OPINION ON REHEARING
BUSSEY, Judge:Upon petition for rehearing, the appellants in part contend that this Court erred in the decision previously rendered herein on September 17, 1975, regarding the constitutionality of 21 O.S.Supp.1974, §§ 701.5 *592and 701.6.1 Appellants assert that by failing- to ascertain and give effect to the intention of the Legislature as clearly expressed in those statutes our interpretation defeated the Legislative intent and was not in accord with fundamental rules of statutory construction. Conceiving our holding to have turned upon those statutes being fatally vague and uncertain regarding the conduct of the evidentiary hearing contemplated therein, the appellants argue that procedural implementation of that hearing could readily be accomplished within the rule making authority of this Court. This interpretation misconstrues the basis for our decision regarding the constitutionality of those statutes but justifiably demonstrates the need for clarification of that aspect of our prior opinion.
Unlike many other states which sought to retain some discretion in the sentencing process,2 the Oklahoma Legislature pursued the extreme approach necessary to curb the unbridled discretion condemned in Furman,3 and eliminated that discretion for the crime of first degree murder by making the death penalty mandatory upon conviction for that offense. The Legislature desired to employ a scheme of capital punishment in the enforcement of First Degree Murder but was undoubtedly and understandably in a quandary as to how to comply with Furman. Rather than attempting to establish standards or guidelines for the imposition of the death penalty under the very uncertain requirements of Furman, the Legislature adopted this approach in a diligent effort to assure compliance with that decision. Our statutes upon appellate review purport to confer upon this Court the authority to modify a death sentence to life imprisonment when that sentence is discriminatory or disproportionate. The decision in Furman turned upon discriminatory and disproportionate imposition of the death penalty under mercy statutes then in existence. Our statutes upon appellate review were therefore aimed directly at the crux of that decision. Even in other states retaining some discretion in the sentencing procedure, quite similar provisions upon appellate review have been adopted in an effort to comply with Furman. See, Coley, and People ex rel. Rice, infra. We are therefore persuaded that the Oklahoma Legislature adopted these statutes upon appellate review of the death sentence in an effort to insulate or protect an otherwise mandatory scheme of capital punishment against any deficiencies that might enter the system and result in further constitutional *593challenge, and did not intend that these statutes should operate as mercy provisions. If the intent of the Legislature had been otherwise, we are persuaded that they would have prescribed specific conditions to be considered just as other states which have endeavored to retain controlled discretion, rather than adopting these general provisions couched in terms of the ultimate evil at which Furman was directed. However, we are of the further opinion that in this endeavor the Legislature misconceived the propriety and necessity of appellate modification upon such criteria under a mandatory scheme of capital punishment.
As the Legislature resolved to otherwise mandate but one punishment for first degree murder, appellate modification upon the vague and indefinite criteria that “the sentence of death ... is substantially disproportionate to the penalty imposed in similar cases, considering both the crime and the defendant,” would be tantamount to this Court exercising the unguided sentencing discretion previously extended to the jury or trial court under the mercy statutes condemned in Furman. See, People ex rel. Rice, infra. Any attempt by this Court to delineate Legislative intent from this uncertain criteria would be equivalent to substantive legislation and not within our rule making authority. Under this criteria we are left hopelessly in doubt as to the meaning of “similar cases.” To illustrate, we are first left to speculate upon whether that phrase encompasses only murder convictions or extends so far as to include all homicide cases which might have resulted in murder convictions, and whether this language embraces only cases appealed to this Court or all cases prosecuted in the trial courts below. Further, we could not draw a comparison to cases preceding Furman under our prior mercy statute since the punishment in those cases was imposed under the same discretionary sentencing statute held unconstitutional by Furman. Such a comparison would simply perpetuate the very discrimination found to exist in that decision. Reference to only those cases wherein this Court previously affirmed the murder conviction but modified the death sentence to life imprisonment would have the same effect since we there exercised that authority in light of the disposition of other cases prosecuted under the mercy statute. We certainly could make no comparison to cases subsequent to Furman but prior to the enactment of our present statute since life imprisonment was then the only punishment for murder. With the enactment of our current legislation, the death penalty is now otherwise mandatory for selected categories of homicide. Insofar as cases arising under a comparable scheme of enforcement, we are therefore without “similar cases” upon which to base a valid comparison. Although quite similar provisions upon appellate review were upheld in Coley v. State, 231 Ga. 829, 204 S.E.2d 612 (1974), and seemingly held valid in People ex rel. Rice, infra, these cases are distinguishable since the legislation involved therein retained such discretion in the sentencing process that there would arguably be similar cases upon which to formulate a comparison.
Moreover, any attempt by this Court to delineate standards or guidelines under the foregoing criteria would be inconsistent with what we deem to have been the actual purpose of the Legislature in enacting these provisions. Since we have concluded that these statutes were adopted as insulating or protective measures for an otherwise mandatory scheme of capital punishment and were not intended to operate as mercy provisions, disproportionate sentencing not caused by discrimination would only occur when the evidence was insufficient to sustain the verdict. As there is now but one penalty for first degree murder in this State, the appropriate inquiry for this Court is whether a conviction in such cases is consistent with the law. Where the evidence is insufficient to sustain a conviction for first degree murder but clearly sufficient to otherwise support a conviction upon a lesser included of*594fense, modification of the judgment to the statutory range of punishment for the included offense would be an appropriate consideration under the more general authority conferred upon this Court by the provisions of 22 O.S.1971, § 1066. In such a case the necessity for modification is presented as a matter of law rather than as a mere discretionary determination by this Court. As previously observed, this Court is otherwise without authority to modify a sentence below the minimum punishment established by the statutory provisions governing the particular crime involved. See, Griffith v. State, Okl.Cr., 516 P.2d 1348 (1973), and Meeks v. State, Okl.Cr., 501 P.2d 887 (1972). Also, modification by this Court must be the exercise of a judicial power as an award of justice, as distinguished from the executive power of clemency vested in the governor to commute, reprieve, pardon or parole, as an award of grace. See, Parish v. State, 77 Okl.Cr. 436, 142 P.2d 642 (1943), and Harvell v. State, 97 Okl.Cr. 97, 258 P.2d 702 (1953).
Discriminatory application of the death sentence is the only other basis for modification under these statutes. We are of the opinion that a new trial is the necessary and proper remedy in such cases insofar as any discrimination may be thereby remedied. Discrimination arising during the trial of a case could only result in the trier of fact failing to deliberate impartially upon the defendant’s guilt of first degree murder or refusing to give due consideration to a lesser included offense since assessment of the death penalty is otherwise mandatory. In either case reversal for a new trial rather than modification would be necessary to preserve the defendant’s right to a fair and impartial trial. Additionally, when such discrimination may be remedied by reversal for further prosecution, modification of the death sentence as a remedy would operate to introduce discrimination of the nature condemned in Furman against others lawfully convicted of first degree murder since capital punishment is otherwise mandatory for that offense in this State. If in any particular case an accused is discriminatorily charged with first degree murder, a different situation would be presented since reversal for further prosecution on that charge would not operate as a remedy, however, neither might modification to life imprisonment cure the error depending upon the nature of the discrimination. Since such a case would have to be resolved upon the basis of the particular facts presented, we are of the opinion that further discussion thereof should be deferred to an appropriate case.
In view of the foregoing considerations and because the evidentiary hearing contemplated by these statutes before this Court is duplicitous to established procedure for the presentation of evidence before the trial court upon any legal issue, we are of the opinion that such a hearing would be a vain and needless task which we cannot presume the Legislature to have intended. For the foregoing reasons and to the extent herein discussed, we are therefore of the opinion that these statutes are unconstitutional.
Appellants also contend that the severa-bility clause enacted along with the bill adopting 21 O.S.Supp.1974, § 701.1 et seq.,4 cannot be invoked to sever the unconstitutional provisions of §§ 701.5 and 701.6 from the remaining portions of that enactment since we cannot presume that the Legislature would have passed that bill without fully incorporating the provisions now held to be unconstitutional.
This proposition presents primarily a question of Legislative intent. In the second and third paragraphs of the Syllabus to Englebrecht v. Day, 201 Okl. 585, 208 P.2d 538 (1949), the following appears:
“The unconstitutionality of a portion of an Act of the Legislature does not defeat or affect the validity of the remain*595ing provisions unless it is evident that the Legislature would not have enacted the valid provisions with the invalid provisions removed, if with the invalid provisions removed the rest of the Act is plain and fully operative as law.
“The effect of a provision in an Act of the Legislature that the invalidity of any sentence, clause or provision in the Act shall not affect the remaining portions, is to create a presumption that, omitting the unconstitutional portions, the remaining portions would have been enacted by the Legislature.”
Also see, State ex rel. Roth v. Waterfield, 167 Okl. 209, 29 P.2d 24 (1934), and Sterling Refining Co. v. Walker, 165 Okl. 45, 25 P.2d 312 (1933).
In support of this proposition the appellants cite People ex rel. Rice v. Cunningham, Ill., 336 N.E.2d 1 (1975). Following conviction for murder but prior to sentencing, the statute there under consideration directed that a three judge court be convened for the purpose of hearing evidence and determining whether that crime was committed under circumstances enumerated in the statute. If a majority of that court determined such circumstances to have existed, then the accused was to be sentenced to death unless a majority of the judges also found that there were “compelling reasons for mercy.” The court there held the mercy clause to contain inadequate standards or guidelines, and further held the legislative creation of this three judge court and another provision directing an appeal of capital cases to an intermediate appellate court to be violative of specific State constitutional provisions. In so holding the court concluded:
“In summary, we hold invalid the provision of the death penalty statute pertaining to the impaneling of a three-judge court, the provision relating to the exercise of ‘compelling reasons for mercy’ which would obviate the imposition of the death penalty and the provision establishing the appellate review procedure for one sentenced to death. The provisions that we have held unconstitutional are so connected and dependent upon one another as to warrant the belief that the • legislature would not have passed the remaining portions of the statute independent of these. Consequently, the invalid sections may not be severed. The imposition of the death penalty under this statute is improper, ...”
We are of the opinion that case is readily distinguishable, however, since the intent of the Legislature could obviously not be implemented with the invalid provisions removed. In response to Furman, the Illinois Legislature clearly endeavored to retain discretion in the sentencing process and did not intend to adopt a mandatory scheme of capital punishment. The Legislature there intended that only those within the statutory categories and not within the purview of the mercy-clause suffer death, and that these determinations be made by a majority of a three judge court specially convened after conviction but before sentencing. A procedure for appellate review of the death sentence quite similar to our own was established since discretion would be exercised in every case under the mercy clause. The invalidity of the mercy clause and the unconstitutionally conceived three judge court prohibited implementation of that sentencing procedure so as to effectuate legislative intent.
In contrast, the Oklahoma Legislature adopted a mandatory scheme of capital punishment and eliminated discretion in the sentencing procedure for the crime of first degree murder. Similar provisions upon appellate review of the death penalty were adopted as a protective measure against further constitutional attack upon an otherwise mandatory scheme of enforcement and were not intended to operate as mercy provisions. We would therefore frustrate the intent of the Legislature by holding the invalid aspects of these insulating provisions inseparable from the remaining provisions. Additionally, the contention of the appellants fails to give appropriate significance to the intention of the Legislature as embodied in the accom*596panying severability clause, and the presumption arising therefrom that the Legislature would have enacted the valid provisions omitting the unconstitutional aspects of the other provisions. The conclusion is not evident that the Legislature would have refused to enact the valid provisions with the unconstitutional aspects of the other provisions removed, and the Act is otherwise fully operative. We are therefore of the opinion that this proposition is without merit.
Appellants further contend that our holding with respect to appellate review and modification of the death sentence under 21 O.S.Supp.1974, §§ 701.5 an 701.6, so alters the consequences of conviction for a capital offense to their disadvantage that constitutional provisions against ex post facto laws 5 require prospective application of the death penalty only.6 While conceding that the rationale for constitutional ex post facto provisions has been read into the due process clause as a limitation upon the effect of judicial construction, see Bouie v. Columbia, 378 U.S. 347, 84 S.Ct. 1697, 12 L.Ed.2d 894 (1964), the State points out that constitutional prohibitions against ex post facto law operate directly only as a restraint upon legislative powers.7
In the early decision of Calder v. Bull, 3 Dall. 386, 1 L.Ed. 648, 650 (1798), the United States Supreme Court first defined ex post facto laws as follows:
“ . . . 1st. Every law that makes an action done before the passing of the law; and which was innocent when done, criminal; and punishes such action. 2d. Every law that aggravates a crime, or makes it greater than it was, when committed. 3rd. Every law that changes the punishment, and inflicts a greater punishment, than the law annexed to the crime, when committed. 4th. Every law that alters the legal rules of evidence, and receives less, or different, testimony, than the law required at the time of the commission of the offense, in order to convict the offender. . . .”
Generally, an ex post facto law has been defined as any law passed after the commission of an offense, which in relation to the offense or its consequences, alters the situation of an accused to his disadvantage. See: Kring v. Missouri, 107 U.S. 221, 2 S.Ct. 443, 27 L.Ed. 506 (1883); In re Medley, 134 U.S. 160, 10 S.Ct. 384, 33 L.Ed. 835 (1890), and, Rooney v. North Dakota, 196 U.S. 319, 25 S.Ct. 264, 49 L.Ed. 494 (1905).
Our statutory scheme of capital punishment was enacted and fully effective prior to the commission of the instant offense. These provisions clearly define the subject offense to constitute first degree murder and made the imposition of the death penalty mandatory upon conviction. The statutes upon appellate review of the death sentence purported to confer modification authority upon this Court only to the extent that the death sentence was discriminatory or substantially disproportionate. Clearly, our decision upon the constitutionality of those provisions did not increase the severity of the punishment for first degree murder since the death penalty was mandatory unless modification was necessary as therein contemplated. Furthermore, unless the death penalty in any particular case was the result of discrimination or substantially disproportionate, an accused convicted of first degree murder *597could not seek modification under those provisions since they did not otherwise purport to confer such power upon this Court.
There is a total absence of any indication whatsoever that the death penalty was discriminatory in this case and under the facts and circumstances presented that sentence was in no sense disproportionate. The evidence was clearly sufficient to support the conclusion of the jury that while acting in concert the appellants killed Cherry Lee Kennedy with premeditation during the commission of an armed robbery. The record further indicates that the crime was perpetrated unmasked late at night while the victim was alone, and she was brutally shot and killed despite her lack of resistance to the robbery. In view of the verdict of the jury, we are therefore persuaded from our examination of the record that the victim was killed incident to a previously conceived plan to eliminate her as a witness to the robbery. The value the appellants placed upon the life of Ms. Kennedy is illustrated by reference to the fact that the robbery grossed them about $32.00 and two cartons of cigarettes and necessitated the disposal of a gun costing $30.00. Appellant Williams admitted prior felony convictions for embezzlement and a federal auto theft violation, and appellant Justice admitted prior felony convictions for second degree forgery and attempted auto larceny. Further, in Justus v. State, Okl.Cr., 542 P.2d 598 (1975), this Court recently affirmed the conviction of appellant Justus for first degree murder committed three weeks prior to the instant offense while perpetrating another armed robbery. Therefore, if the scheme of capital punishment adopted by the Oklahoma Legislature is to have any efficacy the death penalty cannot in any manner be here considered disproportionate, irrespective of our present decision regarding the provisions upon appellate review. However, we are fortified by our conclusion that the Legislature did not intend for these statutes to act as mercy provisions but rather adopted them as protective measures to insulate an otherwise mandatory scheme of capital punishment against further constitutional challenge under Furman.
Since the appellants are clearly not among the class of persons within the purported ambit of the provisions upon appellate review, this Court would not have had the authority to modify the death sentences in this case had those statutes been fully valid. Consequently, our interpretation of those provisions and decision upon their constitutionality did not restrict the possible range of punishment applicable to the appellants. Nor did our holding thereupon alter the situation of the appellants to their disadvantage in relation to the offense or its consequences. The cases cited by appellants are upon this basis clearly distinguishable. We therefore conclude that our decision herein upon the provisions for appellate review of the death sentence did not operate as an ex post facto law against the appellants nor deny them due process of law, and hold this proposition to be without merit.
In this regard appellant Justus also argues that our decision upon the appellate review provisions deprived him of an opportunity to establish that the death sentence was discriminatory or disproportionate. Subsequent to the issuance of our interim opinion herein, the evidentiary hearing contemplated by these statutes was set for hearing with notice of nearly one month. Not until the day prior to that hearing did appellant Justus present this Court with a motion that we establish guidelines for the review of death sentences under those provisions, and appellant Williams filed an identical motion the day of that hearing. The appellants then argued those motions at that hearing but the purpose of the hearing was frustrated since no evidence whatsoever was presented. Neither did the appellants endeavor to establish that the death sentences were discriminatory or disproportionate when the present petitions for rehearing were heard by this Court. Our prior decision express*598ly did not limit the right of the appellants to present a motion for new trial based upon newly discovered evidence nor preclude appellants from seeking any appropriate post conviction relief. We are therefore of the opinion that this contention is untenable. Other propositions raised by appellant Justus were first presented in his original brief and fully considered in our previous decision.
For the above and foregoing reasons, the decision previously rendered herein is reaffirmed, the order of this Court staying execution of sentence pending appeal is set aside, and the Clerk of this Court is therefore directed to issue mandate forthwith.
The date originally appointed for the execution of the appellants having passed pending this appeal, it is further ordered, adjudged and decreed that each judgment and sentence appealed from be carried out by the electrocution of the appellants, Bobby Joe Williams and Allen Clayburn Jus-tus, by the Warden of the State Penitentiary at McAlester, Oklahoma, on Monday, February 23, 1976.
BRETT, P. J., and BLISS, J., concur.
. Title 21 O.S.Supp.1974, §§ 701.5 and 701.6, respectively, are as follows:
“The Court of Criminal Appeals when reviewing a judgment and sentence of death shall, in the first instance, determine whether errors of law occurring at trial require reversal or modification, but if the Court shall determine that there are no errors of law in the record requiring reversal or modification, the Court shall then convene for the purpose of reviewing the sentence of death. The Court shall set a date certain for an evidentiary hearing, the purpose of which will be to determine if the sentence of death comports with the principles of due process and equal protection of the law. Upon the hearing the Court shall determine whether the sentence of death was a result of discrimination based on race, creed, economic condition, social position, class or sex of the defendant or any other arbitrary fact; and the Court shall specifically determine whether the sentence of death is substantially disproportionate to the penalty imposed in similar cases, considering both the crime and the defendant.” “Should the Court determine that the sentence of death is discriminatory or is substantially disproportionate to the penalty imposed in similar cases, considering both the crime and the defendant, the Court shall modify the sentence of death to life in the penitentiary at hard labor.”
. See: Comment, Discretion and the Constitutionality of the New Death Penalty Statutes, 87 Harv.L.Rev. 1690 (1974); State v. Dixon, Fla., 283 So.2d 1 (1973); Jurek v. State, 522 S.W.2d 934 (Tex.Cr.App.1975); Coley, infra; and, People ex rel. Rice, infra.
. See, consolidated cases of Furman v. Georgia, Jackson v. Georgia, and Branch v. Texas, 408 U.S. 238, 92 S.Ct. 2726, 33 L.Ed.2d 346 (1972), hereinafter cited by reference to the lead case.
. See, H.B. No. 1101, Okl.Sess.Laws 1973, Ch. 167.
. See, U.S.Const., art. I, § 10, cl. 1, and Okla.Const., art. II, § 15.
. Appellants cite in support of this proposition: Kring v. Missouri, infra; Thompson v. Utah, 170 U.S. 343, 18 S.Ct. 620, 42 L.Ed. 1061 (1898); Lindsey v. Washington, 301 U.S. 397, 57 S.Ct. 797, 81 L.Ed. 1182 (1937); Bouie v. Columbia, infra; State v. Dickerson, Del.Supr., 298 A.2d 761 (1972); and, State v. Waddell, 282 N.C. 431, 194 S.E.2d 19 (1973).
. See: Ross v. Oregon, 227 U.S. 150, 33 S.Ct. 220, 57 L.Ed. 458 (1913); Frank v. Mangum, 237 U.S. 309, 35 S.Ct. 582, 59 L.Ed. 969 (1915); and, United States v. Rundle, 383 F.2d 421 (3rd Cir. 1967), cert. denied 393 U.S. 863, 89 S.Ct. 144, 21 L.Ed.2d 131.