dissenting.
My brethren have decided to remand the case for a factual inquiry into the practices followed by the Parole Board under the old statute. I disagree with this disposition, mainly because I do not think that the practices of courts or executive agencies are material in deciding whether a law is a forbidden ex post facto law. The prohibition in Article I, section 9 of the Constitution against ex post facto laws is directed at Congress rather than the other branches of the federal government. If judges decide to get tougher on crime, or prosecutors drive harder plea bargains, or parole boards take a more jaundiced view of applications for parole, there is no violation of the prohibition even though a criminal’s punishment may end up being longer or harsher than he could reasonably have expected when he committed the crime. As many cases hold, there is no violation even if the Parole Commission makes its parole guidelines more severe. See, e.g., Zeid-man v. United States Parole Comm’n, 593 F.2d 806, 808 (7th Cir.1979); Dufresne v. Baer, 744 F.2d 1543, 1549-50 (11th Cir. 1984). Formally, the prohibition against ex post facto laws is limited to statutory changes which increase the severity of punishment, as by lengthening the maximum term of imprisonment or eliminating credit for good behavior in prison or abolishing or restricting parole. By a modest extension the prohibition can be made to embrace regulations (products of an exercise of delegated legislative power) that have any of these effects. See, e.g., United States ex rel. Graham v. United States Parole Comm’n, 629 F.2d 1040, 1043 (5th Cir. *12411980). But there are no regulations here. Thus we have only to compare the 1969 federal parole statute with the 1976 revision.
The 1969 statute provides, “if it appears to the Board of Parole ... that there is a reasonable probability that such prisoner will live and remain at liberty without violating the laws, and if in the opinion of the Board such release is not incompatible with the welfare of society, the Board may in its discretion authorize the release of such prisoner on parole.” 18 U.S.C. § 4203(a) (1970 ed.) (emphasis added). The 1976 statute, so far as relevant here, provides that the prisoner “shall be released” if the Parole Commission determines that his release “would not depreciate the seriousness of his offense or promote disrespect for the law” and “would not jeopardize the public welfare.” 18 U.S.C. § 4206(a) (emphasis added). I do not think that anyone just reading these two statutes would think the second more restrictive than the first. The first emphatically reserves to the Parole Board discretion not to release the prisoner even if he meets the statutory conditions. The second makes parole mandatory, provided the statutory conditions are met. Solomon v. Elsea, 676 F.2d 282, 285 (7th Cir.1982) (per curiam). The conditions are slightly different; but if anything the second statute is more liberal, in entitling the prisoner to parole if certain conditions are met rather than putting him entirely at the mercy of the parole authorities. Thus Prater’s claim fails at the threshold; he has not shown that the new statute is harsher than the old. See Dobbert v. Florida, 432 U.S. 282, 294, 97 S.Ct. 2290, 2298, 53 L.Ed.2d 344 (1977); Crowell v. United States Parole Comm’n, 724 F.2d 1406, 1408-09 (3d Cir.1984).
Whether the new statute is harsher than the Parole Board’s practices under the old statute is an issue both difficult to resolve by the methods of litigation and remote from the central purpose of prohibiting ex post facto laws, which is to protect expectations. No person contemplating criminal activity should be encouraged to rely on the current practices of judges, or prosecutors, or prison officials, or parole boards; that is not the sort of reliance that the prohibition against ex post facto laws ought to protect or does protect. Besides the parole-guidelines cases cited earlier, see Holguin v. Raines, 695 F.2d 372, 374 (9th Cir.1982) (judicial interpretation of statute), and Glynn v. Auger, 678 F.2d 760, 761 (8th Cir.1982) (per curiam) (double-celling of inmates) — illustrative cases where the prohibition was held inapplicable to nonlegisla-tive actions that in fact increased the severity of punishment for a crime and did so retroactively. Of course there is the danger of a legislature’s using delegation to executive, administrative, or judicial officers to get around the prohibition against ex post facto laws, and the closely related danger of encouraging legislatures to enact vague statutes. But these are not dangers in this case; there is no suggestion that either act delegates excessively, or is too vague. Hence it should be enough that under the 1969 act the Parole Board could have refused to parole someone because of the enormity of his crime, even if he was completely rehabilitated, and as harmless as a white mouse; it is unnecessary to add that, on occasion, it did so. See Garcia v. United States Board of Parole, 557 F.2d 100, 105 (7th Cir.1977), where we upheld such a refusal as consistent with the 1969 act. The fact that the Parole Board may not often have exercised its power to deny parole because of the enormity of the crime would not give a prisoner a right to be paroled regardless of that enormity. In the nature of things, such power is unlikely to be exercised often; crimes as outrageous as Prater’s are rare.
Heirens v. Mizell, 729 F.2d 449, 457-65 (7th Cir.1984), does not compel my brethren’s result. It is true that the court there inquired at length into the actual practice under the old statute, and found it consist-' ent with the new. See id. at 459-63. That cooked the petitioner’s goose; but to draw the negative inference that if the practice had been different the state would have lost is unwarranted, especially since Heir-ens cites with approval the district court’s *1242decision in the,present case — the decision my brethren reverse today — noting that it “denied a similar ex post facto claim against the federal Parole Commission on grounds in accord with the present case.” 729 F.2d at 464 n. 17. But if I am wrong and we must consider the Parole Board’s actual behavior under the 1969 statute, the majority opinion has provided the materials for a conclusion that parole would indeed have been denied when the offense was so egregious that paroling the offender would outrage the community: in its citation to the discussion in Kastenmeier & Eglit, Parole Release Decision-making: Rehabilitation, Expertise, and the Demise of Mythology, 22 Am.U.L.Rev. 477, 508, 516 (1973), of the Parole Board’s practices. And as I said, we upheld such a denial in the Garcia case. See 557 F.2d at 105-06. Thus the majority’s result seems unacceptable even if its premises are correct— which I earnestly suggest they are not.
Although my brethren only remand the .case, let there be no misapprehension about the significance of this decision. Any federal prisoner who committed his crime before the enactment of the 1976 parole statute has a potential ex post facto claim under the decision today. The decision will also leave the Parole Commission in grave doubt as to whether it can apply the current statute to prisoners — who must be legion — who committed their crimes before 1976. The implications for state prisoners in this circuit are equally far-reaching, given the parallel prohibition in Article I, section 10 of the Constitution against ex post facto legislation by the states.