I.
On November 19, 1975, Vincent Molina pled guilty to distribution of heroin. He was given a five year prison term and a three year special parole term. After serving three years of his sentence, Molina was paroled on December 13, 1978. One condition of his release was that he attend a drug treatment program. He failed to follow this requirement and was placed in a halfway house in the fall of 1979. He did not attend therapy sessions at the halfway house and was found to be in violation of the house rules on December 18, 1979. On this same day, Molina’s parole officer informed him that a parole revocation hearing had been requested. On December 20 Molina left the halfway house and did not return. He had discussions with the parole authorities about surrendering, but he did not do so. A warrant was issued for Molina to be retaken and he was arrested and imprisoned on March 10, 1980, for violating the conditions of his parole. Molina had a preliminary interview with a parole officer on March 19, 1980. This hearing resulted in a finding of probable cause on one charge of violating parole conditions. Molina’s final parole revocation hearing was held on May 1, 1980. On May 27, 1980, the Parole Commission found that a parole violation had occurred, but returned Molina to the supervision of his parole officer.
On March 17, 1980, after he had been imprisoned, Mr. Molina filed a petition for a writ of habeas corpus in federal district court. In the petition he alleged that: (1) he had not violated his parole conditions; (2) his parole officer had made misrepresentations to make it appear that Molina had violated his parole conditions; (3) his parole officer continually harassed Molina; and (4) Molina had not been given enough time to appeal the decision to commit him to the halfway house. On March 20, 1980, the district court held a hearing on the petition. Although the district court stated that it would not consider the merits of Molina’s parole revocation, it did find that it had jurisdiction under the habeas statute to entertain a request for bail by an arrested parolee. The district court then ordered Molina released on a personal recognizance bond.
It is important to note that Molina sought no change in the revocation procedures, nor did his petition raise any constitutional or statutory objections to those procedures. The government appealed the grant of bail, asserting that the district court lacked the power to order bail for a parolee who is incarcerated pending revocation; or that even if the district court did have such power, it was improperly exercised here.
Two potential jurisdictional problems are presented. The first is whether such a bail order is final and therefore appealable. See 28 U.S.C. §§ 1291, 2253; Stachulak v. Coughlin, 520 F.2d 931, 933 (7th Cir. 1975), cert. denied, 424 U.S. 947, 96 S.Ct. 1419, 47 L.Ed.2d 354 (1976). Mr. Molina was claiming only the right to be released during the pendency of revocation proceedings. He was awarded the relief he sought. Neither he nor the district court contemplated any further action on the petition. Under these circumstances there was a final order in the habeas corpus proceeding and this Court has jurisdiction to consider the appeal.1
The second and more perplexing jurisdictional problem is that of mootness. The Parole Commission argues that even if the issue presented here is moot as to Molina, it is “capable of repetition, yet evading *74review,” and therefore can be decided, although technically moot. See Securities & Exchange Commission v. Sloan, 436 U.S. 103, 109, 98 S.Ct. 1702, 1707, 56 L.Ed.2d 148 (1978). To come within this rule the challenged action must be too short in duration to be fully litigated prior to its cessation and there must be an expectation that the complaining party will again be subjected to the protested action. Board of Trade v. Commodity Futures Trading Commission, 605 F.2d 1016, 1020 (7th Cir. 1979), cert. denied, - U.S. -, 100 S.Ct. 1866, 64 L.Ed.2d 281 (1980).
Mr. Molina’s revocation proceedings are over, and it appears very likely that in most cases the revocation process will have run its course before full review of a bail order, including a possible appeal to the Supreme Court, could be obtained. Typically, then, bail orders will be too short in duration to be fully litigated before they expire. The second requirement is clearly met here. The Parole Commission states that it is repeatedly presented with this problem. It can reasonably be expected that parolees will continue to seek bail from the courts if they believe it will be granted even when the Commission refuses to release them before a revocation hearing.2
II.
Morrissey v. Brewer, 408 U.S. 471, 92 S.Ct. 2593, 33 L.Ed.2d 484 (1972), held that the due process clauses of the United States Constitution require that certain minimum procedures be followed when parole is revoked. See also Gagnon v. Scarpelli, 411 U.S. 778, 93 S.Ct. 1756, 36 L.Ed.2d 656 (1973). In 1976, Congress, through the Parole Commission and Reorgánization Act, 18 U.S.C. §§ 4201, et seq., revamped the parole system for federal prisoners. 18 U.S.C. §§ 4213-15 contain provisions relating to parole revocation. The United States Parole Commission has also issued regulations regarding revocation proceedings. See 28 C.F.R. §§ 2.44, et seq.
If a parolee is alleged to have violated his parole the Commission under § 4213 may either summon the parolee to a § 4214 revocation hearing or issue a warrant and retake the parolee. See 28 C.F.R. § 2.44. Of course, the question of release arises only when the Commission elects to retake and incarcerate the parolee. See 28 C.F.R. § 2.49(d). Section 4214(a)(1)(A) provides that the parolee is entitled to a “preliminary hearing . . . without unnecessary delay,3 to determine if there is proba*75ble cause to believe that he has violated a condition of his parole.!’ The parolee is informed at the end of the hearing whether probable cause is believed to exist. 28 C.F.R. § 2.48(d). If probable cause is found, § 4214(a)(l)(A)(i-iv) states that the Commission:
“may restore any parolee to parole supervision if:
(i) continuation of revocation proceedings is not warranted; or
(ii) incarceration of the parolee pending further revocation proceedings is not warranted by the alleged frequency or seriousness of such violation or violations;
(iii) the parolee is not likely to fail to appear for further proceedings; and
(iv) the parolee does not constitute a danger to himself or others.”4
It is apparent that Congress intended to give the Parole Commission great latitude in making decisions relative to revocation. In fact, 18 U.S.C. § 4218(d) states that:
“Actions of the Commission pursuant to paragraphs (1), (2), and (3) of section 4203(b) shall be considered actions committed to agency discretion for purposes of section 701(a)(2) of title 5, United States Code.”
Section 4203(b)(3) provides that:
“The Commission, by majority vote, and pursuant to the procedures set out in this chapter, shall have the power to—
* * * * * j *
(3) modify or revoke an order paroling any eligible prisoner.”
Chapter 7 of title 5 of the United States Code governs judicial review under the Administrative Procedure Act. 5 U.S.C. § 701(a)(2) states that “This chapter applies except to the extent that — . (2) agency action is committed to agency discretion by law.” The effect of § 4218(d) is therefore to insulate all Commission decisions relating to parole revocation from judicial review under the APA. This includes the Commission’s decision to retain a retaken parolee in prison pending final action on revocation of his parole.
The exclusion of judicial review under the APA does not completely eliminate the possibility of habeas corpus relief,5 but it does indicate that courts must grant *76such relief only in extremely limited circumstances. Although the writ of habeas corpus is available to any person in federal custody, 28 U.S.C. § 2241(c)(1), the purpose of the writ is to provide a means to secure release from illegal detention. Preiser v. Rodriguez, 411 U.S. 475, 484, 93 S.Ct. 1827, 1833, 36 L.Ed.2d 439 (1973); Johnson v. Avery, 393 U.S. 483, 485, 89 S.Ct. 747, 748, 21 L.Ed.2d 718 (1969). Imprisonment of parolees pending revocation is committed to the Parole Commission’s discretion; therefore generally this incarceration must be regarded as legal.
Even action committed to agency discretion, however, may be challenged because it contravenes applicable constitutional, statutory or regulatory provisions. Board of Trade v. Commodity Futures Trading Commission, supra, at 1021 n.6; Coppenbarger v. Federal Aviation Administration, 558 F.2d 836, 838 (7th Cir. 1977). This rule applies to the Parole Commission as it would to any other agency. Tedder v. United States Board of Parole, 527 F.2d 593, 594 n.1; Briney v. United States Parole Commission, 434 F.Supp. 586, 589 (M.D.Fla. 1977).
There are two situations in which a parolee detained during revocation proceedings might properly be granted habeas corpus relief, including bail. The first is when the petition alleges, and the court finds, that the incarceration itself does not comport with constitutional or statutory requirements. An example would be a claim that it would violate equal protection to deny bail to parolees awaiting revocation while making it available to probationers.6 Another example would be a showing that the Commission is not exercising its discretion at all; that its action in denying release is so arbitrary that due process rights are violated.7 A final example would be an allegation that the preliminary hearing was not conducted quickly enough to adhere to the constitutional or statutory requirements.8 If the district court found such claims to be valid, bail might be one form of relief which could be awarded. It would seem, however, that the preferable type of relief would be to order the Commission to correct the constitutional or statutory deficiency in its functioning.9 Release, whether outright or on bail, would rarely be necessary or appropriate.10
The second situation where habeas relief could be awarded is when some other aspect of the revocation procedure is attacked as unconstitutional or contrary to statute or regulation. Here, too, it is conceivable that in very extreme circumstances release might be necessary to fully effectuate the habeas remedy.11
*77Any time a court considers granting bail to a parolee who is detained pending a revocation hearing, it is potentially usurping authority Congress has delegated to the Commission. Before a district court orders bail, a proper respect for the system Congress has established requires that the parolee show that he has requested release from the Parole Commission and has been denied. In addition, bail should not be allowed unless at a minimum the requirements of § 4214(a)(l)(A)(i-iv) are met.
The rule set forth in this opinion will severely restrict the power of the district courts to grant bail to parolees held during revocation proceedings. This standard, however, gives recognition to Congress’ desire to allow the Parole Commission wide discretion in these matters, while at the same time providing the possibility of relief to those parolees who may truly be “illegally” detained.
REVERSED.