illustrates, how stringent a justification a State must offer depends in part, under current doctrine, on the nature of the right invaded. Courts commonly reserve the compelling state interest standard for impingements on sensitive areas of liberty, that is, interests of a citizen which courts deem “fundamental.”
Like many other judicial standards, “compelling state interest” is not a precise concept. Some judges, for example, seem to equate it with the “less drastic means” test. Others, like Mr. Justice White, rephrase it as a curtailment “reasonably necessary for the effectuation of a legitimate and substantial state interest, and not arbitrary or capricious in application. . . .” Griswold v. Connecticut, 381 U.S. 479, 502, 504, 85 S.Ct. 1678, 1692, 14 L.Ed.2d 510 (1965) (White, J., concurring in the judgment finding Connecticut’s statutory ban of contraceptives unconstitutional). Cf. Branzburg v. Hayes, 408 U.S. 665, 700-708, 92 S.Ct. 2646, 33 L.Ed.2d 626 (1972).
The district court in the case before us decided that correspondence by mail is a “fundamental” interest. Cf. Lamont v. Postmaster General, 381 U.S. 301, 85 S.Ct. 1493, 14 L.Ed.2d 398 (1965), especially the concurring opinion of Mr. Justice Brennan, 381 U.S. at 308, 85 S.Ct. 1493. Hence, the district court concluded that the compelling state interest standard was the appropriate test for judging the constitutionality of governmental restrictions on correspondence by mail. The district court noted that the equal protection clause is clearly applicable to intra-prison classes. The court, however, then rejected the “unar-ticulated but potent” view that the equal protection clause has no applicability where the classes involved consist of prisoners and non-prisoners. The court adopted the thesis that those convicted of crime should continue “to share with the general population the full latent protection of the Fourteenth Amendment.” 340 F.Supp. at 549.
In so holding, the district court did not condemn the establishment of the two classes as “inherently suspect.” Instead, it ruled that when a State seeks to restrain a fundamental interest of the members of one class, it bears the burden of showing a compelling interest in the differential in treatment. The State may not merely show that the differentiation was not arbitrary or unreasonable.8
[1342]*1342We disagree that the equal protection clause mandates the elimination of the distinction between the two classes here. The Supreme Court has indicated that the constitutional limitations on governmental actions differ depending on the role in which the government is acting in a particular case. This is so despite the fact that each situation might involve the same constitutional interest of the affected individuals. See, e. g., Tinker v. Des Moines Independent Community School District, 393 U.S. 503, 506, 89 S.Ct. 733, 21 L.Ed.2d 731 (1969); Pickering v. Board of Education, 391 U.S. 563, 88 S.Ct. 1731, 20 L.Ed.2d 811 (1968). Cf. the Supreme Court’s statement in Morrissey v. Brewer, 408 U.S. 471, 92 S.Ct. 2593, 33 L.Ed. 2d 484 (1972): “Revocation [of parole] deprives an individual, not of the absolute liberty to which every citizen is entitled, but only of the conditional liberty properly dependent- on observance of special parole restrictions. The State has found the parolee guilty of a crime against the people. That finding justifies imposing extensive restrictions on the individual’s liberty. . . .” 408 U.S. at 480, 483, 92 S.Ct. at 2600, 2601. The Morrissey Court did not pass on the constitutionality of the restrictions placed on parolees; however, in describing, the “traditional” conditions of parole, including the prohibition of association or correspondence with certain categories of undesirable persons, the Court implicitly acknowledged the propriety of these conditions or, at least, the authority of the States to limit a parolee’s activities substantially beyond the ordinary restrictions imposed by law on an individual citizen. As we suggested before, the Constitution gives the States considerable leeway in deciding how to treat persons convicted of violating State law. We hold that the Constitution does not require a State to show a compelling interest when it seeks to restrict a prisoner’s or parolee's associations or written communications with persons who are not judges, lawyers, or governmental officials. (See footnote 6, supra.)
Defendant Schmidt apparently opposes any judicial inquiry into the reasonableness of specific restrictions concerning a particular felon. He deplores the erosion of the “hands-off” doctrine, which provided that a court should not examine the legitimacy of prison rules or the reasonableness of their application in a particular situation, areas entrusted to the discretion of prison officials.
Secretary Schmidt also urges us to find that the kind of restriction imposed on Morales is “inherent in the concept of punishment for a crime.” Although some courts have referred to conditions “inherent” in a system of punishment, we think that such an inquiry is unwise. It would plunge us into a philosophical debate far removed from our proper judicial function of interpreting and applying the Constitution. Further, a decision based on our understanding of “punishment” would merely reflect our personal predilection for certain social and moral policies, e. g., retribution or utilitarianism.
In our opinion, courts have been wisely hesitant about involving themselves too deeply in the day-to-day operations of a state penal system. Prison administrators necessarily must have freedom to exercise discretion in the execution of their duties. However, to allow prison administrators to determine the constitutional rights of a convicted person would be to abdicate our responsibilities. Cf. Johnson v. Avery, 393 U.S. 483, 486, 89 S.Ct. 747, 21 L.Ed.2d 718 (1969); Sobell v. Reed, 327 F.Supp. 1294, 1302 (S.D.N.Y.1971). After all, the maintenance of a correctional system is state action. “Federal courts sit not to supervise prisons but to enforce the constitutional rights of all ‘persons’ which in-[1343]*1343elude prisoners.” Cruz v. Beto, 405 U.S. 319, 321, 92 S.Ct. 1079, 1081, 31 L.Ed.2d 263 (1972). Recent decisions of the United States Supreme Court, as well as of several courts of appeals, clearly establish that cursory disposition of un-frivolous claims by prisoners no longer suffices. In evaluating a prisoner’s suit, the Wisconsin Supreme Court recently stated: “The courts cannot upon a hands-off doctrine exercise ‘abstention’ when the constitutionality of the administration’s act is at issue.” State ex rel. Thomas v. State, 55 Wis.2d 343, 357, 198 N.W.2d 675, 683 (1972).
The appropriate standard by which to judge the constitutionality of the kind of restriction the defendant wishes to impose in this ease is the usual one for analyzing State action, namely, whether the action contemplated bears a rational relationship to or is reasonably necessary for the advancement of a justifiable purpose of the State. Pursuant to this standard, a district court should scrutinize closely the justifications offered by the State for the limitation. Its review must “be more than an obeisance to a warden’s asserted expertise.” Spaeth, The Courts’ Responsibility for Prison Reform, 16 Vill.L. Rev. 1029, 1031, 1037 (1971). In State ex rel. Thomas v. State, supra, the Wisconsin Supreme Court interpreted the statute under which defendant Schmidt claims his agents acted.9 The court indicated that it would condemn the statute as unconstitutional if it prohibited totally communication by inmates:
“This statute may be read to require reasonable regulations which effectuate legitimate administrative objectives without infringing the first amendment rights of prisoners. The statute certainly does not grant all the powers of an absolute censor to the department of health and social services.” 55 Wis.2d at 357, 198 N.W.2d at 682-683.
Cf. Hyland v. Procunier, 311 F.Supp. 749, 750 (N.D.Cal.1970):
“ [I] t is not only the apparent abridgement of first amendment rights which concerns the Court. California as well as federal law has imposed the due process rule of reasonableness upon the State’s discretion in granting or withholding ‘privileges’ from prisoners, parolees, and probationers. . . . The defendants herein have made no showing that the condition imposed on plaintiff’s parole is in any way related to the valid ends of California’s rehabilitation system.”
Our adoption of the rational relationship standard is consistent with the Wisconsin Supreme Court’s opinion in State ex rel. Thomas v. State, supra. The appellant there, an inmate of the Wisconsin State Prison at Waupun, sought, inter alia, an injunction restraining interference by prison officials with his attempt to communicate with the Veterans Administration. The court reversed the dismissal of the prisoner’s suit, citing two theories: the right to petition for redress of grievances and the First Amendment’s free-speeeh guarantee. We note that the court’s free speech discussion was an alternative ground for its decision. Further, the court’s primary aim was to emphasize the State’s obligation to justify its actions under any of the accepted standards of review, 55 Wis.2d at 353, 356-357, 198 N.W.2d at 682-683. We do not read the opinion as committing the Wisconsin Supreme court to any one particular standard.
The district court’s granting of a preliminary injunction was based upon the “compelling state interest” standard which we hold not to be applicable in the situation before the court. The record is insufficient for a determination of the question of whether the State’s proposed restriction is justified under the rational relationship standard, the test [1344]*1344which we hold is applicable here. We accordingly reverse and remand for further proceedings not inconsistent with this opinion. Upon remand, it will be appropriate to consider, inter alia, whether the prohibition of Morales’s communicating and associating with his sister-in-law is rationally related to the advancement of some legitimate purpose of the State such as the rehabilitation of Morales.
Reversed and remanded.
APPENDIX TO THE COURT’S OPINION
Wis.Stat. § 53.09 states:
“Labor and Communications. Inmates shall be employed as provided in chapter 56. Communication shall not be allowed between inmates, and any person outside the prison except as prescribed by the prison regulations.”
Pursuant to this authority, the Division of Corrections promulgated regulations governing the delivery and dispatch of prisoner correspondence. The administrative regulations covering mail privileges, revised as of February, 1971, provide in pertinent part:
“(a) Approved Lists. Each inmate shall be permitted to correspond with approved persons named on the correspondence list. . . . The list of approved correspondents may be changed or revised with approval of the appropriate officer.
(b) Limitations. The number of outgoing letters permitted each week shall be specified by the warden or superintendent. The outgoing correspondence privilege may be withdrawn or restricted as a disciplinary or security measure.
(c) Mail Inspection. All incoming and outgoing mail for inmates shall be subject to institution inspection. At the discretion of the warden, superintendent, or designated official, the delivery or dispatch of any inmate correspondence, with the exceptions noted [letters to certain state officials and to judges], may be withheld for reasons of propriety, security or the welfare of the institution or inmate. Such correspondence shall be disposed of as the warden or superintendent shall direct, having in mind the best interests of the inmate and the institution. . . .”
In November 1971 and March 1972, certain changes were made in the correspondence regulations. Approved and denied correspondence lists were continued, but limitations on the number of correspondents and the number of letters permitted were removed. Further, except for prisoners in disciplinary segregation, “all outgoing mail [that is not visibly unusual because of size, etc.] shall be sealed by the individual and shall not be read by the institution staff.” Also, “[a] 11 incoming mail will be opened and inspected for contraband but the letter shall not be read.” The new regulations state that an institution warden or superintendent may suspend privileges (a) for violators or correspondence rules; (b) for any person whose behavior or attitude poses a threat to the safety and welfare of the institution; and (c) at a time of general threat to the overall security of the institution.