Montana state prisoner Leland F. Dock-en brings this federal habeas petition challenging, as here pertinent, the Montana parole board’s refusal to provide him with annual review of his suitability for parole. The district court dismissed this claim as not properly cognizable under the federal habeas statute, 28 U.S.C. § 2254. Because such parole-based claims' — which may, but will not necessarily, affect the duration of a prisoner’s confinement if meritorious- — -are cognizable via habeas, we reverse the district court’s dismissal of Docken’s petition and remand for further proceedings not inconsistent with this opinion.
I. Background
In September 1984, Docken pleaded guilty in a Jefferson County, Montana, court to committing “deliberate homicide” by murdering his father-in-law.
See
MONT. CODE ANN. § 45-5-102. Dock-en was sentenced to 100 years in prison and designated, for purposes of parole eligibility, a “dangerous offender.”
See id.
§ 46-18-404 (repealed 1995). Docken’s plea and sentence were affirmed by the Montana Supreme Court.
See State v. Docken,
In late 2001, the Montana Board of Pardons and Parole (“Board”) denied parole in Docken’s first post-conviction hearing. The Board set the date for his next hearing for September 2006. Soon thereafter, Docken filed a state habeas petition in the Montana Supreme Court, naming Doug Chase, Sheriff of the Missoula County Detention Center, as Respondent.
1
Docken’s
*1026
petition argued, among other claims, that the Board violated his constitutional rights under the Ex Post Facto Clause when it changed the period between his reviews for parole from one year to five. The Montana Supreme Court denied Docken’s petition in a written order, finding none of his state or federal claims persuasive.
See Docken v. Chase,
Docken then filed this habeas petition in the Montana federal district court, raising four principal contentions. The magistrate judge recommended dismissing the first three claims with prejudice, and the fourth, the only claim before us, without prejudice, on the ground that it is not cognizable via habeas but must rather be brought as a civil rights action under 42 U.S.C. § 1983. Citing the Ninth Circuit’s decision in
Neal v. Shimoda,
II. Discussion
We review de novo the district court’s dismissal of a habeas petition under 28 U.S.C. § 2254.
See Hunt v. Pliler,
Traditionally, challenges to prison conditions have been cognizable only via § 1983, while challenges implicating the fact or duration of confinement must be brought through a habeas petition. Looked at in hindsight, the characterization of the problem of parole review frequency is not difficult: For an inmate who will ultimately be paroled at his second parole hearing, whether that hearing is in one year or five indisputably implicates the duration of his confinement. But where the claim is, as here, purely prospective, hindsight is of little use. We cannot know in advance how the parole hearing will turn out. Also, substantively, a timing-of-parole-hearing claim necessarily turns not on the outcome of any hearing but on the asserted legal right to an opportunity to be heard and to have the chance of a shorter confinement. The question this case raises is whether such a prospective challenge is cognizable under § 2254 or § 1983 — or both.
A. Preiser and its Progeny
The landmark precedent for determining whether inmate suits challenging particular aspects of prison conditions may be brought under the federal habeas statute is
Preiser v. Rodriguez,
Preiser
did not stop there. In response to the prisoners’ argument that numerous challenges to prison conditions had been sustained under § 1983, the Court concluded that “a § 1983 action is a proper remedy for a state prisoner who is making a constitutional challenge to the conditions of his prison life, but not to the fact or-length of his custody.”
Id.
at 499,
Dissenting, Justice Brennan expanded on the reserved question: “[E]ven under the
[Preiser
majority’s] approach, there are undoubtedly some instances where a prisoner has the option of proceeding either by petition for habeas corpus or by suit under § 1983.”
Id.
at 504,
Like
Preiser, Heck v. Humphrey,
Also like
Preiser, Heck
addressed only the limited reach of § 1983 with regard to prisoner suits. It did not set out any concomitant limitation on habeas jurisdiction or hold that the habeas and § 1983 causes of action are mutually exclusive.
See also Nelson v. Campbell,
Thus, although Supreme Court case law makes clear that § 1983 is not available where a prisoner’s claim “necessarily” implicates the validity or duration of confinement, it does not set out any mirror-image limitation on habeas jurisdiction. The Court’s central concern, in all of the cases cited above, has been with how far the general remedy provided by § 1983 may go before it intrudes into the more specific realm of habeas, not the other way around. At the same time, though the Court has so suggested, it has never squarely held that there is an area of overlap between state habeas and § 1983 prisoner suits. Instead, it has policed the distinction between the two remedies solely by defining the limits of § 1983, as in Heck, and by defining those classes of claims that must be brought through habeas, as in Preiser. Put simply, when the Supreme Court has concerned itself with the interaction between § 1983 and habeas, it has looked in only one direction.
B. Ninth Circuit Case Law
Our own precedents have more directly addressed the interplay between § 1983 and habeas in the parole context and are somewhat illuminating with regard to the reach of habeas jurisdiction over parole-related prisoner suits. In
Bostic v. Carlson,
Importantly, in speaking of claims only “likely to accelerate” eligibility for parole, Bostic defined a class of suits outside the “core” habeas claims identified in Preiser. Success on the merits in such cases would not “necessarily ” implicate the fact or du *1029 ration of confinement. Instead, such claims have, at best, only a possible relationship to the duration of a prisoner’s confinement, as eligibility for parole is distinct from entitlement to parole.
Following
Bostic,
we have also held that challenges to the procedures used in denying parole are
only
cognizable via habeas.
See Butterfield v. Bail,
Five months after
Butterfield,
this court handed down a decision looking in a somewhat different direction on an issue similar to that raised in
Butterfield. See Neal v. Shimoda,
If Neal and Martinez are successful in their challenge of the SOTP and their labeling as sex offenders, that decision will not undermine the validity of their convictions or continuing confinement at all. The only benefit that a victory in this case would provide Neal and Martinez, besides the possibility of monetary damages, is a ticket to get in the door of the parole board, thus only making them eligible for parole consideration according to the terms of their sentences. If Neal and Martinez win, it will in no way guarantee parole or necessarily shorten their prison sentences by a single day. The parole board will still have the authority to deny the inmates’ requests for parole on the basis of any of the grounds presently available to it in evaluating such a request. A victory in this case would not alter the calculus for the review of parole requests in any way. Because the inmates’ challenge in this case does not necessarily imply the invalidity of their convictions or continuing confinement, it is properly brought under § 1983.
Id. at 824 (footnote omitted). If the district court in this case was correct in reading this passage of Neal for the proposition that § 1983 was the only appropriate remedy (thus foreclosing habeas), then Neal arguably created an intra-circuit split with Bostic, as Bostic held that habeas was appropriate so long as success on the merits would “likely” accelerate eligibility for parole. 3
C. Reconciling the Precedents
One way to reconcile these cases would be to construe Neal as applying only to eligibility for parole vel non, and not to cases — like this one — implicating the timing of parole hearings. Arguably, whether or not an inmate is eligible for parole consideration is less closely related to the duration of his confinement than is the amount of time between the hearings before the parole board for an already-eligible inmate. The timing of parole review is *1030 also more closely tied to “duration” than to “conditions” of confinement. This distinction would not resolve the apparent conflict between Neal and Bostic, however, because Bostic held that the availability of habeas turns on the likelihood that a successful claim will accelerate a prisoner’s eligibility for parole, not his release.
A more sensible reconciliation of the case law, and the one we adopt here, is to regard Neal as holding only that § 1983 was an appropriate remedy in that case, without reaching the issue of whether it was the exclusive remedy. Certainly, nothing in the Neal opinion suggests that § 1983 was available to the prisoners in Neal in lieu of habeas. As in Preiser and Heck, the inmates in Neal were attempting to bring suit under § 1983. The court therefore only reached whether the claim was cognizable under § 1983, without passing on the relationship between § 1983 and habeas. 4
A review of other circuits’ approaches indicates that only the Seventh Circuit has even implicitly suggested that habeas and § 1983 can be mutually exclusive, and that court did so with little analysis and in a different context.
See Moran v. Sondalle,
*1031
As outlined above, the question of the relationship between habeas and § 1983 relief has only explicitly come up before in converse form: whether claims are
not
cognizable under § 1983 because their resolution will necessarily impact the fact and duration of confinement. In the only instance where the Supreme Court addressed whether habeas and § 1983 are necessarily mutually exclusive, the suggestion was that they are not.
See Preiser,
D. Docken’s Claim
Freed from the erroneous constraints of deciding whether Docken’s claim is cognizable via habeas as an either/ or proposition, we must still resolve whether it falls into the area of overlap suggested in Preiser. In light of Bostic, however, this question largely answers itself. It is certainly at least possible that Docken’s suit would impact the duration of his confinement if the Board’s actions in changing the frequency of his parole review violated the Ex Post Facto Clause.
Of course, it is not a certainty that annual review would affect the duration of Docken’s confinement, especially given Docken’s designation as a “dangerous offender.” We are ill-inclined, however, to substitute our substantive analysis of the likely outcome of Docken’s parole hearings for that of the Board. And, in any event, we find nothing in Ninth Circuit or Supreme Court precedent foreclosing habeas in such a case.
Instead, we understand
Bostic’s
use of the term “likely” to identify claims with a sufficient nexus to the length of imprisonment so as to implicate, but not fall squarely within, the “core” challenges identified by the
Preiser
Court. Such a reading follows from
Bostic
itself, which spoke of claims that are “likely to accelerate the prisoner’s
eligibility
for parole,”
Ultimately, though Docken’s claim may not be the kind of “core” challenge the
Preiser
Court had in mind, the potential relationship between his claim and the duration of his confinement is undeniable. In such a case, we are reluctant to unnecessarily constrain our jurisdiction to entertain habeas petitions absent clear indicia of congressional intent to do so.
See, e.g., INS v. St. Cyr,
We therefore hold that when prison inmates seek only equitable relief in challenging aspects of their parole review that, so long as they prevail, could potentially affect the duration of their confinement, such relief is available under the federal habeas statute. Whether such relief is also available under § 1983 depends on the application of Heck’s favorable termination rule in this case, an issue not before us and one that we do not decide.
*1032 Conclusion
Because we hold Docken’s challenge to the timing of his parole review properly cognizable under the federal habeas statute, the district court’s dismissal of Dock-en’s habeas petition is REVERSED, and this case is REMANDED to the district court for further proceedings on the merits of Docken’s claim. 7
IT IS SO ORDERED.
Notes
. Chase appeared in the Montana Supreme Court, represented by the Montana Attorney General. Neither Chase nor the State of Montana, however, have appeared in this federal suit. The district court proceeded under Rule 4 of the Rules Governing Section 2254 Cases in the United States District Courts, which then provided:
If it plainly appears from the face of the petition and any exhibits annexed to it that the petitioner is not entitled to relief in the district court, the judge shall make an order for its summary dismissal and cause the petitioner to be notified. Otherwise the judge shall order the respondent to file an answer or other pleading within the period of time fixed by the court or to take such other action as the judge deems appropriate.
Under Rule 4, because the district court dismissed Docken’s habeas petition sua sponte, Respondent was not required to appear. (Rule 4 has been amended, in a manner not affecting the propriety of the procedure followed by the district court in this case, as of December 1, 2004. See R. GOVERNING § 2254 CASES, 28 U.S.C.A. foil. § 2254, R. 4 (West Supp.2004)). Respondent declined our invitation to submit briefs or present argument concerning this appeal.
. In this regard,
Preiser
was a harbinger of the Court’s subsequent line of cases holding that the existence of specific enforcement provisions in federal statutes forecloses the avail
*1027
ability of a more general remedy under § 1983.
See, e.g., Middlesex County Sewerage Auth. v. Nat’l Sea Clammers Ass'n,
. The district court in this case did not consider the relationship between Neal and Bostic. Rather, it suggested that Neal pertained to eligibility for parole, whereas Butterfield required habeas for challenges to an adverse parole determination based on the procedures used in denying parole. Reading Neal and Butterfield together with Bostic, however, this distinction becomes unworkable.
. We held, in
Ramirez
v.
Galaza,
that "habeas jurisdiction is absent, and a § 1983 action proper, where a successful challenge to a prison condition will not necessarily shorten the prisoner’s sentence."
. One of the five appellants in
Moran
challenged the constitutionality of his parole procedures, and the Seventh Circuit reaffirmed its earlier holdings in
Clark v. Thompson,
. The First, Second, Fifth, Sixth, Eighth, Tenth, and District of Columbia Circuits have all struggled, as we have, with the distinction between the two remedies, particularly in parole-related cases. None have suggested that the avenues of relief must always be mutually exclusive.
See, e.g., Fletcher v. Dist. of Columbia,
No. 02-5228,
The Sixth Circuit concluded in Dotson that Heck’s favorable termination requirement does not cover claims challenging parole procedures, as success on such claims would not necessarily guarantee speedier release. Therefore, the court concluded, challenges to such procedures are cognizable under § 1983. See id. at 472. Though the Supreme Court granted certiorari in Dotson, the questions presented before the Court do not implicate the matter before us. See Questions Presented, Wilkinson v. Dotson, No. 03-287 (U.S. argued Dec. 6, 2004), http://www.supreme- *1031 courtus.gov/qp/ 03-00287qp.pdf. Instead, the Court is asked to decide only whether challenges to parole procedures are cognizable under § 1983. If, as we hold today, the remedies are not always mutually exclusive and are not here mutually exclusive, then the answer to the questions raised in Dotson will not have any bearing on our decision here.
. If Docken has fully exhausted his state remedies (a question not presently before us, and which we do not decide), then the merits of his claim may be largely covered and resolved by the Supreme Court's decision in
Garner v. Jones,
