concurring and dissenting, with whom GOLDEN, Justice, joins.
I agree that this case must be reversed and remanded for resentencing. In deciding to reduce the maximum term by twice the pre-trial confinement time, the sentencing judge clearly went overboard. It might even be said that he walked the plank. Consequently, I must agree that resentenc-ing in accordance with law is appropriate.
I cannot join in the holding or rationale of the majority with respect to the credit for pre-trial incarceration against the minimum sentence. In this instance, the statute clearly provides for a minimum term of imprisonment of not less than ten years. In the light of both the legislative mandate set forth in § 7-13-201, W.S.1977, and the prior pertinent holdings of this court in Cook v. State, 710 P.2d 824 (Wyo.1985), and Williams v. State, 692 P.2d 233 (Wyo.1984), I am convinced that the trial court correctly concluded it had no authority to reduce the minimum term below ten years.1 In Williams and Cook, this court held that a sentencing court cannot assess punishment below a mandated minimum term. The reliance by the majority upon Harley v. State, 737 P.2d 750 (Wyo.1987), and Heier v. State, 727 P.2d 707 (Wyo.1986), to establish the discretionary authority of the trial court to do so is misplaced. In neither instance did the statute prescribe a mandatory minimum term. Consequently, the controlling authority is Williams.
In its present form, § 7-13-201 perhaps makes the situation a bit awkward because the maximum term must be eleven years, one month, and ten days when the minimum term is ten years. In this instance, in order then to credit pre-trial confinement against the maximum term, which I agree the court was required to do, the maximum term had to be at least twelve years, five months, and twenty days. In my judgment, that becomes, by operation of § 7-13-201 and the requirement that Jones receive credit on his maximum sentence for pre-trial incarceration, the minimum maximum term which the court lawfully could impose.
Any other result infringes upon the constitutional prerogatives of both the legislative department and the executive department of state government. There can be *374no question that the power to prescribe punishment is the prerogative of the legislative department. E.g., Baum v. State, 745 P.2d 877 (Wyo.1987); Williams, 692 P.2d 233; Evans v. State, 655 P.2d 1214 (Wyo.1982); and Chavez v. State, 604 P.2d 1341 (Wyo.1979), cert. denied 446 U.S. 984, 100 S.Ct. 2967, 64 L.Ed.2d 841 (1980). The imposition of a minimum sentence less than the mandatory minimum term established by the legislature is a clear violation of the separation of powers doctrine.
The question of what sentence appropriately may be imposed is an entirely different one from a determination of how much of that sentence has been served. Because the authority of the sentencing court is circumscribed with respect to a mandatory minimum term prescribed by the legislature, any effort by the sentencing court to determine how much of that term may already have been served infringes upon the prerogative of the executive department of state government. The majority, I believe adequately, justifies the authority of the executive department to determine the fact of whether a sentence has been served. If the question before us were whether the executive department failed to credit time already served on a sentence, I might well agree that the pre-trial confinement must be so credited. My position is that the sentencing court cannot do that.
Consequently, while I agree that this case must be reversed and remanded for sentencing, I am clear that the sentencing court cannot impose a minimum term of less than ten years, and the maximum term to be imposed must, in this instance, be at least twelve years, five months, and twenty days. Appropriate credit for pre-trial confinement of one year, four months, and ten days then can be incorporated in the court sentence without the ten year minimum sentence being greater than ninety percent of the maximum sentence. The determination of how much of the sentence has been served would be the prerogative of the executive department.
. In the case of Williams v. State, 692 P.2d 233 (Wyo.1984), the district court, mistakenly in my view, did enter a Judgment and Sentence of the Court which provided that credit should be given for time served against both the minimum and maximum sentences. The State has no appeal in such an instance, and that fact does not serve to dilute the holding that the sentencing court cannot assess punishment below a mandatory minimum term. In Cook v. State, 710 P.2d 824 (Wyo.1985), the district court entered a Judgment and Sentence which provided that the defendant was "to serve a term of not less than five (5) years nor more than five and one-half (5 ½) years on each count with credit for 168 days already served in the Natrona County Jail, * * The file discloses that the executive department, through the staff of the Wyoming State Penitentiary, interpreted that Judgment and Sentence to the end that credit of 168 days was given off the maximum sentence only, and his minimum release date was computed to end at the expiration of the full five years of the minimum sentence. This construction of the Judgment and Sentence was communicated to the sentencing judge who apparently was satisfied with the interpretation by the penitentiary staff. The net result in Cook is not consistent with a conclusion that the sentencing court gave credit for pre-trial confinement against both the maximum and minimum sentence.