OPINION

RABINOWITZ, Justice.

I. INTRODUCTION.

On March 12, 1980, Robert Creekpaum allegedly sexually assaulted a nine year old girl. On May 17, 1985, a grand jury in Juneau returned an indictment against Creekpaum for "a class A felony . . . in violation of [former] AS 11.41.410(a)." Creekpaum filed a motion to dismiss the case on June 20, 1985, on the grounds that the applicable statute of limitations had run and the indictment was untimely.

At the time of Creekpaum's alleged offense in March 1980, the applicable statute of limitations, AS 12.10.010, specified a five year period in which the indictment was to be found, or the information or complaint instituted. In 1983, before the five year period of limitations had run on Creekpaum's alleged offense, the legislature enlarged the period for bringing charges of sexual abuse of a minor. Alaska Statute 12.10.020(c) provides:

Even if the general time limitation has expired, a prosecution under AS 11.41.410- 11.41.460 . . . for an offense committed against a person under the age of 16 may be commenced within one year after the crime is reported to a peace officer or the person reaches the age of 16, whichever occurs first. This subsection does not extend the period of limitation by more than 5 years.

Creekpaum was indicted five years and two months after the alleged offense. He argues that his indictment was untimely under AS 12.10.010, and that AS 12.10.020(c), the extended statute of limitations, would amount to an unconstitutional ex post facto law if applied to his case. The state concedes that if the statute of limitations in effect at the time of the incident governs the case, the indictment must be dismissed. It argues, however, that the later extension of the limitations period in AS 12.10.020(c) governs, and that Creekpaum was timely indicted.

The superior court agreed with Creekpaum's argument that, as applied to him, the changed statute of limitations was an unconstitutional ex post facto law. The court of appeals upheld the superior court's ruling by a 2-1 vote with Judge Singleton dissenting. State v. Creekpaum, 732 P.2d 557 (Alaska App. 1987). We reverse the court of appeals and hold that extension of a criminal statute of limitations before the original period of limitation has run is not an unconstitutional ex post facto law under the constitutions of either Alaska or the United States.

II. DISCUSSION.

Our decision is based primarily upon our reading of Weaver v. Graham, 450 U.S. 24, 101 S.Ct. 960, 67 L.Ed.2d 17 (1981). Both the superior court and the court of appeals found Weaver to be dispositive of Creekpaum's case, and ruled that the extended statute of limitations was unconstitutional as applied to Creekpaum.

The petitioner in Weaver challenged on ex post facto grounds a change in Florida's statutory formula for calculating "good time" reductions in prisoners' sentences. The change made it more difficult to accrue good time reductions, thereby increasing the "quantum of punishment" suffered by each inmate. The Supreme Court held that the statute violated the ex post facto prohibition because it "makes more onerous the punishment for crimes committed before its enactment." 450 U.S. at 36, 101 S.Ct. at 968, 67 L.Ed.2d at 27.

Creekpaum argues that Weaver introduced a new analytic approach to ex post facto cases, one that discarded the traditional "vested rights" approach. He argues that the premise behind the vested rights approach was "that a criminal defendant's right to rely upon the statute of limitations as it existed when the alleged crime was committed applies only when that right has vested." He further argues that in place of the vested rights approach, the Court focused only on two criteria: whether the law was retrospective and whether it disadvantaged the offender affected by it.

In Weaver the Court did note that "a law need not impair a `vested right' to violate the ex post facto prohibition." Id. at 29, 101 S.Ct. at 964, 67 L.Ed.2d at 23. The Court clarified that statement in a footnote:

When a court engaged in ex post facto analysis, which is concerned solely with whether a statute assigns more disadvantageous criminal or penal consequences to an act than did the law in place when the act occurred, it is irrelevant whether the statutory change touches any vested rights.

Id., n. 13. The Court focused on the critical considerations of the ex post facto doctrine:

The presence or absence of an affirmative, enforceable right is not relevant, however, to the ex post facto prohibition, which forbids the imposition of punishment more severe than the punishment assigned by law when the act to be punished occurred. Critical to relief under the Ex Post Facto Clause is not an individual's right to less punishment, but the lack of fair notice and governmental restraint when the legislature increases punishment beyond what was prescribed when the crime was consummated. Thus, even if a statute merely alters penal provisions accorded by the grace of the legislature, it violates the Clause if it is both retrospective and more onerous than the law in effect on the date of the offense.

Id. at 30-31, 101 S.Ct. at 965, 67 L.Ed.2d at 24.

The Court then considered the Florida law in light of the two considerations: whether it was retrospective and whether it was more onerous than the law in effect on the date of Weaver's offense. With regard to the first criterion, the Court found:

For prisoners who committed crimes before its enactment, § 944.275(1) substantially alters the consequences attached to a crime already completed, and therefore changes "the quantum of punishment." Therefore, it is a retrospective law which can be constitutionally applied to petitioner only if it is not to his detriment.

Id. at 33, 101 S.Ct. at 966, 67 L.Ed.2d at 25 (citing Dobbert v. Florida, 432 U.S. 282, 293-94, 97 S.Ct. 2290, 2298, 53 L.Ed.2d 344 (1977)).

The Court next determined that the new law operated to Weaver's detriment:

Under this inquiry, we conclude § 944.275(1) is disadvantageous to petitioner and other similarly situated prisoners. On its face, the statute reduces the number of monthly gain-time credits available to an inmate who abides by prison rules and adequately performs his assigned tasks. By definition, this reduction in gain-time accumulation lengthens the period that someone in petitioner's position must spend in prison.

Id. 450 U.S. at 33, 101 S.Ct. at 966, 67 L.Ed.2d at 26. The Court accordingly held that the new statute violated the ex post facto prohibition of the Constitution.

In Miller v. Florida, 482 U.S. ___, 107 S.Ct. 2446, 96 L.Ed.2d 351 (1987), the Court relied upon its analysis in Weaver to conclude that a change in Florida's sentencing guidelines between the time of Miller's offense and his sentencing violated the ex post facto clause.

As was stated in Weaver, to fall within the ex post facto prohibition, two critical elements must be present: first, the law "must be retrospective, that is, it must apply to events occurring before its enactment"; and second, "it must disadvantage the offender affected by it."

At ___, 107 S.Ct. at 2451, 96 L.Ed.2d at 360 (quoting Weaver, 450 U.S. at 29, 101 S.Ct. at 964, 67 L.Ed.2d at 23).

The Court also relied on Dobbert v. Florida, 432 U.S. 282, 97 S.Ct. 2290, 53 L.Ed.2d 344 (1977), to emphasize "that no ex post facto violation occurs if a change does not alter `substantial personal rights,' but merely changes `modes of procedure which do not affect matters of substance.'" Miller, 482 U.S. at ___, 107 S.Ct. at 2451, 96 L.Ed.2d at 360 (quoting Dobbert, 432 U.S. at 293, 97 S.Ct. at 2298, 53 L.Ed.2d at 356). As in Weaver, the Court in Dobbert focused on the quantum of punishment which the petitioner would suffer under the new law:

The new statute simply altered the methods employed in determining whether the death penalty was to be imposed; there was no change in the quantum of punishment attached to the crime.

432 U.S. at 293-94, 97 S.Ct. at 2298, 53 L.Ed.2d at 356.

The Court in Miller also relied heavily on traditional ex post facto considerations as applied in Dobbert:

[T]his is not a case where we can conclude, as we did in Dobbert, that "[t]he crime for which the present defendant was indicted, the punishment prescribed therefore, and the quantity or the degree of proof necessary to establish his guilt, all remained unaffected by the subsequent statute."

482 U.S. at ___, 107 S.Ct. at 2454, 96 L.Ed.2d at 363 (quoting Dobbert, 432 U.S. at 294, 97 S.Ct. at 2298, 53 L.Ed.2d at 357). Rather, "[t]he law at issue in this case, like the law in Waver, [sic] `makes more onerous the punishment for crimes committed before its enactment.'" Miller, 482 U.S. at ___, 107 S.Ct. at 2454, 96 L.Ed.2d at 363 (quoting Weaver, 450 U.S. at 36, 101 S.Ct. at 968, 67 L.Ed.2d at 27).

Viewed in light of Miller, Weaver is not a major departure from prior ex post facto doctrine. It does not "call . . . into serious and substantial question" all the prior cases on which the state relies, as Creekpaum argues. The interpretation of Weaver urged by the state and by Judge Singleton's dissent conforms to the interpretation given to it by the Supreme Court. That is, the holding in Weaver falls "within the core of the prohibition announced in Calder [ v. Bull, 3 U.S. (3 Dall.) 386, 1 L.Ed. 648 (1798)]," Creekpaum, 732 P.2d at 570 n. 3 (Singleton, J., dissenting), because it focused on the change in the quantum of punishment that Weaver suffered as a result of the new law.

This analysis leads us to apply the two step test prescribed in Weaver and Miller. First, the law is explicitly retroactive. Second, Creekpaum argues that the new law is more onerous because he remains liable for prosecution from which he would have been immune under the old law. This argument is not persuasive in light of the specifically enumerated criteria employed in traditional ex post facto analysis.

For example, the Supreme Court's description of the effect of the statute in Dobbert, quoted above, applies equally to the new statute of limitations in the instant case: "The crime for which the present defendant was indicted, the punishment prescribed therefor, and the quantity or the degree of proof necessary to establish his guilt, all remained unaffected by the subsequent statute." 432 U.S. at 294, 97 S.Ct. at 2298, 53 L.Ed.2d at 357 (quoting Hopt v. Utah, 110 U.S. 574, 589-90, 4 S.Ct. 202, 209-10, 28 L.Ed. 262, 268 (1884)), quoted in Miller, 482 U.S. at ___, 107 S.Ct. at 2454, 96 L.Ed.2d at 363. Judge Singleton's dissent similarly specifies settled criteria which a law must meet before it will be held unconstitutional under the ex post facto clause.

[A] statute violates the ex post facto prohibition if, and only if: (1) it makes conduct criminal which would have been innocent when undertaken; (2) it aggravates a crime or makes it greater than it was when committed; (3) it permits imposition of a different and more severe punishment than was permissible when the crime was committed; and, (4) it changes the legal rules of evidence to permit less or different testimony to convict the offender than was required when the crime was committed. Calder v. Bull, 3 U.S. (3 Dall.) 386, 390, 1 L.Ed. 648 (1798).

Creekpaum, 732 P.2d at 569 (Singleton, J., dissenting). Under either set of considerations, the changed statute of limitations does not violate the ex post facto clause. Furthermore, we see no reason to construe our parallel ex post facto prohibition — article I, section 15 — differently from the federal provision.

Because the impact of Weaver is far more limited than Creekpaum and the courts below asserted, it does not nullify the precedent upon which the state relies in urging us to apply the extended statute of limitations to Creekpaum's case. We find one of those precedents, Clements v. United States, 266 F.2d 397 (9th Cir.), cert. denied, 359 U.S. 985, 79 S.Ct. 943, 3 L.Ed.2d 934 (1959), particularly persuasive in this case.

At the time of Clements' offense (transporting a woman in interstate commerce for the purposes of prostitution), the statute of limitations was three years. Before the three years had expired, Congress amended the statute to allow prosecution to be commenced within five years of the offense. The Ninth Circuit, relying upon United States v. Powers, 307 U.S. 214, 59 S.Ct. 805, 83 L.Ed. 1245 (1939), rejected Clements' ex post facto challenge to the law.

The amendment was not an ex post facto law. It did not render a previously innocent act criminal. This statute did not aggravate or increase the punishment for the crimes here involved. The enactment did not alter the rules of evidence. An innocent act was not thereby penalized while assuming to regulate civil rights and remedies. Nor was the accused deprived thereby of some protection or defense previously available.

266 F.2d at 399.

The Seventh Circuit, relying on Clements, also explicitly held that the extension of a statute of limitations was "a `merely procedural' change" which did "not increase the punishment nor change the ingredients of the offense or the ultimate facts necessary to establish guilt." United States ex rel. Massarella v. Elrod, 682 F.2d 688, 689 (7th Cir. 1982) (quoting Weaver, 450 U.S. at 29 n. 12, 101 S.Ct. at 964 n. 12, 67 L.Ed.2d at 23 n. 12, and Hopt, 110 U.S. at 590, 4 S.Ct. at 210, 28 L.Ed. at 269), cert. denied, 460 U.S. 1037, 103 S.Ct. 1426, 75 L.Ed.2d 787 (1983). The court upheld the extension in the face of an ex post facto challenge.

We are persuaded by these precedents that the extension of the statute of limitations for the offense with which Creekpaum has been charged, before the original period of limitations had expired, does not violate the federal or the Alaska Constitution. We therefore REVERSE the decisions of the court of appeals.