Opinion by Judge REED; Concurrence by Judge REINHARDT.
REED, District Judge:
Appellant David Means, a member of the Sisseton-Wapatan (Sioux) Tribe of Indians, is currently free on bail pending criminal prosecution in the Tribal Court of the Northern Cheyenne Indian Tribe. After being arrested and freed on bail, but prior to trial, Means sought habeas relief from the district court on jurisdictional grounds. He argued that the Tribal Court does not have criminal jurisdiction over him, as a nonmember Indian, for the crimes with which he is charged. The district court reviewed his petition, but denied relief. The court’s holding was based on a federal statute enacted after all of the acts with which Means is charged were allegedly committed, and which purportedly “recognizes and affirm[s]” the criminal jurisdiction of all tribal courts over all Indians, whether or not members of the same tribe.
Further criminal proceedings in the Tribal Court have been stayed by this court pending disposition of these appeals. Means appeals the district court’s denial of his petition, while the Tribal Court and its Presiding Judge, Glenn Littlebird (collectively, “the Tribal Court” or Appellees), cross-appeal the issue of whether the district court properly entertained Means’ pre-trial habeas petition, or whether “principles of federalism and comity” require that defendants actually be convicted in tribal court before the federal courts intervene.
I. FACTS AND PROCEDURAL HISTORY
On January 10,1997, a complaint was filed in the Northern Cheyenne Tribal Court charging David Means with fifteen counts of aggravated sexual assault, under Section 7-4-7E of the Northern Cheyenne Tribal Code. Each count carries a maximum possible penalty of one year in jail and a $5000.00 fine.1 Ml counts are alleged to have occurred between 1978 and 1988, and the alleged victims are two of Means’ nieces. The comparatively recent filing of the criminal complaint in this case appears to stem from the fact that the victims have only recently “recovered” memories of the abuse, which is alleged to have happened when they were children.
At all times relevant to this case (that is, from prior to 1978 through the present), Means has lived within the Northern Cheyenne Indian Reservation in Montana. However, he is not a member of the Northern Cheyenne Tribe. He is an “Indian,” though, since he is a member of the Sisseton-Wapa-[943]*943tan (Sioux) Tribe.2 Thus Means is a “nonmember Indian” from the Northern Cheyenne Tribal Court’s point of view. As will be discussed in detail below, jurisdiction over crimes committed in “Indian country”3 is divided among tribal, state, and federal courts, depending on the status of the perpetrator and the victim as either non-Indians or Indians-and potentially, at least, as either non-member Indians or tribal members. Thus Means’ status as a non-member Indian is crucial, but again, does not appear disputed.
Means was arrested on the same day that the complaint against him was filed. Bail was set initially at $50,000 cash; reduced to $30,000 cash by the court upon Means’ motion; further reduced to $5000 on appeal; increased back to $30,000 on “full appeal”; and eventually reduced again to $10,000 by stipulation of the parties. Means has been free on bail since January 31, 1997, but he is apparently prohibited from leaving the reservation or the State of Montana, and from contacting children.
Means moved to dismiss the action for lack of jurisdiction on April 9, 1997. The tribal court denied his motion, and Means appealed. The Northern Cheyenne Court of Appeals apparently affirmed the tribal court’s decision “by order ... dated June 20, 1997.” On July 2, 1997, Means filed a complaint in federal district court, which he amended on July 10 to include a claim for habeas corpus relief under 25 U.S.C. § 1303. The district court treated the complaint as a petition for a writ of habeas corpus, which it denied on October 2, 1997. Shortly thereafter, on October 9, 1997, Means timely filed the instant appeal. The Tribal Court and its presiding judge, Glen Littlebird, then filed a notice of cross-appeal on October 23,1997.
II. DISCUSSION
Means’ primary contention is that the Tribal Court does not have jurisdiction to try him for the crimes of which he stands accused. The Tribal Court, on the other hand, claims that its jurisdiction over these crimes is proper, based on the 1990 Amendments to the Indian Civil Rights Act. Since the crimes at issue are alleged to have occurred before 1990, however, the 1990 ICRA amendments will only serve as a basis for jurisdiction if they apply retroactively to conduct completed prior to the amendments’ passage. If the amendments do not apply retroactively, the Tribal Court will not have jurisdiction to try Means for these crimes, and Means’ petition must therefore be granted-sinee, as we discuss below, there is no basis for the Tribal Court’s assertion of jurisdiction over Means other than the 1990 amendments to the ICRA.
A. Retroactivity of the 1990 Amendments to the Indian Civil Rights Act
1. Standard of Review
A district court’s decision on whether a statute may be applied retroactively is a question of law reviewed de novo. Chenault v. United States Postal Serv., 37 F.3d 535, 537 (9th Cir.1994). Likewise, a district court’s denial of a petition for a writ of habeas corpus is reviewed de novo. Selam v. Warm Springs Tribal Correctional Facility, 134 F.3d 948, 951 (9th Cir.1998).
2. Analysis
In determining whether a statute should be applied retroactively, the starting point must of necessity be the statute itself. Here, the statute at issue is the Indian Civil [944]*944Rights Act, or ICRA, codified at 25 U.S.C. §§ 1301-1341. More specifically at issue are the 1990 amendments to 25 U.S.C. § 1301. The current text of this section is set forth below, with language added in 1990 underlined:
§ 1301. Definitions
For purposes of this subehapter, the term—
(1)“Indian tribe” means any tribe, band, or other group of Indians subject to the jurisdiction of the United States and recognized as possessing powers of self-government;
(2)“powers of self-government” means and includes all governmental powers possessed by an Indian tribe, executive, legislative, and judicial, and all offices, bodies, and tribunals by and through which they are executed, including courts of Indian offenses; and means the inherent power of Indian tribes, hereby recognized and affirmed, to exercise criminal jurisdiction over all Indians;
(3)“Indian court” means any Indian tribal court or court of Indian offense; and
(k,)“lndian” means any person who would be subject to the jurisdiction of the United States as an Indian under section 1153 of Title 18 if that person were to commit an offense listed in that section in Indian country to which that section applies.
25 U.S.C. § 1301, as amended by Pub.L. No. 101-511, § 8077 (1990) (emphasis added).
While the new language appears merely to acknowledge the existing state of the law, the 1990 amendments4 were added by Congress in direct response to the Supreme Court case of Duro v. Reina, 495 U.S. 676, 110 S.Ct. 2053, 109 L.Ed.2d 693 (1990). See, e.g., Impact of Supreme Court Ruling in Duro v. Reina: Hearing on S. 962, S. 963 Before the Senate Select Comm. on Indian Affairs, Senate Hearing 158, pts. 1 & 2, 102 Cong., 1st Sess. (1991). Duro had held that an Indian tribe does not have criminal jurisdiction over Indians who are not members of that tribe. Duro, 495 U.S. at 679, 110 S.Ct. 2053. Thus the amendments to the ICRA did constitute a change in the existing law.
(i) The law prior to the 1990 amendments
Immediately prior to the passage of the 1990 amendments, Duro was clearly the governing law. Prior to Duro, however, it was not clear whether Indian tribal courts could exercise criminal jurisdiction over all Indians, or just over the members of their own tribes. On the other hand, it has been clear since the late 1970s both that Indian tribes cannot exercise criminal jurisdiction at all over “non-Indians,” Oliphant v. Suquamish Indian Tribe, 435 U.S. 191, 212, 98 S.Ct. 1011, 55 L.Ed.2d 209 (1978), and that tribes can exercise criminal jurisdiction over their own members. United States v. Wheeler, 435 U.S. 313, 322, 98 S.Ct. 1079, 55 L.Ed.2d 303 (1978). In Duro, the Supreme Court explicitly resolved the remaining issue of “non-member Indians,” which it described as “at the intersection of these two precedents.” Duro, 495 U.S. at 684, 110 S.Ct. 2053.
Duro involved a member of the Torres-Martinez Band of Mission Indians, who had been living on the Salt River Indian Reservation with his girlfriend, a member of the Salt River Pima-Maricopa Indian Community. While within Salt River’s boundaries, Duro allegedly shot and killed a member of the Gila River Indian Tribe. Since both the defendant and the victim were Indians, and since the crime had occurred within Indian country, federal murder charges were brought under the authority of the Major Crimes Act, 18 U.S.C. § 1153. However, when the federal charges were dropped, charges were brought in the Pima-Maricopa Indian Community Court for the “illegal firing of a weapon on the reservation.” Duro, 495 U.S. at 681, 110 S.Ct. 2053.5
[945]*945After the tribal court refused to dismiss the charges on jurisdictional grounds, Duro filed a petition for a writ of habeas corpus in federal district court. The district court granted the writ, but a divided panel of this court reversed. Duro v. Reina, 851 F.2d 1136 (9th Cir.1988), rev’d, 495 U.S. 676, 110 S.Ct. 2053, 109 L.Ed.2d 693 (1990). However, the Supreme Court agreed with the district court that the writ should have been granted. The Court felt that its prior cases, Oliphant and Wheeler, mandated the conclusion that Indian tribes may not exercise criminal jurisdiction over non-member Indians any more than over non-Indians.
Most of Duro is devoted to an examination of the history of tribal sovereignty, the determining factor in both Oliphant and Wheeler. The Court held that tribes do not have “retained tribal sovereignty” over non-members of the tribe, relying heavily on its earlier decisions: In Oliphant, the Court had exhaustively analyzed the history of the relations between the U.S. and various Indian tribes, and concluded that, while the tribes had originally been completely independent and self-governing sovereign political communities, their gradual subjugation to the federal government had limited many of the powers the tribes once had. While an examination of treaties and case law did not necessarily show that the power to try non-Indians had ever been explicitly taken away, it did show that such power was generally assumed (at least by whites) not to exist. In addition, the Court held that express termination by Congress was not the only way tribal powers could be constrained: “Indian tribes are prohibited from exercising both those powers of autonomous states that are expressly terminated by Congress and those powers ‘inconsistent with their status.’” Oliphant, 435 U.S. at 208, 98 S.Ct. 1011 (quoting Oliphant v. Schlie, 544 F.2d 1007, 1009 (9th Cir.1976)). Accordingly, the Court held that the “retained” authority of tribes did not include the ability to exercise criminal jurisdiction over non-Indians, since this would be inconsistent with the tribes’ status as dependent, quasi-sovereign entities.
In Wheeler, on the other hand, the Court was faced with the exercise of tribal criminal jurisdiction over tribal members. Whether the tribes had the power to try their own members was apparently never questioned-the question was where that power originated. The defendant argued that the power had been delegated to the tribes by Congress, so that the tribes, in exercising that power, were acting as arms of the federal government. Consequently, he argued, the fact that he had previously been convicted in tribal court should preclude, under double jeopardy principles, his indictment by a federal grand jury for the same offense. However, the Court held that Indian tribes had not obtained criminal jurisdiction over their own members by affirmative grant of Congress, but rather retained that ability as part of their never-relinquished sovereign power over their own internal affairs. Wheeler, 435 U.S. at 323-24, 98 S.Ct. 1079. Therefore, no double jeopardy problem was presented, since the two prosecutions were by separate sovereigns.
Thus in Duro, the Court faced the question of whether the tribes had also “retained” the inherent authority to exercise criminal jurisdiction over non-member Indians, or whether that power, too, was “inconsistent with their status.” The Court reasoned that its prior holdings made clear that non-member Indians were more like non-Indians in relation to tribes other than their own-that is, both were “external” to the tribe that wished to exert criminal jurisdiction over them. Duro, 495 U.S. at 695-96, 110 S.Ct. 2053. Therefore, it was clear that the “retained inherent authority” of the tribe to exercise power over its internal affairs did not allow the tribe to exert criminal jurisdiction over any nonmembers, whether Indian or not. Id. at 694, 110 S.Ct. 2053. Since it is clear that Means is not a member of the tribe which is at[946]*946tempting to exert criminal jurisdiction over him, then, under Dun, the tribe’s attempt to exercise such jurisdiction must fail.6
(ii) Passage of the 1990 Amendments
Within months of Duro, Congress passed Pub.L. No. 101-511, § 8077 of which amended the ICRA to “legislatively overrule” the Supreme Court’s decision. While the legislative history of this section suggests that Congress did not intend to delegate such authority to the tribes, that is essentially the amendments’ effect. While Congress is always free to amend laws it believes the Supreme Court has misinterpreted, it cannot somehow erase the fact that the Court did interpret the prior law. In other words, once the Supreme Court has ruled that the law is “X,” Congress can come back and say, “no, the law is %’ ” but it cannot say that the law was never “X” or always “Y.” The Court’s decision is the correct statement of what the law always was, even if no one knew it until the Supreme Court so held. See Rivers v. Roadway Empress, Inc., 511 U.S. 298, 313 n. 12, 114 S.Ct. 1510, 128 L.Ed.2d 274 (1994) (“[W]hen this Court construes a statute, it is explaining its understanding of what the statute has meant continuously since the date when it became law.... Thus, it is not accurate to say that the Court’s decision ... ‘changed’ the law that previously prevailed ... when this case was filed. Rather, given the structure of our judicial system, [our] opinion finally decided what [the statute] had always meant....”). Thus regardless of Congress’ intent to declare that tribes always had the inherent authority to try non-member Indians, that simply cannot be what the amendments accomplished. The only way to treat the 1990 ICRA amendments is as an affirmative delegation of jurisdiction, which may or may not apply retroactively, but which did not exist prior to 1990.7
Of course, if Congress could somehow negate the Supreme Court’s ruling in Duro-that is, if Congress had the power to pretend (successfully) that Dun was never decided, and make the final, binding, decision on whether the tribes have always had the retained inherent authority to exercise criminal jurisdiction over non-member Indians-then the 1990 amendments would not constitute an affirmative delegation of jurisdiction. Congress would not really have done anything but acknowledge the already extant state of affairs. Thus jurisdiction would not have been imposed after the fact-on the contrary, the Tribal Court would have had jurisdiction over Means at the time he allegedly committed the crimes. There would have been no need for Congress to impose it retroactively (or prospectively, for that matter). In that case, there would be no need for any further analysis, as there would be no retro-activity question, no ex post facto question, [947]*947no equal protection question, and no due process question. However, as we have discussed, Congress does not have the power to negate a Supreme Court decision. No matter how strongly Congress intended for us to “view the amendments as nullifying Duro and reinstating the criminal jurisdiction of Indian tribes over non-member Indians so that it forms an unbroken line, extending back into history,” Mousseaux v. United States Comm’r of Indian Affairs, 806 F.Supp. 1433, 1443 (D.S.D.1992), we cannot do so. The 1990 amendments must be treated as an affirmative delegation of power, and must consequently be examined to determine if that affirmative delegation should be applied retroactively or not.
(iii) Whether the 1990 amendments should apply retroactively
It is clear that if Means’ acts had occurred after the 1990 amendments were enacted, the amendments would govern. (That is, of course, unless the amendments would be invalid even as prospectively applied, which, as discussed in note 7, supra, might well be the case. Again, however, we do not reach this issue.) Of course, Means’ alleged acts occurred prior to 1990. Thus the amendments will only govern if they are applied retroactively.
A determination of whether a statute should be applied retroactively is generally made according to the criteria set forth in Landgraf v. USI Film Products, 511 U.S. 244, 114 S.Ct. 1483, 128 L.Ed.2d 229 (1994). A major part of the Landgraf analysis turns on whether or not Congress intended for. the statute at issue to apply retroactively. In holding that Congress did intend for the 1990 Amendments to be applied retroactively, the court below relied heavily on Mousseaux, which contains a thorough analysis of the legislative history of the amendments. While there is some room for disagreement as to what Congress’ intent really was, and whether that intent is clearly reflected in the statute, there is no need for us to resolve that question now. Regardless of whether Congress intends a statute to be applied retroactively, we cannot so apply it if its retroactive application would be unconstitutional. And since, as discussed below, the retroactive application of the 1990 Amendments would clearly violate the Ex Post Facto Clause of the Constitution, we must hold that the 1990 Amendments to the ICRA cannot and should not be retroactively applied.
Generally, there is an <ex post facto violation when a law punishes as a crime an act which was not a crime when committed, increases the punishment for a crime after its commission, or deprives a defendant of a defense available at the time the act was performed. Collins v. Youngblood, 497 U.S. 37, 52, 110 S.Ct. 2715, 111 L.Ed.2d 30 (1990). Ex post facto laws are strictly forbidden. U.S. Const, art. I, § 9, cl. 3. Thus if retroactive application of the 1990 amendments would violate the Ex Post Facto Clause, the amendments may not be applied to crimes committed before their enactment.
Appellees argue that, since the 1990 amendments are “merely jurisdictional,” they do not violate the Ex Post Facto Clause. It is true that the Supreme Court has “regularly applied intervening statutes conferring or ousting jurisdiction, whether or not jurisdiction lay when the underlying conduct occurred or when the suit was filed,” since “[application of a new jurisdictional rule usually ‘takes away no substantive right but simply changes the tribunal that is to hear the case.’ ” Landgraf, 511 U.S. at 274, 114 S.Ct. 1483 (quoting Hallowell v. Commons, 239 U.S. 506, 508, 36 S.Ct. 202, 60 L.Ed. 409 (1916)). However, this case appears to be the exception to any presumption there might be in favor of applying “jurisdictional” statutes retroactively, which, to the extent such a presumption exists, seems to have been applied mainly in civil cases, not criminal ones. See, e.g., Landgraf, 511 U.S. at 274, 114 S.Ct. 1483 (citing various eases, all civil, which involved jurisdictional statutes).
Normally, jurisdictional statutes do “simply change[ ] the tribunal that is to hear the case.” Id. Here, however, allowing the Tribal Court to exercise jurisdiction does not prevent the federal courts from exercising jurisdiction as well. There is no question that the federal courts could prosecute [948]*948Means for what he is alleged to have done.8 Since each court could impose its own punishment, granting jurisdiction to the Tribal Court would effectively operate to increase the punishment for acts committed prior to passage of the statute. Prior to the 1990 amendments, Means would only have been subject to federal criminal jurisdiction, and his maximum punishment would have been equal to the maximum federal sentence for his crimes in effect at the time he committed them. If the 1990 amendments are applied retroactively, however, Means would be subject to the maximum federal penalties for his acts plus the maximum penalties the Tribal Court could impose for those same acts, which would appear to be, potentially, an additional fifteen years in jail and $75,000 in fines.9 Thus, regardless of the fact that Means’ acts would have been unlawful under federal law when he allegedly committed them, the increased punishment he would face under the subsequently “affirmed” Tribal Court jurisdiction would seem to present an ex post facto problem.
In addition to increasing the punishment, the retroactive imposition of Tribal Court jurisdiction would also seem to violate the other two strands of the Collins ex post facto test: i.e., punishing as a crime an act which was not a crime when committed, and depriving a defendant of a defense which existed when the act occurred; Collins, 497 U.S. at 52, 110 S.Ct. 2715. It is true that the acts with which Means is charged were crimes under the Tribal Code at the time they were allegedly committed. However, at the time, the Tribal Court could not have tried or punished Means for those crimes, since it lacked jurisdiction over him. Since what constitutes “a crime” is essentially what the sovereign defines as “a crime,” if the sovereign has no power over an individual then it essentially lacks the ability to define any of that individual’s conduct as a crime. Thus while the conduct in question here might have been a crime, it was not a crime as to Means at the time it was allegedly committed. Imposing jurisdiction retroactively therefore makes it a crime as to Means after the fact-exactly what is forbidden by the Ex Post Facto Clause.
To look at it yet another way, the retroactive application of the 1990 amendments would also deprive Means of a defense that was available at the time of his alleged crimes. The fact that the Tribal Court lacked criminal jurisdiction over Means would have been a complete defense to his prosecution by the Tribe. The fact that the 1990 amendments if applied retroactively would deprive him of this defense after the fact is yet another reason why the amendments would pose a serious ex post facto problem if applied retroactively.
Since applying the 1990 amendments retroactively would produce an ex post facto problem, then we will not do so. Whether or not we assume that Congress intended to pass this unconstitutional ex post facto law, the result is the same-the 1990 amendments cannot be applied retroactively. Of course, as we have already mentioned, there might well be problems with the 1990 amendments even as prospectively applied, but such problems must await another day for resolution.
Therefore, given the ex post facto problems that would arise were we to apply the 1990 amendments retroactively, we hold that the 1990 amendments to the ICRÁ should not apply retroactively to grant criminal jurisdiction to tribal courts over acts committed by non-member Indians prior to 1990. Consequently, the Northern Cheyenne Tribal Court lacks jurisdiction to try Means for the pre-1990 crimes with which he is charged, and the district court should thus have grant[949]*949ed Means’ petition for a writ of habeas corpus.
For the foregoing reasons, we reverse the district court’s decision to apply the 1990 amendments retroactively, and remand to that court so Means’ petition may be granted.
B. The District Court’s Exercise of Jurisdiction over Means’ Pre-Trial Habeas Petition
In addition to arguing that the district court was correct in denying Means’ petition, the Appellees contend that the court should never have entertained the petition in the first place. Originally, Appellees contended that the district court should not have considered Means’ habeas petition because he was not “detained” as required by 25 U.S.C. § 1808. However, they have now conceded that this is not the case, and that Means is sufficiently “detained” by the fact that, as conditions of his release on bail, he is forbidden from leaving the reservation and from contacting children.
Currently, Appellees’ principal contention is that the district court should not have entertained Means’ petition because he has not yet been tried. They acknowledge that pre-trial habeas petitions may be reviewed, but only if “special circumstances” are shown. Carden v. Montana, 626 F.2d 82, 83 (9th Cir.1980). They claim that the district court should have required Means to show that such special circumstances existed before allowing him to proceed with his petition.
While this particular issue does not appear to have been raised before in the context of the habeas remedy peculiar to the Indian Civil Rights Act, 25 U.S.C. § 1303, the general reluctance to interfere with on-going state criminal trials can generally be said to extend to tribal courts. However, this is usually examined in the context of the requirement that tribal remedies be exhausted before the federal courts will get involved. The “principles of federalism and comity” that preclude most pre-trial grants of habeas relief in state cases are reflected here in the exhaustion requirement. See Iowa Mutual Ins. Co. v. LaPlante, 480 U.S. 9, 15 & 16 n. 8, 107 S.Ct. 971, 94 L.Ed.2d 10 (1987) (holding, in the context of a civil case, that “considerations of comity direct that tribal remedies be exhausted before the question is addressed by the District Court” and that “[e]xhaustion is required as a matter of comity, not as a jurisdictional prerequisite”). Duro itself was a pre-trial habeas case, and even with all the discussion over whether the writ should have been granted, it does not appear to have been disputed that the district court’s review of the petition was proper.
Our cases make clear that pre-trial relief was appropriate in these narrow circumstances. “[W]hen a tribal court attempts to exercise criminal jurisdiction over a person not a member of a tribe, no requirement of exhaustion need be enforced.” Selam v. Warm Springs Tribal Correctional Facility, 134 F.3d 948, 954 (9th Cir.1998) (quoting Wetsit v. Stafne, 44 F.3d 823, 826 (9th Cir.1995)). Further, to the extent that any exhaustion was required in this case, it would appear that Means has in fact met the requirement. He presented his jurisdictional argument first to the Tribal Court, and then to the Northern Cheyenne Court of Appeals. Both courts denied his claim before he filed his petition with the district court. Since the purpose of the exhaustion requirement is to promote “tribal self-government and self-determination” by allowing tribal courts to “have the first opportunity to evaluate the factual and legal bases for the challenge to [their] jurisdiction,” the requirement would appear to have been satisfied here. Iowa Mutual 480 U.S. at 15-16, 107 S.Ct. 971. The Northern Cheyenne courts appeal’ to have had a full opportunity to examine the jurisdictional question. Therefore, we affirm the district court’s exercise of jurisdiction over Means’ habeas petition.
C. Conclusion
While we affirm the district court’s exercise of jurisdiction over Means’ pre-trial ha-beas petition, we reverse the denial of that petition, and remand so that the petition may be granted.
[950]*950AFFIRMED in part, REVERSED in part, and REMANDED.