One issue is presented by this appeal: May a trial court validly sentence an individual to a term of one year or more in the state reformatory with the intention (at the time of sentencing) of bringing such individual two months thereafter before the court in order to modify the initial sentence, stay such sentence, and grant probation ?
The trial court’s original sentence here was invalid because it did not conform to the requirements of sec. 973.02, Stats. This section provides:
“973.02 Place of imprisonment when none expressed. When a statute authorizes imprisonment for its violation but does not prescribe the place of imprisonment, 1) a sentence of less than one year shall be to the county jail, 2) a sentence of more than one year shall be to the Wisconsin state pfisons and the minimum under the indeterminate sentence law shall be one year, and 3) a sentence of one year may be to either the Wisconsin state prisons or the county jail. But in any proper case sentence and commitment may nevertheless be to the Wisconsin home for women, the department or any house of correction or other institution as provided by law.”
While the trial court sentenced the defendant to several terms, both concurrent and consecutive, in the state prison (the Wisconsin State Reformatory), it did *579so with the then present intention that the defendant would serve no more than ninety days of the sentence in the Wisconsin state prisons. The trial court stated for the record during the hearing at which the sentence was amended (July 18, 1972), that it had intended to review that sentence within those ninety days. This was a circumvention of sec. 973.02, Stats. The legislature has not spelled out specific statutory authority for the procedure employed by the trial court, permitting the sentencing of a convicted defendant on a “trial-run” basis to the Wisconsin state prisons with the intention, not communicated at the time to the defense or the state, that the defendant would be ordered back for a sentence review within ninety days from the date of the original sentence.
Although, in entering its second and amended sentence in which the court reduced the underlying sentences from five to three years and then stayed the sentence and awarded probation, the trial court was reviewing the first sentence in the light of the information developed at the proceedings on July 18th; it, of course, was not acting with a view to correcting the original sentence which was considered invalid. The trial court obviously considered the first sentence valid and was merely reviewing it to determine whether some modification was warranted.
The new sentence is entirely valid. This court has previously approved a trial court’s action in entering a sentence that rectified a previous void sentence.1 In State ex reí. Copas v. Burke this court approved the subsequent action of a trial court in committing a sex offender to the sex deviate facility upon the revocation of the previously imposed probation. The trial court had previously imposed a punitive sentence even though *580specialized treatment had been recommended by the department.
This is precisely the situation in the present case and the new sentence in every respect is an effective correction of a previous invalid sentence.
The state contends that the trial court entered its amended sentence without a showing that the initial sentence was bottomed upon either a lack of pertinent information or misinformation. There is no such requirement at the present time as a jurisdictional prerequisite for the modification of a sentence by a trial court. The present rule as stated in Hayes v. State 2 is “that a trial court may exercise its inherent power to change and modify its judgments after the execution of the sentence has commenced and the term ended.” Although the time limit of ninety days within which a motion to modify a sentence was approved in Hayes, this time limit has been subsequently determined to be “regulatory” rather than “jurisdictional” thus permitting sentence modification in certain cases after the expiration of ninety days.3
While in Hayes this court did not delineate precise guidelines for exercise of the broad discretionary power of modifying a sentence, it did imply their existence:
“. . . Within reasonable limits we think an unjust sentence should be corrected by the trial court.” (Emphasis added.) 4
In Hayes this court further suggested the inherent power of the court to modify a previously imposed sentence “must be exercised within the limits of sound sentencing *581discretion.” 5 It was also held the reasons for such modification should be elaborated upon by the resen-tencing court. While both Hayes and Mattice v. State,6 also cited by appellant, involved the modification of sentences which had been imposed without the trial court’s knowledge of the defendants’ true criminal records, neither case mandates such misinformation or lack of information as a jurisdictional prerequisite to subsequent sentence reconsideration and modification.
The recent decision of this court in State ex rel. Warren v. County Court 7 does not support the state’s jurisdictional contention that the trial court has no authority to modify a previously imposed sentence unless the original sentence was based on misinformation or some lack of information.
While we have previously indicated that the trial court’s discretionary power to modify a previously imposed sentence is not unfettered, we deem it advisable to fashion guidelines for the guidance of trial courts in the performance of their discretionary functions of reviewing and modifying sentences. With this in mind, we adopt that portion of the American Bar Association’s Standards Relating to Sentencing Alternatives and Procedures, spelled out under sec. 6.1 (a) as follows:
“6.1 Authority to reduce: general.
“(a) It may be appropriate to authorize the sentencing court to reduce or modify a sentence within a specified time after its imposition or the final resolution of an appeal if new factors bearing on the sentence are made known. ...” 8
*582It is inappropriate for a sentencing court to make a change in an imposed sentence unless new factors are made known. The commentary to the ABA Standards 9 cites District Attorney for the Northern District v. Superior Court,10 which states:
“. . . Occasions inevitably will occur where a conscientious judge, after reflection or upon receipt of new probation reports or other information, will feel that he has been too harsh or has failed to give due weight to mitigating factors which properly he should have taken into account. In such cases the interests of justice and sound judicial administration will be served by permitting the trial judge to reduce the sentence within a reasonable time.”
We think the Massachusetts court goes too far. A trial court should not reduce a sentence on “reflection” alone or simply because it has thought the matter over and has second thoughts. It must base its modification on “new factors” brought to its attention.
Nothing said here varies the general rule that this court may review an allegedly excessive sentence or a sentence which is claimed to have been imposed in a manner indicating an abuse of discretion. However, in view of our statement “It is inappropriate for a sentencing court to make a change in an imposed sentence unless new factors are made known,” the requirement that a motion be made to the trial court to correct a sentence deemed excessive or imposed with an abuse of discretion 11 is unnecessary to preserve such question for review by this court unless new factors are, in fact, *583present which the trial court should consider as indicated herein.
By the Court. — Judgment affirmed.
State ex rel. Copas v. Burke (1965), 28 Wis. 2d 188, 136 N. W. 2d 778.
(1970), 46 Wis. 2d 93, 101, 175 N. W. 2d 625.
Lange v. State (1972), 54 Wis. 2d 569, 573, 196 N. W. 2d 680; State ex rel. Warren v. County Court (1972), 54 Wis. 2d 613, 617, 197 N. W. 2d 1.
Hayes v. State, supra, footnote 2, at page 105.
Id. at page 106.
(1971), 50 Wis. 2d 380, 184 N. W. 2d 94.
Supra, footnote 3.
American Bar Association, Standards Relating to Sentencing Alternatives and Procedures, Part VI, sec. 6.1 (approved draft, 1968).
American Bar Association, Standards Relating to Sentencing Alternatives and Procedures (tentative draft, 1967), Commentary, Part VI, sec. 6.1, pp. 278, 279.
(1961), 342 Mass. 119, 128, 172 N. E. 2d 245.
Tatum v. State (1971), 51 Wis. 2d 554, 556, 187 N. W. 2d 137; Farley v. State (1971), 50 Wis. 2d 113, 115, 183 N. W. 2d 33.