announced the Judgment of the Court and delivered an Opinion with respect to Part III, in which Justice VOLLACK joined. Justice ERICKSON filed a specially concurring opinion as to Part III.
Justice MULLARKEY filed an opinion concurring in the judgment as to Part III. Justice LOHR filed a dissent as to Part III, which Justice QUINN joined in its entirety and Justice KIRSHBAUM joined in Parts I, II, and III thereof.The People of the State of Colorado (People) appeal two rulings of the Adams County District Court denying their motions to seek the death penalty against the defendant, Allen Thomas, Jr., who is charged with first degree murder under section 18-3-102(l)(a), 8B C.R.S. (1986), a class one felony offense which occurred in February, 1991.
In July, 1991, in People v. Young, 814 P.2d 834 (Colo.1991), we held that the death penalty sentencing statute was unconstitutional (§ 16-11-103, 8A C.R.S. (1988 Supp.) (“1988 statute”)). Following Young, the trial court ruled that the People could not, pursuant to the revival doctrine, seek the death penalty under the sentencing statute that preceded the unconstitutional provision, section 16-11-103, 8A C.R.S. (1986) (“pre-1988 statute”).1 In response to Young, the legislature enacted two bills. The first rendered possible the imposition of the death penalty for class one felony offenses committed on or after September 20, 1991. House Bill 91S2-1001, act approved Sept. 20, 1991, ch. 4, sec. 1, § 16-11-103, 1991 Colo.2d Ex.Sess.Laws 8. The second enacted two statutes with the express intent of making the death penalty available as a sentence for persons convicted of class one felony offenses which occurred on or after July 1, 1988 and prior to September 20, 1991. House Bill 91S2-1038, act approved Oct. 11, 1991, ch. 6, sec. 1, §§ 16-11-801 and -802, 1991 Colo.2d Ex. Sess.Laws 16. The district court ruled that the second bill could not be applied to Thomas without violating the constitutional proscription against ex post facto laws.
The People appeal both trial court rulings.2 We agree that the doctrine of reviv*185al cannot operate to resurrect the pre-1988 statute and the People cannot seek the death penalty under this doctrine. Nonetheless, because sections 16-11-801 and - 802, the statutes enacted to cover the period from July 1,1988 to September 19,1991, do not violate the ex post facto clauses of either the United States or the Colorado Constitutions, the People may seek the death penalty under these statutory provisions. Accordingly, we affirm the trial court’s first order and reverse its second order.
I
Colorado has had a death penalty statute in effect since 1861, with the exception of a brief interruption between 1897 and 1901. People v. Davis, 794 P.2d 159, 171 n. 3 (Colo.1990), cert. denied, — U.S. —, 111 S.Ct. 662, 112 L.Ed.2d 656 (1991) (citing Colorado Legislative Council, An Analysis of 1966 Ballot Proposals, Research Publication No. 110, at 32). The predecessor to the current death penalty sentencing statute initially appeared in 1972 when the legislature adopted the Colorado Code of Criminal Procedure. Ch. 44, sec. 1, § 39-11-103, 1972 Colo.Sess.Laws 190, 240-41. Since that time, the statute has been subject to numerous legislative amendments. Because the order of certain events plays an important role in our decision, a chronological review of recent death penalty statutory amendments related to the events in this case provides our starting point.
Prior to 1988, Colorado’s death penalty statute required a jury to follow a four step sentencing procedure in determining whether to impose a sentence of life imprisonment or death penalty. See § 16 — 11— 103, 8A C.R.S. (1986) (“pre-1988 statute”). In People v. Tenneson, 788 P.2d 786, 789 (Colo.1990), we outlined these four steps:
First, the jury must determine if at least one of the statutory aggravating factors exists. §§ 16-ll-103(2)(a)(I), -(6). If the jury does not unanimously agree that the prosecution has proven the existence of at least one statutory aggravator beyond a reasonable doubt, the defendant must be sentenced to life imprisonment. §§ 16-ll-103(l)(d), -(2)(b)(I), -(2)(c). Second, if the jury has found that at least one statutory aggravating factor has been proven, the jury must then consider whether any mitigating factors exist. §§ 16-ll-103(2)(a)(II), -(5).... Third, the jury must determine whether “sufficient mitigating factors exist which outweigh any aggravating factor or factors found to exist.” § 16-ll-103(2)(a)(II). Fourth, and finally, if the jury finds that any mitigating factors do not outweigh the proven statutory aggravating factors, it must decide whether the defendant should be sentenced to death or to life imprisonment. § 16-11-103(2)(a)(III).
The fourth step, therefore, required the jury to make an independent decision whether to impose a sentence of life imprisonment or death where mitigating factors did not outweigh aggravating factors.
In 1988, the death penalty statute was amended (“1988 statute”) by Senate Bill 78 to eliminate this fourth step by consolidating the third and fourth steps of the pre-1988 statute. See S.B. 78, ch. 114, sec. 1-3, § 16-11-103, 1988 Colo.Sess.Laws 673, 674-75 (codified at § 16-11-103, 8A C.R.S. (1988 Supp.)). In section 3, Senate Bill 78 specifically repealed section 16 — 11— 103(2)(a)(III), 8A C.R.S. (1986), the source of the former fourth step. See id., sec. 3 at 675. The 1988 statute required a jury to return a sentence of death if there were insufficient mitigating factors to outweigh aggravating factors. See id., sec. 2. After •the amendment, the death penalty statute read in pertinent part:
In the event that the jury finds that at least one statutory aggravating factor has been proved beyond a reasonable doubt, and that there are insufficient statutory mitigating factors or other mitigating circumstances to outweigh any statutory aggravating factor or factors that were proved and any other aggravating circumstances that were proved, the jury shall return a sentence of death.
*186§ 16 — 11—103(2)(b)(III), 8A C.R.S. (1988 Supp.).
Following enactment of the 1988 statute, the death penalty itself survived a constitutional challenge grounded in the state constitutional due process and equal protection provisions and the prohibition against cruel and unusual punishment. People v. Davis, 794 P.2d 159, 170-75 (Colo.1990), cert, denied, — U.S. -, 111 S.Ct. 662, 112 L.Ed.2d 656 (1991) (finding the pre-1988 sentencing statute, applicable at the time of the offenses committed by the defendant, constitutional). In 1990, we also decided People v. Tenneson, 788 P.2d 786 (Colo.1990), in which the prosecution challenged jury instructions given under the then applicable pre-1988 statute.3 In Ten-neson, in interpreting the third and fourth steps of the pre-1988 statute, we held that “before a defendant may be sentenced to death the jury must be convinced beyond a reasonable doubt that any mitigating factors do not outweigh the proven statutory aggravating factors.” Id. at 790. Subsequently, in People v. O’Neill, 803 P.2d 164, 178-79 (Colo.1990), we upheld defendant’s argument that the jury was not under any burden of persuasion in its fourth step of deliberations in violation of Tenneson. In a footnote, we noted that the fourth step had been eliminated by the 1988 amendment but that the pre-1988 statute was in effect at the time of the offense in O’Neill. We found that the jury had not, by virtue of the instructions given, been placed under any burden of persuasion in its fourth step of deliberations and stated that “Tenneson clearly mandates that the jury find that death is the appropriate penalty beyond a reasonable doubt.” O’Neill, 803 P.2d at 178.
After these cases were decided, an information was filed charging Thomas with several felony offenses that occurred in February 1991, including first degree murder.4 At a hearing in May 1991, the People informed the defendant and the court of their intention to seek the death penalty.5
On July 9, 1991, our decision in People v. Young, 814 P.2d 834 (Colo.1991), was announced. In Young, we invalidated the 1988 statute on the grounds that the elimination of the fourth step “violates fundamental requirements of certainty and reliability under the cruel and unusual punishment and due process clauses of the Colorado Constitution.” Id. at 846.
Shortly thereafter, citing Young, the defendant requested an order from the trial court prohibiting the People from seeking the death penalty under the 1988 statute. The People opposed the motion, asserting that the determination that the 1988 statute was unconstitutional operated to “revive” the pre-1988 statute or, alternatively, should the General Assembly adopt a new procedural death penalty law before Thomas’ trial, the People should be allowed to seek the death penalty under the newly enacted statute.
On July 29, 1991, Thomas entered a plea of not guilty to the charge of first degree *187murder.6 In August, after a hearing on the availability of the death penalty and the effect of the Young decision, the court rejected the “revival” argument and, without commenting on the assertion that a subsequently enacted death penalty could be applied, struck the death penalty from consideration.
In early September, the People filed an original proceeding in this court requesting review of the order striking the death penalty, again arguing that the pre-1988 statute was revived after the decision in Young and that, if a new procedural death penalty statute was enacted, the new statute should be given retroactive effect. We denied that petition without prejudice.
In response to our decision in Young, section 16-11-103 was- repealed and reenacted with amendments by the General Assembly. House Bill 91S2-1001 amended section 16-ll-103(2)(b) to again require the fourth step, an independent determination by the jury whether to impose a sentence of life imprisonment or death when mitigating factors do not outweigh aggravating factors. Act approved Sept. 20, 1991, ch. 4, sec. 1, § 16-11 — 103(2)(b)(II), 1991 Colo.2d Ex.Sess.Laws 8 (codified as § 16-11-103(2)(b)(II), but not yet appearing in the published Colorado Revised Statutes) (“House Bill 91S2-1001”).
As a result of the enactment of House Bill 91S2-1001, the People filed a second motion with the trial court seeking an order allowing them to pursue the death penalty, asserting that the new law governed the trial in this case. Following a hearing, the court took the matter under advisement after being informed that another bill had passed the House and the Senate (but had not yet been signed into law) relating to the period between the enactment of the unconstitutional 1988 statute and the enactment of House Bill 91S2-1001.
In October, clearly stating its intent that “there be no hiatus in the imposition of the death penalty as a sentence for the commission of a class 1 felony in the State of Colorado as a result of the holding of the Colorado Supreme Court in People v. Young," 814 P.2d 834, the legislature passed House Bill 91S2-1038, which enacted two new statutes. Act approved Oct. 11, 1991, ch. 6, sec. 1, §§ 16-11-801 and - 802,1991 Colo.2d Ex.Sess.Laws 16 (codified as §§ 16-11-801 and -802, but not yet appearing in the published Colorado Revised Statutes). Section 16-11-801(1) expressly “reenacted” the pre-1988 statute to the extent it was not “automatically revitalized by operation of law,” and made the pre-1988 law “applicable to offenses committed on or after July 1, 1988, and prior to September 20, 1991.” Section 16-11-801(2) further made House Bill 91S2-1001 applicable to all offenses committed on or after September 20, 1991. Section 16-11-802 sets forth the text of the pre-1988 statute and applies to class one felonies occurring during the period from July 1, 1988 until September 19, 1991.
In addition to inclusion of the fourth step, section 16-11-802 varies from the 1988 statute in that it does not incorporate two amendments made to the 1988 statute in 1989 and 1990. Of significance here, the 1988 statute listed the following as one in a list of aggravating factors: “The defendant committed the offense in an especially heinous, cruel, or depraved manner....” § 16-ll-103(6)(j), 8A C.R.S. (1986). In Cartwright v. Maynard, 822 F.2d 1477 (10th Cir.1987), affd, Maynard v. Cart*188wright, 486 U.S. 356, 108 S.Ct. 1853, 100 L.Ed.2d 372 (1988), the court held that inclusion in the statute of the aggravating factor “heinous, atrocious, or cruel,” without additional definitions of the terms, was impermissible because nothing existed in the aggravator to restrain arbitrary or capricious imposition of the death penalty. 822 F.2d at 1489. Subsequently, in 1989, the Colorado General Assembly added subsection 6.5 to the 1988 statute which defined the terms “cruel,” “depraved,” and “heinous.” S.B. 246, act approved June 8, 1989, ch. 148, sec. 37, § 16-11-103(6.5), 1989 Colo.Sess.Laws 820, 828. We decided People v. Davis, 794 P.2d 159 (Colo.1990), cert, denied, — U.S.-, 111 S.Ct. 662, 112 L.Ed.2d 656 (1991), in 1990 and there analyzed the “cruel, heinous and depraved” aggravator prior to the addition of the statutory definitions, to mean that the defendant “committed the crime in a ‘conscienceless or pitiless’ manner which was ‘unnecessarily torturous to the victim’.” Id. at 176-77. The subsection 6.5 definitions remained part of the death penalty statute from 1989 until 1991. Subsection 6.5 was not included in either House Bill 91S2-1001 or in House Bill 91S2-1038. Instead, House Bill 91S2-1038 listed the aggravator in terms identical to the pre-1988 statute without the subsection 6.5 definitions of those terms.
Additionally, a change was adopted regarding the jury instruction on the availability of parole for a person sentenced to life imprisonment. The 1988 statute read:
For offenses committed before July 1, 1985, the jury shall be instructed that life imprisonment means life without the possibility of parole for twenty calendar years. For offenses committed on or after July 1, 1985, the jury shall be instructed that life imprisonment means life without the possibility of parole for forty calendar years.
§ 16-ll-103(l)(b), 8A C.R.S. (1986). House Bill 91S2-1038 contains identical language. Act approved Oct. 11, 1991, ch. 6, sec. 1, § 16-ll-802(l)(b), 1991 Colo.2d Ex.Sess. Laws, 16, 17. However, in the interim, in 1990, subsection (l)(b) was amended to read: “For offenses committed on or after July 1, 1990, the jury shall be instructed that life imprisonment means life without the possibility of parole.” § 16 — 11— 103(l)(b), 8A C.R.S. (1990 Supp.). By this amendment, the legislature left intact the requirement that the jury shall be instructed of the possibility of parole after twenty years for offenses committed prior to July I, 1985, and the possibility of parole after forty years for offenses committed after July 1, 1985 but before July 1, 1990, affecting only the instruction to be given when an offense is committed after July 1, 1990, as was the offense with which Thomas is charged. To now give effect to section 16-11 — 802(l)(b) would eliminate the impact of the 1990 amendment because section 16-ll-802(l)(b) contains language identical to the 1988 statute before the 1990 amendment.7
After enactment of House Bill 91S2-1038, and in response to the People’s motion, the trial court found that sections 16-11-801 and -802 constituted substantive legislation and their retrospective application violated the ex post facto clause of the Colorado Constitution. Colo. Const, art. II, § 11. The court based its ruling in part on a finding that, because of our decisions in Tenneson and O’Neill, Thomas was on notice at the time he allegedly committed the offenses that no valid death penalty existed in Colorado. As a result, the statutes could not be applied to retroactively increase the applicable punishment to death without violating the ex post facto clause of the Colorado Constitution.
This appeal followed. The People present two issues for our consideration. They assert that the death penalty can be sought against Thomas based on the pre-1988 statute because that statute was revived by operation of law upon the finding that the 1988 death penalty sentencing *189statute was unconstitutional. Additionally, they argue that House Bill 91S2-1038 can be applied to subject Thomas to prosecution with a possibility of a death sentence because sections 16-11-801 and -802 are not substantive legislation and can be retroactively applied without violating the ex post facto clauses of the United States or Colorado Constitutions.
II
The People assert that the pre-1988 statute was effectively “revived” by operation of law after the Young holding in which the 1988 statute was found unconstitutional. The People argue that the doctrine of revival should apply to give effect to the progenitor statute, the pre-1988 statute, as a result of the finding that the 1988 statute was unconstitutional. The trial court declined to revive the pre-1988 statute, stating that to “resurrect” the fourth step would amount to unauthorized “judicial reconstruction” of the death penalty sentencing statute.
A
The doctrine of statutory revival generally operates to reactivate a prior statute which has been replaced by an invalid act:
[A]n unconstitutional statute which purports to repeal a prior statute by specific provision does not do so where, under standard rules governing separability, a hiatus in the law would result from the impossibility of substituting the invalid provisions for the legislation that was to be repealed, or when the repeal is the sole purpose of the enactment.
1A Norman J. Singer, Sutherland Statutory Construction § 23.24, at 396 (4th ed. 1985). We considered this doctrine in White v. District Court, 180 Colo. 147, 503 P.2d 340 (1972). See also Armstrong v. Mitten, 95 Colo. 425, 37 P.2d 757 (1934). In White, we analyzed the effect of an earlier case in which a newly enacted statute which made criminal certain acts relating to passing “bad checks” was held unconstitutional. The legislature replaced the old statute with a new law which, like the 1988 statute at issue here, contained a repeal provision.8 To determine whether to apply the revival doctrine, the test of legislative intent was invoked: “Whether a repeal provision of a legislative act otherwise declared unconstitutional falls with the rest of the act presents a question of legislative intent.” White, 180 Colo, at 149, 503 P.2d at 341. We found that giving effect to the new law’s repeal provision would “create a void in the law relating to bad checks.” Furthermore, realizing that the legislature had historically provided a criminal statute covering bad checks, we concluded that it therefore did not intend the older statute to be repealed if the newer statute was found unconstitutional. The older statute was thus revived by operation of law. White, 180 Colo, at 150, 503 P.2d at 341.9
B
Here, by including a severability clause, the legislature indicated an intent to save *190as much of the 1988 statute as possible upon a finding of unconstitutionality.10 Subsection (8)(a) of the 1988 statute contains the severability provision:
If any provision of this section or the application thereof to any person or circumstances is held invalid or unconstitutional, such invalidity or unconstitutionality shall not affect other provisions or applications of this section, which can be given effect without the invalid or unconstitutional provision or application, and to this end the provisions of this section are declared to be severable.
§ 16-ll-103(8)(a), 8A C.R.S. (1986). By this provision, the legislature authorized a procedure to be implemented upon a finding that the death penalty sentencing statute was unconstitutional.
Wyoming’s procedural death penalty statute contained a severability clause very similar to the one in the Colorado statute. Kennedy v. State, 559 P.2d 1014, 1018 (Wy.1977) (citing § 2, Ch. 136, S.L. of Wyoming 1973). The statute was declared unconstitutional because it imposed a mandatory death penalty for a murder conviction. The court refused to engage in judicial legislation by reading the word “mandatory” out of the statute. Having thus found the section mandating the death penalty unconstitutional, the court looked to the severability provision and found that, since the provisions outlining the steps for imposition of the death penalty were unconstitutional, those provisions were stricken. The court did not engage in revival of the previous death penalty statute but instead gave effect to the severability clause and found that a sentence of life imprisonment should be imposed as the statute provided for such a sentence as a default where death was not appropriate. Id. at 1018-19.
The statutory test for severability is whether the valid provisions of a statute are so essentially and inseparably connected with or dependent upon the void provision that it cannot be presumed that the legislature would have enacted the valid provisions without the void one. § 2-4-204, IB C.R.S. (1980). See also People v. Seven Thirty-Five East Colfax, Inc., 697 P.2d 348, 371 (Colo.1985) (severability clauses “create a presumption that the legislature would have been satisfied with the portions of the statute that remain after the offending provisions are stricken as being unconstitutional”); City of Lakewood v. Colfax Unlimited Ass’n, Inc., 634 P.2d 52, 70 (Colo.1981) (if after striking the unconstitutional provisions, the remainder is so “incomplete or riddled with omissions” that it no longer constitutes a meaningful legislative enactment, the presumption is overcome). Resolution of a sever-ability issue is limited to the four corners of the statute under consideration.
In Young, although we stated that the 1988 version of section 16-11-103 was generally invalid on its face, our conclusion was based on the elimination of the fourth step. Young, 814 P.2d at 846-47. We held that the statute fails to “assure a constitutionally certain and reliable verdict of death under the Colorado Constitution,” id. at 847, but based this holding on a certain feature of the statute — the mandatory imposition of the death penalty when the aggravating and mitigating factors are equally balanced. Id. at 845. Therefore, our decision in Young was not directed at the entirety of the 1988 version of section 16-11-103 but specifically considered whether the absence of the fourth step rendered the determination of sentence procedure unconstitutional.
The jury deliberation process provisions are so intertwined with the remainder of the statute, except for certain provisions in subsection 1(b), that the decision in Young finding them invalid renders most of the remaining provisions unseverable, *191and therefore, also void.11 Our first inquiry is whether, after striking the jury deliberation process provisions, there is enough, meaningful legislation left in the 1988 statute to sustain the presumption of legislative satisfaction.
Subsection 1(b) of the 1988 statute describes, inter alia, the availability of parole when a person is sentenced to life imprisonment. § 16-ll-103(l)(b), 8A C.R.S. (1988 Supp.). The authorized range of penalty upon conviction for a class 1 felony is a minimum of life imprisonment or a maximum of death. § 18 — 1— 105(l)(a)(IV), 8B C.R.S. (1986 & 1991 Supp.). After Young there was no valid jury process for determining whether to impose a death sentence. Once the death option is removed, then the only authorized penalty for conviction of a class 1 felony is life imprisonment. This increases the importance of the provision in subsection 1 which defines the availability of parole upon life imprisonment. We find, therefore, that there does exist some meaningful legislation in the 1988 statute even though the majority of it is invalidated along with the jury deliberation steps.
The existence of this meaningful legislation results in important differences between this case and White. In White, the legislature replaced the entire bad check statute. Conversely, in 1988, the entire death penalty statute was not replaced. Instead, the legislature repealed a specific provision of the pre-1988 statute, which had the effect of amending the jury deliberative process by eliminating the fourth step.
Additionally, unlike the circumstances in White, failure to revive the pre-1988 statute here would not result in a substantive void in criminal prosecutions for class one felonies, but would affect only the punishment options available upon conviction for murder. The alternative sentence of life imprisonment would remain available. The life imprisonment alternative is prescribed by section 18-l-105(l)(a)(IV), 8B C.R.S. (1991 Supp.), which authorizes life imprisonment as the minimum sentence for class one felonies committed after July 1, 1985. This minimum sentence is incorporated in the death penalty procedural statute. It is framed as a “fall-back” when there is infirmity with the imposition of the death sentence:
If any death sentence is imposed upon a defendant pursuant to the provisions of this section and the imposition of such death sentence upon such defendant is held invalid or unconstitutional, said defendant shall be returned to the trial court and shall then be sentenced to life imprisonment.
§ 16-ll-103(8)(b), 8A C.R.S. (1986). The statutory language evinces a legislative intent to substitute the punishment of life imprisonment where the death penalty sentencing scheme is determined constitutionally infirm. To revive the progenitor statute so as to subject Thomas to the possibility of the death penalty under the pre-1988 statute would offend this intent. White does not, therefore, require us to implement the doctrine of revival here. Accordingly, we affirm the trial court’s ruling that Thomas cannot be subjected to the possibility of the death penalty under the pre-1988 statute.
*192III
The trial court found that sections 16-11-801 and -802, as set out in House Bill 91S2-1038, constitute substantive legislation which, under the ex post facto clause of the Colorado Constitution, cannot be applied to Thomas. The People advance the argument that, contrary to the trial court ruling, House Bill 91S2-1038 may be applied to Thomas because it does not constitute legislation which, if retroactively applied, would violate the ex post facto clauses, Article I, § 10 of the United States Constitution, and Article II, § 11 of the Colorado Constitution. Conversely, Thomas contends that the new legislation encompasses changes, which, if applied to him, would violate the constitutional prohibition against ex post facto laws.
A
Both parties argue the applicability of the test for an ex post facto law set forth in the United States Supreme Court decision in Dobbert v. Florida, 432 U.S. 282, 97 S.Ct. 2290, 53 L.Ed.2d 344 (1977), although Thomas asserts that due to a threshold factual difference, we should depart from the rationale in that case. Article II, § 11 of the Colorado Constitution reads:
No ex post facto law, nor law impairing the obligation of contracts, or retrospective in its operation, or making any irrevocable grant of special privileges, franchises or immunities, shall be passed by the general assembly.
(Emphasis added.) Article I, § 10 of the United States Constitution reads, in pertinent part:
No state shall ... pass any bill of attainder, ex post facto law, or law impairing the obligation of contracts....
(Emphasis added.)
As related to different constitutional provisions, this court has departed from the holdings of federal courts under the United States Constitution and held that certain provisions under our state constitution provide our citizens with a higher degree of protection. In People v. Young, 814 P.2d 834, 842 (Colo.1991), we stated that even when the provisions of our state and the United States Constitution are “similarly or identically worded” we have been willing to expand the protections of our citizens under the state constitution. Careful examination of determinations of rights under different provisions reveals that, in some cases, we have considered the different language in the state and federal constitutions as one reason for our differing interpretation. Compare Bock v. Westminster Mall Co., 819 P.2d 55, 58 (Colo.1991) (comparing affirmative language in free speech article under our state constitution with the corresponding article under the United States Constitution), with People v. Young, 814 P.2d at 845 (“[W]e are attentive to the Supreme Court’s reasoning, especially because the cruel and unusual punishments clause in the two constitutions is the same.”).
There is one notable textual difference between the ex post facto clauses of the United States and Colorado Constitutions. The Colorado Constitution prohibits passage of any law “retrospective in its operation.” This clause, however, pertains to civil statutes and does not provide any independent basis for increased protection from retroactive criminal laws, nor does it require departure from the rationale of the federal courts or our prior cases interpreting the ex post facto clause. The retrospective law prohibition is the civil parallel of the ex post facto clause, French v. Deane, 19 Colo. 504, 512-13, 36 P. 609, 612 (1894),12 in that the purpose of both provisions is to prevent “the unfairness entailed in altering the legal consequences of events or transactions after the fact.” People’s Natural GasDiv. v. Public Util. Comm’n, 197 Colo. 152, 155, 590 P.2d 960, 962 (1979). We recognized the dichotomy between the prohibitions against ex post facto laws and *193retrospective laws early in the history of the state:
The phrase ex post facto, as used in the Constitution of the United States, and the Constitutions of the several States, does not apply to civil laws. Such laws only are ex post facto as provide for the punishment of a party for acts ante-cedently done which were not punishable at all, or not punishable to the extent or in the manner prescribed.
Retrospective laws, except such as are ex post facto in the sense above indicated, and such as impair the obligation of contracts, are not in terms inhibited by the Constitution of the United States....
Our Constitution, as we have seen, prohibits the general assembly from enacting: First, ex post facto laws; second, laws impairing the obligation of contracts; third, laws retrospective in their operation.
The fundamental law could not well have been more comprehensive. The term retrospective was intended to apply to laws which could not properly be said to be included in the description of ex post facto, or laws impairing the obligation of contracts.
Denver, South Park & Pacific Ry. Co. v. Woodward, 4 Colo. 162, 163-64 (1878). The only time we have ever addressed the application of the proscription against retrospective laws in the context of a criminal case was in People v. Germany, 674 P.2d 345, 351-52 (Colo.1983). A statute was enacted which, inter alia, prohibited collateral attack of criminal convictions by any person whose conviction antedated the statute by an interval of time in excess of the limitations period. 674 P.2d at 351. We determined that since the statute constituted retrospective elimination of an existing substantive statutory right, id., it could not be “squared with the constitutional prohibition against retrospectively depriving a person of a statutory right without due process of law.” Id. at 352. Our holding, however, focused on the infirmity of the statute under the due process clauses of the United States and Colorado Constitutions, id. at 354, and not on the hybrid constitutional protection against retrospective deprivation of a right without due process. We do not read Germany therefore, as authority for the proposition that the proscription against retrospective laws applies to criminal enactments. Instead, we abide by the dichotomy historically developed that analyzes criminal statutes under the ex post facto clause and civil statutes under the clause prohibiting retrospective legislation.
We have engaged in similar interpretation of civil laws under the retrospective law prohibition as we have criminal laws under the ex post facto clause. That is, retrospective laws are not prohibited if they are deemed only procedural or remedial. Instead, the law is analyzed under certain criteria to determine its effect on vested rights. Continental Title Co. v. District Court, 645 P.2d 1310, 1314-15 (Colo. 1982); California Co. v. Colorado, 141 Colo. 288, 320, 348 P.2d 382, 399 (1959). As the civil parallel of the ex post facto limitation on criminal laws, a retrospective law is one which abrogates or impairs an existing right of action or defense, creates a new obligation, imposes a new duty or attaches a new disability on past transactions or considerations. Martin v. Board of Assessment Appeals, 707 P.2d 348, 351 (Colo. 1985); Evans v. Denver, 26 Colo. 193, 196, 57 P. 696, 697 (1899).
We recognize our freedom to interpret our state constitutional provisions in a manner different than the United States Supreme Court’s interpretations of similar provisions in the United States Constitution. However, we also note that, historically, in defining ex post facto laws, we have analyzed the challenged statute under the criteria set forth by the United States Supreme Court. See Garvey v. People, 6 Colo. 559, 565-66 (1883) (statute found ex post facto under both state and federal constitutions in accordance with precedent of United States Supreme Court, including the “leading case” on ex post facto laws, Calder v. Bull, 3 U.S. (3 Dali.) 386, 1 L.Ed. 648 (1798)); Myers v. District Ct., 184 Colo. 81, 84, 518 P.2d 836, 838 (1974) (“the first and still definitive statement on ex post facto laws is found in Calder v. Bull.... ”); *194Aue v. Diesslin, 798 P.2d 436, 438 (Colo. 1990) (adopting the definition of an ex post facto law as in Calder). Therefore, not persuaded that the prohibition against retrospective laws has any effect on the interpretation of the ex post facto clause in the Colorado Constitution, we will not depart from our past decisions in which we agreed with the United States Supreme Court’s seminal definition of an ex post facto law.13
B
We start, therefore, by examining a factually similar case decided by the United States Supreme Court. In Dobbert v. Florida, 432 U.S. 282, 97 S.Ct. 2290, 53 L.Ed.2d 344 (1977), the defendant was charged with two capital felonies for the murder of his children in December 1971 and early 1972. The defendant was found guilty and the jury recommended life imprisonment. Pursuant to Florida’s death penalty statute then in effect, the judge overruled the jury’s recommendation and sentenced the defendant to death. The sentence was affirmed by the Florida Supreme Court. The United States Supreme Court granted cer-tiorari to consider, inter alia, whether changes in the Florida death penalty statutes subjected Dobbert to trial under an ex post facto law. Dobbert, 432 U.S. at 285-87, 97 S.Ct. at 2294-95. At the time the defendant committed the offenses for which he was convicted, Florida had a death penalty statute that provided that a person convicted of a capital felony, in the absence of a verdict including a recommendation of mercy by a majority of the jury, be punished by death. Several months after the defendant committed the murders, in response to the decision in Furman v. Georgia, 408 U.S. 238, 92 S.Ct. 2726, 33 L.Ed.2d 346 (1972), the Florida Supreme Court struck down the state’s death penalty statute. Late in 1972, before the defendant’s trial, Florida enacted a new death penalty procedure. Dobbert, 432 U.S. at 288, 97 S.Ct. at 2296. Under the new statute, a capital felony trial was bifurcated into a guilt and sentencing phase. During the sentencing phase, certain evidence related to mitigating or aggravating circumstances had to be admitted and any other evidence deemed relevant by the judge could be admitted. The jury would then, by majority vote and based on consideration of the mitigating and aggravating factors, provide the court with a non-binding advisory decision. The court was then required to weigh the aggravating and mitigating circumstances and, if it imposed a death sentence, provide written findings of fact regarding those circumstances.14 Additionally, imposition of a death sentence was subject to automatic, priority review by the Florida Supreme Court. Id. at 290-92, 97 S.Ct. at 2297-98. The new death penalty statute also required persons sentenced to life imprisonment to serve twenty-five years before eligibility for parole. The old statute did not provide that a specified time must be served before parole eligibility. Id. at 298, 97 S.Ct. at 2300-01.
Dobbert’s first ex post facto clause violation claim was premised on the change in the role of the judge and the jury in the imposition of the death sentence. Id. at 292, 97 S.Ct. at 2297-98. Additionally, Dobbert asserted that there was no valid death penalty at the time he committed the crimes because the death penalty in effect at that time was later declared unconstitutional. Id. at 297, 97 S.Ct. at 2300. Dob-bert premised his third ex post facto claim on the change in the parole requirements resulting in the requirement that twenty-five years be served in prison before parole eligibility. Id. at 298, 97 S.Ct. at 2300-01.
Recognizing that “[e]ven though it may work to the disadvantage of a defendant, a procedural change is not ex post facto,” id. at 293, 97 S.Ct. at 2298, the Court readopt*195ed the following standard in determining whether a law is ex post facto:
It is settled, by decisions of this Court so well known that their citation may be dispensed with, that any statute which punishes as a crime an act previously committed, which was innocent when done; which makes more burdensome the punishment for a crime, after its commission, or which deprives one charged with crime of any defense available according to law at the time when the act was committed, is prohibited as ex post facto.
Id. at 292, 97 S.Ct. at 2298 (quoting Beazell v. Ohio, 269 U.S. 167, 169-70, 46 S.Ct. 68, 68, 70 L.Ed. 216 (1925)). Accord Collins v. Youngblood, 497 U.S. 37, -, 110 S.Ct. 2715, 2719, 111 L.Ed.2d 30 (1990). See also Aue v. Diesslin, 798 P.2d 436, 438 (Colo. 1990) (adopting this test in essentially identical language). Applying this standard, the Court held that the change in the role of the court and the jury was procedural. Additionally, the Court found that, to be ex post facto, a law must be more onerous than the prior law. Id., 432 U.S. at 294, 97 S.Ct. at 2298-99. See also Collins v. • Youngblood, 497 U.S. 37, -, 110 S.Ct. 2715, 2718, 111 L.Ed.2d 30 (1990); People v. Billips, 652 P.2d 1060, 1064 (Colo.1982). A separate determination that a change in the law is either ameliorative or that it fails to fit within the definition of a statute violative of the ex post facto clause can provide the basis for a conclusion that there is no ex post facto violation. Dob-bert, 432 U.S. at 292, n. 6, 97 S.Ct. at 2298, n. 6. In Dobbert, the Court found that the effect of the new statute altering the role of the jury and the judge was procedural because it “simply altered the methods employed in determining whether the death penalty was to be imposed,” and did not affect either the crime, punishment for the crime, or degree of proof necessary to establish guilt. Id. at 292-94, 97 S.Ct. at 2297-99. In addition, the Court found that this change was ameliorative because it provided capital defendants with greater protection against arbitrary imposition of the death penalty by providing defendants with “a second chance for life with the trial judge....” Id. at 296, 97 S.Ct. at 2300. As a result, the Court held there was no ex post facto violation.
Addressing Dobbert’s argument that no death penalty was “in effect” in Florida at the time he murdered his children, the Court held that the existence of the death penalty statute determined unconstitutional after Furman “provided fair warning,” and “served as an ‘operative fact’ to warn [Dobbert] of the penalty which Florida would seek to impose on him if he were convicted of first-degree murder.” Id. at 297-98, 97 S.Ct. at 2300.
Lastly, the Court held that Dobbert could not complain about the change in the parole eligibility requirement because, since he was sentenced to death, not to life imprisonment, this change would have no effect on him. Id. at 298-301, 97 S.Ct. at 2300-02.
C
The dissenters in Dobbert proposed that the “touchstone” of the majority opinion was the presence of “fair warning” of the possibility of the death sentence. Id. at 305-07, 97 S.Ct. at 2304-05 (Stevens, J., dissenting, joined by Brennan and Marshall, JJ.). The dissent asserted that the majority holding represented a clear departure from past cases construing the ex post facto clause and, alternatively, urged adherence to the test set forth in Lindsey v. Washington, 301 U.S. 397, 401, 57 S.Ct. 797, 799, 81 L.Ed. 1182 (1937):
The Constitution forbids the application of any new punitive measure to a crime already consummated, to the detriment or material disadvantage of the wrongdoer.
Stating that “fair warning” does not provide a workable test, the dissent focused on the ex post facto clause protection “against improperly motivated or capricious legislation,” and reiterated the concern of Justice Harlan in James v. United States, 366 U.S. 213, 247 n. 3, 81 S.Ct. 1052, 1070 n. 3, 6 L.Ed.2d 246 (1961), that the result of ex post facto legislation may not be to deter dangerous conduct but, instead, to target *196specific persons or classes of persons. Dobbert, 432 U.S. at 307 n. 7, 97 S.Ct. at 2305 n. 7. Some scholars in the field of constitutional law have agreed with the dissent in Dobbert because it highlights the potential for enactment of abusive legislation affecting an already identifiable group. See John E. Nowak, Ronald D. Rotunda & J. Nelson Young, Constitutional Law 478 (2d ed. 1983). Yet, not all commentators subscribe to this criticism. Professor Laurence H. Tribe has stated:
[I]t seems sounder, on reflection, to treat the Dobbert court’s inattention to [the] theoretical risk of legislative abuse as reflecting only the absence of any actual risk of this sort in the case at hand. For long before Dobbert’s arrest in early 1973, and well before he was tried and sentenced, later that year, the new death penalty provision — enacted in late 1972— was safely in place. Those who enacted it to cure the constitutional flaws in the prior procedure might conceivably have been aware of the crime at issue, but there is no reason to suspect they were aware of the criminal. And although the capital punishment law in effect at the time he acted had been changed by the time he was tried and sentenced, the Court seems correct in its conclusion that the change was, on the whole, an ameliorative one — making the death penalty more difficult to inflict. Dobbert therefore should not be read to stand for the proposition that, so long as an individual is given fair warning, the legislature may deliberately design a crime — or a punishment — to fit the criminal.
Laurence H. Tribe, American Constitutional Law § 10-3, 640 (2d ed. 1988) (footnotes omitted). Although Thomas’ arrest was secured prior to enactment of House Bill 91S2-1038, he was not an identifiable target of this legislation because he was not convicted of any crime securing his eligibility for the imposition of death. Concern about legislative targeting of certain individuals for imposition of the death sentence is overly presumptuous where, as here, those persons are considered innocent of any crime until proven guilty. Thus, as of the time of the enactment, the legislature did not know of any persons who would be necessarily subjected to a sentencing hearing with the possibility of a death sentence.15
*197In Weaver v. Graham, 450 U.S. 24, 28, 101 S.Ct. 960, 964, 67 L.Ed.2d 17 (1981), the Court stated that the purpose of the ex post facto clause was to assure that “legislative Acts give fair warning of their effect and permit individuals to rely on their meaning until explicitly changed.” While fair warning may well have been the Framers’ purpose in adopting the ex post facto clause, subsequent judicial interpretation, mindful of such purpose, has refined the definition of an ex post facto law.
Thomas relies on the fair warning test in Dobbert and argues that Dobbert is inapplicable because, contrary to Dobbert, prior to ■the time he allegedly committed the offenses in February 1991, he was on notice that Colorado’s death penalty statute was unconstitutional by virtue of our decisions in People v. Tenneson, 788 P.2d 786 (Colo. 1990), and People v. O’Neill, 803 P.2d 164 (Colo.1990). Thomas argues that it was critical to the holding of Dobbert that the accused was on notice at the time of the crime that a death sentence was a possibility. See Dobbert, 432 U.S. at 297, 97 S.Ct. at 2300. The trial court agreed with Thomas, finding that in Tenneson we alerted the state as a whole to the constitutional infirmities of the 1988 statute. Furthermore, the court found that in O’Neill we stated that the absence of the fourth step was constitutional error requiring reversal and that until the 1988 statute was amended or repealed, life imprisonment was the only sentencing option in Colorado upon conviction for first degree murder. As a result, House Bill 91S2-1038 inflicts a greater punishment than the law in effect at the time of the act and violates the proscription against ex post facto laws.
We are of a contrary view. In Colorado, a statute is presumed to be constitutional. Such presumption was statutorily in place at the time Thomas allegedly committed his offense. § 2-4-201, IB C.R.S. (1980). This presumption is not overcome until the party challenging it proves unconstitutionality beyond a reasonable doubt. People v. Loomis, 698 P.2d 1320, 1321 (Colo.1985). In neither Tenneson nor O’Neill did we address the constitutionality of the 1988 statute. Both cases were decided under the pre-1988 statute, which required a fourth step. See Tenneson, 788 P.2d at 789-96; O’Neill, 803 P.2d at 176 and n. 14. We disagree with Thomas’ assertion that prior to February 1991, the time he allegedly committed murder, we “told,” “pronounced,” or “published” a finding that the 1988 death penalty statute was unconstitutional. While we did construe and analyze the importance of the fourth step as contained in the pre-1988 statute there at issue, we did not consider the 1988 statute, let alone hold it unconstitutional, until our decision in Young.
In a case decided in 1990, based on the plain language of the statute regarding parole for sex offenders, we reversed the parole board’s interpretation of that statute and held that sexual offenders were not subject to mandatory but to discretionary parole. See Thiret v. Kautzky, 792 P.2d 801 (Colo.1990). As a result, in Aue v. Diesslin, 798 P.2d 436, 441 (Colo.1990), we held that a defendant who had been imprisoned prior to the Thiret decision was not eligible for mandatory parole, but that the parole board had discretion to determine parole eligibility. The defendant argued that application of the Thiret decision constituted a violation of the ex post facto clause. Addressing the problem as a due process issue, we held that the Thiret decision was retroactively applicable because it was “sufficiently foreseeable so that the defendant had fair warning that the interpretation given the relevant statute by the court would be applied in his case.” Aue, 798 P.2d at 441. The factor that we relied on to establish the reasonable foreseeability of the Thiret decision was that the decision was based on the plain language of the statute and that the parole board had erroneously interpreted the clear, unambiguous statute. Thomas asserts that *198pursuant to Aue, he was on sufficient notice of the unconstitutionality of the 1988 statute at the time he allegedly committed murder so as to render that statute inapplicable to him. ■ Yet, because the Young decision was not based on any clear statutory language but rather was the result of an involved analysis of constitutional decisions from both our jurisdiction and the United States Supreme Court, Aue is inapplicable here.
Therefore, if Thomas was on notice as he claims, it was the result of conjecture on his part and such conjecture cannot serve as the basis for a legally sufficient argument here. Consequently, since the offense with which Thomas is charged occurred prior to our holding in Young, we do not find that he was on notice that the death penalty statute was unconstitutional, but rather find that, as in Dobbert, he had fair warning that the death penalty was a possible punishment for first degree murder.
Fair warning is an important aspect of Dobbert. In part, the historic Calder test defines as ex post facto “fejvery law that changes the punishment, than the law annexed to the crime, when committed.” Calder v. Bull, 3 U.S. (3 Dali.) 386, 390, 1 L.Ed. 648 (1798). Dobbert refines the scope of this test by providing a means to determine what law is annexed to the crime at the time it is committed. Dobbert argued that the void ab initio doctrine was implicated and, since the death penalty statute in effect at the time he murdered his children was later found unconstitutional, there was no effective death penalty in Florida at the time of the crimes. The Court determined that, where a party has fair warning of the existence of a statute, that warning constitutes an “operative fact” which justifies application of a subsequently enacted statute which imposes the same punishment as the statute which has been stricken. Dobbert, 432 U.S. at 297-98, 97 S.Ct. at 2300. Because fair warning of the possibility of the punishment provided for- by the statute judicially invalidated is an “operative fact” constituting “sufficient compliance with the ex post facto provision ..we read Dobbert as holding that for purposes of the Calder test, the law annexed to a crime which antedates a finding of statutory unconstitutionality is the punitive statute later determined invalid by the judiciary. Therefore, if the subsequent punitive statute does not authorize a more onerous punishment than the punishment authorized by the judicially invalidated statute, the subsequent statute may be retroactively applied. Id. at 298, 97 S.Ct. at 2300. Under this theory, the law annexed to the offense that Thomas allegedly committed was the 1988 statute.
D
In a recent case, Collins v. Young-blood, 497 U.S. 37, 110 S.Ct. 2715, 111 L.Ed.2d 30 (1990), the Court overruled two very early cases concerning the ex post facto clause. In Kring v. Missouri, 107 U.S. 221, 2 S.Ct. 443, 27 L.Ed. 506 (1883), a new Missouri constitution, incorporating a change affecting the state’s ability to retry the defendant, was found to violate the ex post facto clause because it altered “the situation of a party to his disadvantage.” Kring, 107 U.S. at 228-29, 2 S.Ct. 443. The Collins Court overruled Kring, finding that this expansive definition constituted an unjustified departure from the definition of an ex post fact law as set out in Calder v. Bull, 3 U.S. (3 Dali.) 386, 391, 396, 1 L.Ed. 648 (1798). Collins, 497 U.S. at-, 110 S.Ct. at 2722-23. In Thompson v. Utah, 170 U.S. 343, 18 S.Ct. 620, 42 L.Ed. 1061 (1898), the Court reversed the defendant’s conviction, finding that a change in the number of jurors in a capital case, as the result of adoption of a new constitution, “deprived him of a substantial right involved in his liberty” and materially altered the situation to his disadvantage. Thompson, 170 U.S. at 352-53, 18 S.Ct. at 623. Surveying the historical development of the law regarding the ex post facto clause, the Collins Court attempted to clarify the confusion it felt had resulted from Thompson which held that if a change affects “substantial protections,” it is viola-tive of the clause. Id., 497 U.S. at-, 110 S.Ct. at 2720-21. Instead, the Collins Court found that, while a right to a jury *199trial is obviously "substantial,” “it is not a right that has anything to do with the definition of crimes, defenses, or punishments, which is the concern of the Ex Post Facto Clause.” Collins, 497 U.S. at-, 110 S.Ct. at 2723-24.
While thus overruling eases that expanded the definition of an ex post facto law, the Collins Court examined the defendant’s argument that a change in a Texas statute allowing reformation of an improper jury verdict violated the ex post facto clause of the United States Constitution. Noting that the labelling of a law as “procedural” by the legislature “does not thereby immunize it from scrutiny under the Ex Post Facto Clause,” the Court also rejected the notion that simply because a statute is alleged to affect a “substantial protection” or “personal right” it violates the clause. Id. 497 U.S. at -, 110 S.Ct. at 2721. Consequently, the Court did not engage in labelling the change in the Texas statute as substantive or procedural but instead reverted to the long accepted standard of which retroactive changes are prohibited as was set forth in Dobbert, and found that application of the Texas statute to the defendant did not violate the ex post facto clause. Id. 497 U.S. at-, 110 S.Ct. at 2724. The result of the Collins decision arguably constricts the historical protection against ex post facto legislation. In overruling two early precedents, stating that they were inconsistent with the understanding of the term “ex post facto” at the time of the adoption of the United States Constitution, the Collins court attempted to rein in the definition of an ex post facto law and prevent the development of a body of law based not on the seminal definition of an ex post facto law as set forth in Calder v. Bull, but rather on examination of two elusive terms — whether a change constitutes a “substantial protection,” or alters “the situation of a party to his disadvantage.” 497 U.S. at-, 110 S.Ct. at 2720-24. Collins, for our purposes, does little more than affirm the decision in Dob-bert, which relied solely on the definition of an ex post facto law as set forth in Calder v. Bull. (.Dobbert quoted the language of Beazell v. Ohio, 269 U.S. 167, 169-70, 46 S.Ct. 68, 68-70, 70 L.Ed. 216 (1925), which adopted the Calder test). Since the statutes at issue here can be tested under a Calder analysis, it is unnecessary for us to consider Collins to determine whether we should apply it for the purpose of defining whether the ex post facto clause of the Colorado Constitution still prohibits laws which affect “substantial protections,” or disadvantageously alter the situation of a party.
Guided then by the historical Calder test for an ex post facto law, we also decline to focus on whether House Bill 91S2-1038 constitutes substantive as opposed to procedural legislation. Instead, the legislation is examined under the standard that the ex post facto clause is violated when a statute punishes as a crime conduct which was innocent when done, makes more onerous the punishment for a crime after its commission, or deprives a defendant of a defense that was available at the time the crime was committed.16
Thomas asserts that enactment of House Bill 91S2-1038 resulted in two specific changes to the death penalty law which are violative of the ex post facto clauses. First, he argues that the failure to enact language in section 16-11-802 similar to the 1990 amendment prohibiting parole for persons convicted of class 1 felony offenses committed after July 1, 1990, § 16-ll-103(l)(b), 8A C.R.S. (1990), constitutes a substantive change because it eliminates a defense to the death penalty — the guarantee that if the jury chooses not to impose death, the defendant will remain incarcerated for the rest of his life. Section 16-11-802 reverts to the language of the statute before the amendment in 1990 and provides that the jury be instructed *200that a sentence to life imprisonment means the possibility of parole after forty years for offenses committed after July 1, 1985. We find this change ameliorative and, therefore, incapable of violating the ex post facto clauses.
We do not agree with Thomas’ categorization of this change as a loss of a “defense.” We agree with the Supreme Court that “[a] law that abolishes an affirmative defense of justification or excuse contravenes [the ex post facto clause] because it expands the scope of a criminal prohibition after the act is done.” Collins v. Young-blood, 497 U.S. 37, -, 110 S.Ct. 2715, 2723, 111 L.Ed.2d 30 (1990). That, however, is not the case here. Thomas asserts that this change is detrimental because a jury is more likely to impose the death penalty if they are instructed that failure to impose such penalty, and instead to impose a life sentence, means that a defendant could be paroled after forty years. We are not convinced by this argument which involves sheer speculation about the effect of an obviously ameliorative change on the psyche of the jury. This change indisputably benefits a defendant convicted of a class one felony by making possible parole after forty years — as opposed to the 1990 amendment that provided no possibility of parole for those convicted of offenses occurring after July 1, 1990. This change, therefore, cannot provide the basis for an ex post facto challenge.
Second, Thomas asserts that the change in the elements of the statutory aggravator “cruel, heinous, or depraved,” as a result of the failure to include the definitions previously set out in subsection 6.5 of the 1988 statute, as amended in 1989 by Senate Bill 246, constitutes a change detrimental to him. See Act approved June 8, 1989, ch. 148, sec. 37, 1989 Colo.Sess. Laws 820, 828. In People v. Davis, 794 P.2d 159, 176-77 (Colo.1990), cert, denied, — U.S. -, 111 S.Ct. 662, 112 L.Ed.2d 656 (1991), we narrowed the definition of this aggravator, holding that it is proved by a showing that the crime was committed in a “ ‘conscienceless or pitiless’ manner which was ‘unnecessarily torturous to the victim.’ ” See Proffitt v. Florida, 428 U.S. 242, 255, 96 S.Ct. 2960, 2968, 49 L.Ed.2d 913 (1976) (adopting a construction upon which our definition of the aggravator in Davis was based). Specifically, Thomas asserts that the definitions in subsection 6.5 were more precise and that failure to reenact this subsection constitutes an easing of the state’s burden in proving the aggravator, triggering the ex post fac-to clause.
We first examine whether failure by the legislature to specifically enact language equivalent to the limiting construction adopted in Davis renders this judicial definition no longer applicable as a limitation on the terms of the aggravator. “Words and phrases that have acquired a technical or particular meaning, whether by legislative definition or otherwise, shall be construed accordingly.” § 2-4-101, IB C.R.S. (1980). Furthermore, it is presumed that the legislature “is cognizant of and adopts the construction which prior judicial decisions have placed on particular language when such language is employed in subsequent legislation.” Thompson v. People, 181 Colo. 194, 200, 510 P.2d 311, 313 (1973). Therefore, we find that because section 16-11-802 did not contain the statutory definition of the terms, the legislature adopted the Davis construction of the statutory ag-gravator “cruel, heinous and depraved” when it enacted House Bill 91S2-1038.
Next examining whether this change is detrimental to Thomas, we agree that the statutory definitions set forth in subsection 6.5 were more precise than the judicial definition of the aggravator terms set forth in Davis. However, diversion from a more detailed definition of an aggravator does not equate with detrimental change. Section 16-11-103(6.5), 8A C.R.S. (1989 Supp.), read:
For the purposes of paragraph (j) of subsection (6) of this section, the following definitions shall apply:
(a) “Cruel” means intentional infliction of physical or psychological torture, and includes the pitiless infliction of pain or suffering with utter indifference to, or *201the enjoyment of, the suffering of others.
(b) “Depraved” means senseless or committed without purpose or meaning, or that the murder was not the product of greed, envy, revenge, or another of those emotions ordinarily associated with murder, and served no purpose for the defendant beyond his pleasure of killing.
(c) “Heinous” means using a particularly shocking or brutal method of killing, or a killing in which the victim is unable to physically defend himself because of physical or mental disability or because he is too old or too young.
“Unnecessarily torturous,” must be proven to satisfy the test set forth in the judicial definition. This term is encompassed within the subsection 6.5 definition of “heinous.” Either “conscienceless” or “pitiless” must also alternatively be proven under the judicial definition, as evidenced by the use of the word “or.” “Conscienceless” is encompassed within the statutory definition of “cruel” by the term “utter indifference.” “Pitiless” is encompassed within the statutory definition of “cruel.” By use of the term “or,” the judicial definition of the aggravator set out in Davis requires proof of conduct that is both unnecessarily torturous and either conscienceless or .pitiless. Conversely, the aggravator as limited by subsection 6.5, as a result of inclusion of the word “or,” requires only that any one of the three types of behavior alternatively be shown — “cruel, heinous or depraved.” The prosecution, under the judicial definition, therefore, has the more difficult task of proving the aggravator. by presenting evidence of two of the three types of conduct. This consolidation of terms under the judicial definition is, therefore, beneficial to defendants.
Additionally, under subsection 6.5, the prosecution had the option of proving the aggravator by showing that the defendant acted with a motive not normally associated with murder, pursuant to the definition of “depraved.” There is no corresponding limitation in the judicial definition of the aggravator. Under the statute as now limited by judicial definition, this option for the prosecution is deleted, thus narrowing the prosecution’s ability to prove the existence of cruel, heinous or depraved conduct. Accordingly, since this change does not result in disadvantage to Thomas, it also cannot provide the basis for an ex post facto challenge.17
E
Having determined that these two changes do not provide grounds for a finding that section 16-11-802 violates the ex post facto clause, we examine the new statute as a whole.18 Section 16-11-802 rein*202states the fourth step, which was not part of the statute in place at the time it is alleged Thomas committed murder. This fourth step requires a jury to engage in an additional step before it can sentence a defendant to death, and thus obviously benefits a defendant. Furthermore, it does not violate the test set forth in Dobbert because, at the time Thomas allegedly committed the offense, the 1988 death penalty statute had not been ruled invalid and thus the punishment for a class one felony has not increased from the punishment available under the law annexed to the crime when committed. The existence of the effective death penalty statute and fair warning of the possibility for the death penalty constituted “operative facts” to establish “sufficient compliance” with the ex post facto clause. See Dobbert, 432 U.S. at 298, 97 S.Ct. at 2300. Secondly, the statute neither deprives a criminal defendant of a defense nor punishes as a crime conduct which was innocent when it occurred. The statute can, therefore, be applied without violating the ex post facto clauses.
IV
Finally, Thomas argues that retroactive application of House Bill 91S2-1038 would violate his constitutional guarantees to equal protection, due process of law, effective assistance of counsel and protection against cruel and unusual punishment. These arguments are premised on Thomas’ assertion that because his trial was delayed due to his counsel’s zealous advocacy, he is now subject to the death penalty. He claims that, if his counsel had foregone the competency determination, he would already have been tried, and even if convicted and sentenced to death, that sentence would have been reversed and life imprisonment alternatively imposed pursuant to section 16-ll-103(8)(b), 8A C.R.S. (1986) (unchanged and part of the 1988 statute):
If any death sentence is imposed upon a defendant pursuant to the provisions of this section and the imposition of such death sentence upon such defendant is held invalid or unconstitutional, said defendant shall be returned to the trial court and then shall be sentenced to life imprisonment.
First we note that, because Thomas has not yet been tried, convicted or sentenced, he again engages in speculation in alleging an injury under these constitutional provisions. Nonetheless, we address and dispose of these arguments summarily.
As to Thomas’ equal protection argument, we adopt the reasoning in Dob-bert, 432 U.S. at 301, 97 S.Ct. at 2302:
[Pjetitioner is simply not similarly situated to those whose sentences were commuted. He was neither tried nor sentenced prior to [the case finding the Florida death penalty statute unconstitutional], as were they, and the only effect of the former statute was to provide sufficient warning of the gravity Florida attached to first-degree murder so as to make the application of this new statute to him consistent with the Ex Post Facto Clause of the United States Constitution. Florida obviously had to draw the line at some point between those whose cases had progressed sufficiently far in the legal process as to be governed solely by the old statute, with the concomitant unconstitutionality of its death penalty provision, and those whose cases involved acts which could properly subject them to punishment under the new statute. There is nothing irrational about Florida’s decision to relegate petitioner to the *203latter class, since the new statute was in effect at the time of his trial and sentence.
Additionally, we do not find that, even if Thomas were sentenced to death, his constitutional right to due process and protection against cruel and unusual punishment would be violated. See People v. Davis, 794 P.2d 159, 170-75 (Colo.1990), cert. denied, — U.S. —, 111 S.Ct. 662, 112 L.Ed.2d 656 (1991) (death penalty does not violate either of these constitutional protections). Since proceedings in the trial court have been stayed pending our determination, Thomas will be aware well in advance of trial of the possibility of imposition of the death penalty and will, therefore, be able to make tactical decisions for trial consistent with this knowledge. See Coleman v. McCormick, 874 F.2d 1280, 1289 (9th Cir.), cert, denied, 493 U.S. 944, 110 S.Ct. 349, 107 L.Ed.2d 337 (1989) (court found due process violation when defendant sentenced under death penalty statute enacted after his trial, based on finding that the defendant’s counsel made “countless tactical decisions at trial aimed solely at obtaining ... acquittal, without even a hint that evidence in the record would be considered as either mitigating or aggravating factors”).
Lastly, Thomas makes the contorted argument that by exposing him to the possibility of a death sentence, we are in essence denying him his right to effective assistance of counsel by encouraging counsel in death cases to act in a nondiligent and ineffective manner in relation to pretrial matters so as to hasten the start of trial. Thomas misconstrues this constitutional right. The right to effective assistance of counsel guarantees defendants just that — reasonably effective assistance of attorneys — and Thomas’ argument that he was detrimentally affected by representation which he admits was zealous and diligent fails to state proper grounds for this allegation. See People v. Bossert, 722 P.2d 998, 1010 (Colo.1986). We have previously recognized that a court’s interference with an attorney’s ability to effectively represent a defendant does provide a defendant with a claim for ineffective assistance of counsel. See e.g., People v. Scales, 763 P.2d 1045, 1048 (Colo.1988) (after substitution of counsel, denial of adequate time for new counsel to prepare for trial would provide defendant with claim for ineffective assistance). Here, however, by applying House Bill 91S2-1038 and providing counsel with sufficient time to prepare for a trial at which the death penalty may be sought against their client, we are not engaging in any interference with counsel’s ability to effectively represent Thomas.
Accordingly, we reverse the second order of the district court and remand with an instruction to allow the prosecution to seek the death penalty against Thomas pursuant to section 16-11-802.
ROVIRA, C.J., delivered the Opinion of the Court with respect to Parts II and IV.
ERICKSON, J., specially concurred as to Part II.
KIRSHBAUM and VOLLACK, JJ., filed dissents as to Part II.
ROVIRA, C.J., announced the Judgment of the Court and delivered an Opinion with respect to Part III, in which VOLLACK, J., joined.
ERICKSON, J., filed a specially concurring opinion as to Part III.
MULLARKEY, J., filed an opinion concurring in the judgment as to Part III.
LOHR, J., filed a dissent as to Part III, which QUINN, J., joined in its entirety and KIRSHBAUM, J., joined in Parts I, II, and III thereof.
.Since the pre-1988, the 1988, and the 1991 death penalty sentencing statutes are all codified at section 16-11-103 (the 1988 and 1991 statutes really only constituting amendments to the pre-1988 statute), it is important to differentiate these provisions by providing them with different labels. Because an understanding of the evolving legislation is critical to an understanding of this opinion, the following synopsis is provided at the outset for reference:
1. "Pre-1988 statute” refers to section 16 — 11— 103, 8A C.R.S. (1986), which set forth a four step process for jury deliberations in determining whether to impose a sentence of life imprisonment or a sentence of death.
2. "1988 statute" also refers to section 16 — 11— 103, 8A C.R.S. (1988 Supp.), but the reference is to the death penalty sentencing statute as amended by Senate Bill 78 in 1988. Section 3 of this Bill eliminated the fourth step in the jury deliberation process by repealing the provision in the pre-1988 statute which set forth this step.
3. "House Bill 1001" also refers to section 16-11-103, and is the label for the death penalty sentencing statute as amended in September 1991. Act approved Sept. 20, 1991, ch. 4, sec. 1, § 16 — 11—103, 1991 Colo.2d Ex.Sess. Laws 8. This provision again reenacts the fourth step and is applicable to class one felony offenses occurring on or after September 20, 1991.
4."House Bill 1038” refers to two new statutes enacted in October, 1991 — sections 16-11-801 and 16-11-802.
A. Section 16-11-801 states that the pre-1988 statute is reenacted to the extent it was not revitalized upon a finding that the 1988 statute was unconstitutional.
B. Section 16-11-802 is yet another death penalty sentencing statute which is essentially identical to the pre-1988 statute (with certain changes as discussed in the text) and is applicable to class one felonies which occur from July 1, 1988 until September 19, 1991. Act approved Oct. 11, 1991, ch. 6, sec. 1, 1991 Colo.2d Ex.Sess.Laws 16.
. The People filed an amended petition for a writ of mandamus, request for a rule to show cause, request for a stay of proceedings in the trial court and a notice of appeal pursuant to section 16-12-102(1), as amended by H.B. 91S2-1008, ch. 5, sec. 1, 1991 CoIo.2d Ex.Sess.Laws 15. By order of this court dated November 7, 1991, the original proceeding pursuant to C.A.R. *18521 and the notice of appeal were joined and the proceedings in the trial court were stayed.
. The offenses were committed prior to the effective dates of the amendments which constitute the 1988 statute.
. Specifically, the original information filed in the district court charged Thomas with the following crimes committed against an elderly woman: 1) first degree murder after deliberation under § 18-3-102(1); 2) first degree felony murder pursuant to § 18-3-102(l)(b); 3) first degree sexual assault under § 18-3-402; 4) second degree burglary as defined in § 18-4-203; 5) aggravated robbery pursuant to § 18-4-302(1)(b), and; 6) robbery of the elderly under §§ 18-4-301 and -304.
. A preliminary hearing first occurred in March 1991. After the court found probable cause that the crimes alleged were committed and that Thomas committed those crimes, arraignment was set for April. However, the arraignment did not take place until July because at the time set for the April arraignment the defense requested a competency determination and Thomas was evaluated at the Colorado State Hospital. In May, during a proceeding to set a hearing date for a final determination of competency, the People informed the court and Thomas of their intent to seek the death penalty. The defense withdrew the request for a final determination of competency in July 1991. Later that month, Thomas was arraigned and entered a plea of not guilty to the charge of first degree murder. Trial was set for December 1991, which date was subsequently vacated pending this appeal.
. The record discloses that Thomas waived his right to formal advisal and tendered a plea of not guilty to the information. The minute order issued after the entry of this plea reflected that the court received "defendant’s plea of 'not guilty’ to the one count information." This results in confusion over the correctness of the minute order reference to a one-count information since Thomas was charged with several other offenses related to the murder charge. See supra n. 4. However, since the charge of first degree murder alone is sufficient to subject Thomas to the possibility of a jury imposing a death sentence, for the purposes of this opinion, we need not definitively resolve the question surrounding the disposition of the other charges.
At this July hearing, Thomas was also charged with an additional crime — arson pursuant to § 18-4-102, 8B C.R.S. (1986). The arson charge relates to an incident that took place at the Adams County Jail on June 18, 1991. The record contains no further information about this crimé.
. House Bill 91S2-1001, section 16 — 11— 103(l)(b), ch. 4, sec. 1, 1991 Colo.2d Ex.Sess. Laws 8, contains a change similar to that in section 16 — 11—802(l)(b). However, it is the statute enacted to cover the hiatus period, section 16-11-802, enacted by House Bill 91S2-1038, that is relevant here.
. Sections 2 and 3 of S.B. 78, ch. 114, 1988 Colo.Sess.Laws 673, 675, specifically provided for repeal of §§ 16 — 11—103(2)(b)(II) and (2)(a)(III), 8A C.R.S. (1986), respectively.
. The effect of Article V, Section 24 of the Colorado Constitution was not raised in White. Thomas argues that this constitutional provision prohibits revival of a statute unless the legislature re-enacts and republishes in full the old law. This section reads: "No law shall be revived, or amended, or the provisions thereof extended or conferred by reference to its title only, but so much thereof as is revived, amended, extended or conferred, shall be re-enacted and published at length." We are not convinced by this argument because Article V as a whole, and section 24 particularly, presents constitutional limitations on the legislative department, not applicable limits on our judicial powers. See Edwards v. Denver & Rio Grande R.R. Co., 13 Colo. 59, 65-66, 21 P. 1011, 1013 (1889). The purpose of section 24 of Article V has been interpreted to be the prevention of any confusion which would result from the amending of statutes by reference to the title only or without restating the parts amended. Thiele v. City & County of Denver, 135 Colo. 442, 454, 312 P.2d 786, 793 (1957). The doctrine of revival argued here, however, has little to do with the scripting of statutory changes by the legislature, but instead, as set forth in White, is a function which enables the judicial branch to promote legislative intent. Accordingly, the appropriateness of invoking the doctrine of judicial revival is analyzed under the legislative intent test set forth in White.
. The severability clause, section 16 — 11— 103(8)(a), was added to the death penalty sentencing statute by House Bill 1310 in 1984 and has remained part of the death penalty statute since that time without further amendment. Act approved April 12, 1984, ch. 120, sec. 5, 1984 Colo.Sess.Laws 491, 495. Consequently, this severability clause applies to the death penalty sentencing statute as amended in 1988 and as amended in 1991. For purposes of determining whether to revive the pre-1988 statute, however, it is the effect of the severability clause on the repeal provision of the 1988 statute that is relevant here.
. Subsection 1(a) of the 1988 statute provides for a separate sentencing hearing when a person is convicted of a class 1 felony; for a maximum sentence of life imprisonment where the defendant is under eighteen years of age; sets forth the role of the alternate juror during the sentencing phase, § 16-ll-103(l)(a), 8A C.R.S. (1986); and describes the types of evidence to be received at the sentencing hearing. Yet, if the death penalty cannot be imposed by virtue of the invalidity of the jury process provisions, then these provisions of subsection 1 are meaningless. Subsection 3 of the 1988 statute provides that where trial is to the court, the court shall follow the same procedures as a jury would in making a determination of whether to impose the death sentence. Subsection 4 was repealed in 1984. Subsections 5 and 6 set forth statutory mitigating and aggravating factors to be balanced in making a sentencing determination. Subsection 7 provides for appellate supreme court review when a death sentence is imposed. Subsection 8(a) is the severability clause as above and 8(b) provides for a resen-tencing to life of any person sentenced to death pursuant to this statute whose death penalty is subsequently determined to be invalid. § 16-11-103(3) to (8), 8A C.R.S. (1986 & 1988 Supp.).
. In French, the court, in referring to Article II, section 11 of the Colorado Constitution, also said: “The word retrospective as here used has reference to civil cases, and as to such cases it is synonymous with the term ex post facto, as applied to the criminal law." French, 19 Colo. at 512-13, 36 P. at 612.
. We are not alone in finding that the United States Supreme Court’s interpretation of the federal ex post facto clause is persuasive authority in interpreting a state ex post facto clause where the language of the two clauses is parallel. See e.g. Tichnell v. State, 287 Md. 695, 415 A.2d 830, 851 (1980).
. Since the jury’s recommendation was not binding under the new statute, a judge had the choice of imposing a life sentence even when the jury recommended death. Dobbert, 432 U.S. at 296, 97 S.Ct. at 2300.
. Despite the presence of such criticism, Dob-bert has found support in other jurisdictions which have found no ex post facto clause violation in accordance therewith and focus on whether the legislative change is either ameliorative or onerous, or affects substantive or procedural rights. See e.g., Ex parte Hays, 518 So.2d 768, 775 (Ala. 1986), cert, denied, 485 U.S. 929, 108 S.Ct. 1099, 99 L.Ed.2d 262 (1988) (because the change did not alter the quantum of punishment attached to the crime, no ex post facto violation when judicially constructed rule allowing court to overrule jury recommendation of life imprisonment was retroactively applied); State v. Watson, 120 Ariz. 441, 453-54, 586 P.2d 1253, 1265-66 (1978), cert, denied, 440 U.S. 924, 99 S.Ct. 1254, 59 L.Ed.2d 478 (1979) (quoting Dobbert at length and finding no ex post facto violation because change to Arizona statute procedural); Pickens v. State, 292 Ark. 362, 730 S.W.2d 230, 235 cert, denied, 484 U.S. 917, 108 S.Ct. 269, 98 L.Ed.2d 226 (1987) (change in death penalty sentencing scheme not ex post facto because it affected neither the crime, punishment prescribed, nor degree of proof necessary to establish guilt); Tichnell v. State, 287 Md. 695, 415 A.2d 830, 851-52 (1980) (statutory changes procedural and ameliorative and therefore, not ex post facto); Belt v. State, 353 So.2d 1141, 1143-44 (Miss.1977) (relying on Dobbert for ex post facto analysis and finding no violation where judicial changes in death penalty process were procedural and ameliorative and could be applied retroactively); State v. Coleman, 185 Mont. 299, 605 P.2d 1000, 1010-1012 (1979), cert, denied, 446 U.S. 970, 100 S.Ct. 2952, 64 L.Ed.2d 831 (1980) (sentencing statutes enacted after offense could be applied to defendant without violating the ex post facto clause because they were ameliorative); State v. Bieg-enwald, 126 N.J. 1, 594 A.2d 172, 201-02 (1991) (because it does not meet the criteria for an ex post facto law as affirmed in Dobbert, judicial construction of aggravating circumstance can be applied retroactively to an offense antedating that construction); State v. McCoy, 327 N.C. 31, 394 S.E.2d 426, 432 n. 3 (1990) (changes in death penalty procedure in response to certain Supreme Court decisions are procedural and ameliorative and may be retroactively applied); Castro v. State, 749 P.2d 1146, 1150 (Okla.Crim. App.1987), cert, denied, 485 U.S. 971, 108 S.Ct. 1248, 99 L.Ed.2d 446 (1988) (judicial construction of statutory aggravating circumstance could be applied retroactively because defendant not subjected to change in quantum of punishment); Wallace v. State, 707 S.W.2d 928, 937-38 (Tex.App.1986), aff'd, 782 S.W.2d 854 (Tex.Crim.App.1989) (statutory change "involved the method of determination of appro*197priate punishment,” and, therefore, was procedural and could be retroactively applied); Smith v. Commonwealth, 219 Va. 455, 248 S.E.2d 135, 147 (1978), cert, denied, 441 U.S. 967, 99 S.Ct. 2419, 60 L.Ed.2d 1074 (1979) (no ex post facto violation because changes to death penalty statute were procedural and ameliorative).
. We note that the trial court determined that House Bill 91S2-1038 could not be applied to Thomas because it "is substantive in nature.” Yet, the trial court labelled the legislation as substantive after finding that it changed the punishment for first degree murder cases occurring during the hiatus period, thus relying on the definition of an ex post facto law as set forth in Calder.
. Additionally, we are not persuaded that, even if the change in the definition of the aggravator were detrimental to .Thomas, it would not survive the ex post facto test in Dobbert. Thomas argues that the change in the definition altered the prosecution’s burden of proving the aggravator but we fail to see how this affects the definition of a crime or the availability of a defense to a crime. While Thomas fails to specify how the alternative definition fits into the ex post facto test, we believe the most plausible argument is that, if the new definition is easier to prove, it is possible that a defendant might face a more burdensome punishment. However, we would also reject this argument because the aggravator itself is unchanged, and the alternative definition does not alter the penalty for first degree murder. An aggravating circumstance is not a separate penalty but a standard to guide the choice between alternative sentences of life imprisonment and death. Poland v. Arizona, 476 U.S. 147, 156, 106 S.Ct. 1749, 1755-56, 90 L.Ed.2d 123 (1986). Therefore, altering the definition of this standard has nothing "to do with the definition of crimes, defenses, or punishments, which is the concern of the Ex Post Facto Clause." Collins v. Youngblood, 497 U.S. 37, -, 110 S.Ct. 2715, 2724, 111 L.Ed.2d 30 (1990). Instead, as in Dobbert, 432 U.S. at 293-94, 97 S.Ct. at 2298-99, the application of the judicial definition instead of the statutory definition simply alters "the methods employed in determining whether the death penalty was to be imposed,” and would not affect retroactive application of this statute.
. Neither party to this case argues that a change in statutory aggravator (6)(g) rendered retroactive application of section 16-11-802 vio-lative of the ex post facto clauses, but the issue was raised by the defense in its brief in the companion case announced today, People v. Ashfield, 834 P.2d 236 (Colo.1992). Since in this opinion we dispose of the issue of the constitutionality of retroactive application of section 16-11-802, we address this change here. Section 16 — 11—103(6)(g), 8A C.R.S. (1986), read:
*202The defendant committed a class 1, 2 or 3 felony and, in the course of or in furtherance of such or immediate flight therefrom, he intentionally caused the death of a person other than one of the participants....
In 1987, this subsection was amended by the addition of the words "or attempted to commit” after "[t]he defendant committed." Act approved April 30, 1987, ch. 120, sec. 1, 1987 Colo.Sess.Laws 625. Section 16-ll-802(5)(g) reflects this 1987 change. We note therefore, that this statutory change occurred in 1987, was part of the pre-1988 law as well as the 1988 statute, and consequently was applicable and in effect at the time Thomas and the defendant in Ashfield allegedly committed these crimes. Since its inclusion in section 16-ll-802(5)(g) does not constitute a new change being retroactively applied, this amendment also fails to provide a basis for an argument that section 16 — 11— 802 violates the ex post facto clauses.