This case raises two important issues: (1) whether appeal or mandamus is the proper remedy when the government alleges that the district court has acted beyond the scope of its lawful authority in reducing the sentence of a convicted criminal defendant; and (2) whether the district court may reduce a defendant’s sentence under Rule 35(a) of the Federal Rules of Criminal Procedure when the original sentence was based on an erroneous prediction concerning the amount of time the defendant would likely serve in prison prior to parole. After reviewing our prior decisions, we conclude that (1) mandamus, not appeal, is the government’s proper remedy, and (2) the district court lacked the authority to enter the order reducing the defendant’s sentence under Rule 35(a). *
A. The Facts
The facts are largely undisputed. Roscoe Dean, a former Georgia state senator, was tried and convicted in the United States District Court for the Southern District of Georgia on three counts of conspiracy to import cocaine, marijuana, and methaqualone, in violation of 21 U.S.C. §§ 956,
*538
963.
1
In June, 1980, Dean was sentenced to concurrent five-year prison terms and fined $10,000 for each offense. On appeal, the former Fifth Circuit ruled that the evidence at trial showed the existence of only one conspiracy, not three, and remanded the case to the district court with instructions to vacate two of the three convictions and to resentence Dean.
United States v. Dean,
On September 15, 1982, Dean filed a motion for reduction of sentence under Rule 35(b) of the Federal Rules of Criminal Procedure. 3 On October 22, the district court denied the motion. On November 1, Dean moved for reconsideration; two weeks later, that motion likewise was denied.
On February 1,1984, Dean filed a motion to correct an illegal sentence pursuant to Rule 35(a). 4 In his motion, Dean alleged that the sentencing court had relied on an erroneous prediction by a probation officer concerning the length of time Dean would likely serve in prison prior to parole. The probation officer had predicted that, under the Parole Commission’s guidelines, and assuming the imposition of a sentence of not more than nine years’ imprisonment, Dean would likely serve between 24 and 36 months prior to parole. On July 14, 1983, however, the Parole Commission determined that Dean would not become eligible for parole until he had served 40 to 52 months of his five-year sentence. 5 On January 17, 1984, after an exchаnge of letters between Dean, the district court, and the Parole Commission, the Commission affirmed its prior decision as to Dean’s parole eligibility.
On April 5,1984, the district court granted Dean’s motion, “modified” Dean’s sentence “to be limited to time already served by the defendant,” and ordered Dean released from prison instanter, 6 *539 The government filed a notice of appeal 7 and a petition for a writ of mandamus 8 on the grounds that the district court lacked the authority to reduce Dean’s sentence. On June 27, a panel of this court denied without opinion the government’s petition for a writ of mandamus. In re United States, No. 84-8475 (11th Cir. June 27, 1984) (unpublished order). Shortly thereafter, Dean filed a motion to dismiss the government’s appeal for lack of jurisdiction. The government’s memorandum in opposition to Dean’s motion suggested that, in the event the court granted the motion to dismiss the appeal, the court should “reinstate” the government’s petition for a writ of mandamus. The government subsequently filed motions to (1) consolidate the appeal with the previous mandamus action, (2) vacate the order denying the petition for a writ of mandamus, and (3) refile the petition for a writ of mandamus.
B. The Motion to Dismiss the Government’s Appeal
In the motion to dismiss the government’s appeal, Dean contends that this court lacks jurisdiction to hear the appeal because no statute permits the government to appeal a sentence modifiсation order entered in a Rule 35 proceeding. The government, on the other hand, contends that the district court’s order is appealable as a “final decision” under 28 U.S.C. § 1291. 9
This issue is controlled by the former Fifth Circuit decision in
United States v. Denson,
The former Fifth Circuit dismissed the government’s appeal for lack of jurisdiction. The cоurt first noted the long-established rule that the government cannot appeal in a criminal ease without the express
*540
authorization of Congress.
Denson,
[CJertain orders relating to a criminal case may be found to possess sufficient independence from the main course of the prosecution to warrant treatment as plenary orders, and thus be appealable on the authority of 28 U.S.C. § 1291 ... just as in civil litigation orders of equivalent distinctness are appealable on the same authority____
Id.
at 1126 (quoting
Carroll v. United States,
The order appealed from must be severable from, and collateral to, the main case; the right involved must be so important that to deny review would be inappropriate; the issue presented must be such that postponing review until the final termination of the case would cause the irreparable loss of the valued right.
Id. (citation omitted). Applying these factors to the case before it, the court concluded that “[t]he sentencing process is the inevitable culmination of a successful prosecution; it is an integral aspect of a conviction.” Id. (emphasis added). The court thus held that “the orders of sentence and probation are not possessed of ‘sufficient independence’ from the criminal case to permit a Government appeal under 28 U.S.C. § 1291,” id. (citations omitted), and dismissed the government’s appeal. 12
The order in the instant case, like the one in
Denson,
fails to qualify as. a “final order” under 28 U.S.C. § 1291 because it is not “possessed of ‘sufficient independence’ ” from the underlying criminal case. The government attempts to distinguish
Denson
on the grounds that
Denson
involved an appeal of the district court’s original sentencing order, whereas here the government seeks to appeal an order modifying Dean’s original sentence. We do not find this distinction significant. Under
Denson,
the entire “sentencing process” is “an integral aspect of a conviction.”
*541 C. The Effect of the Prior Denial of the Government’s Petition for a Writ of Mandamus
We will treat the government’s three pending motions as a new petition for a writ of mandamus. Because another panel of this court previously denied an identical petition filed by the government, In re United States, No. 84-8475 (11th Cir. June 27, 1984) (unpublishеd order), we must decide whether the doctrines of res judicata or law of the case preclude us from reaching the merits of the new petition.
In general, a prior decision will have
res judicata
effect only if it was a decision “on the merits.”
Lawlor v. National Screen Service Corp.,
As to ... more limited uses of extraordinary writs, on the other hand, preclusion ordinarily is inappropriate if the first decision was governed by curtailed procedures, discretionary grounds of decision, or special limits____
... Denial of a writ commonly rests on severe limitations of jurisdiction and discretion that prevent the court from аpplying ordinary tests of reversible error. If a decision is confined by these limitations, it should not preclude examination of the merits in later proceedings. Preclusion is appropriate only if denial rested on the merits of the questions presented rather than remedial limitations.
18 C. Wright, A. Miller & E. Cooper,
supra,
§ 4445 at pp. 393-94, 396-97 (footnotes omitted);
see Heinemann Chemical Co. v. Heiner,
Here, the prior denial of the government’s petition was announced in a one-line, unpublished order.
In re United States,
No. 84-8475 (11th Cir. June 27, 1984) (unpublished order). The order does
*542
not provide us with a basis for determining the grounds on which the panel denied the petition. In this situation, we find persuasive the conclusion reached by the D.C. Circuit in
United States v. Hubbard,
Nevertheless, because of the writ’s extraordinary nature, this court’s earlier denial, without statement of reasons, of the Church’s petition for mandamus ... has no bearing on our decision of these appeals.
Hubbard,
Similarly, the law of the case doctrine does not prevent us from reaching the merits of the new petition. Although one aspect of the doctrine is that an appellate panel generally defers to a prior ruling in the same case by another panel of the same court,
see United States v. Burns,
Here, the government’s previous petition for a writ of mandamus was summarily denied, perhaps on the grounds that the government’s appeal was still pending rather than on the merits.
See United States v. Denson,
Dean contends that the government is guilty of laches because it did not attempt to contest the denial of the prior petition until November 5, 1984, more than four months after the entry of the order denying the petition. The government’s *543 explanation for this delay, however, is reasonable: Knowing that its appeal was still pending, the government justifiably assumed that the panel had denied the petition for a writ of mandamus on the grounds that appeal, not mandamus, was the proper remedy.
The instant case is distinguishable from
United States v. Olds,
This case is more closely analogous to the recent Third Circuit decision in
United States v. Ferri,
[Fjrom the outset, [the defendant] was put on notice that the government was challenging the reduction of his sentence. After filing its appeal, the government, being justifiably uncertain as to the proper procedural vehicle for review of an order reducing a criminal sentence, filed its petition for a writ of mandamus____ Thus, in view of the fact that in this case the government expeditiously appealed the order in question, we reject [the defendant’s] contention that the government is guilty of laches with respect to its filing of the mandamus petition.
Id. at 153 (citation omitted).
We agree with the views expressed by the Third Circuit in Ferri, and we cannot say that the government acted unreasonably in the instant case. We therefore hold that the government was not guilty of laches in contesting the denial of the prior petition for a writ of mandamus.
D. The New Petition for a Writ of Mandamus
Finally, we address the merits of the new petition for a writ of mandamus. The government contends that the writ should issue because the district court lacked the authority under Rule 35 to reduce Dean’s sentence and because mandamus is the proper remedy. Dean responds that the district court had the authority to “correct” the sentence under Rule 35(a) because the sentence was originally entered on the basis of an erroneous material assumption about the length of time he would likely serve in prison prior to parole. Dean contends that, in view of this erroneous assumption, his original sentence violated the due process clause.
Rule 35(a) provides that “[t]he court may correct an illegal sentence at any timе.” Fed.R.Crim.P. 35(a). The Supreme Court’s decision in
United States v. Addonizio,
*544 The decision as to when a lawfully sentenced defendant shall actually be released has been committed by Congress, with certain limitations, to the discretion of the Parole Commission. Whether wisely or not, Congress has decided that the Commission is in the best position to determine when release is appropriate, and in doing so, to moderate the disparities in the sentencing practices of individual judges____
The import of this statutory scheme is clear: the judge has no enforceable expectations with respect to the actual release of a sentenced defendant short of his statutory term. The judge may well have expectations as to when release is likely. But the actual decision is not his to make, either at the time of sentencing or later if his expectations are not met____ [W]e hold that subsequent actions taken by the Parole Commission — whether or not such actions accord with a trial judge’s expectations at the time of sentencing — do not retroactively affect the validity of the final judgment itself.
Id.
at 188-90,
The Court’s message in Addonizio could not have been stated more clearly. A sentence is not “illegal” simply because the original sentencing judge mistakenly believed that the Parole Commission would release the defendant before the end of the defendant’s full sentence. Whether the sentencing judge’s belief was based on the judge’s own knowledge of the parole system or on a prediction contained in the presentence report is irrelevant. The authority to determine whether a defendant will be released on parole is vested in the Parole Commission, not the sentencing judge. The sentencing judge may not use Rule 35(a) as a means to usurp the authority of the Parole Commission. 18
Dean argues that
Addonizio
involvеd a claim that the sentence was merely “illegal,” whereas the instant case involves an alleged violation of due process. We are unpersuaded by this imaginative attempt to distinguish
Addonizio.
A sentence that, under
Addonizio,
is not “illegal” can hardly rise to the level of a due process violation. Moreover, in
Addonizio
the Supreme Court concluded that the sentencing court’s erroneous assumption about the defendant’s parole eligibility did not constitute “misinformation of constitutional magnitude”; the Court stated that “the proceeding was not infected with any error of fact or law of the ‘fundamental’ character that renders the entire proceeding irregular and invаlid.”
Id.
at 186,
The due process cases relied upon by Dean are completely inapposite. Those cases do indeed stand for the proposition that a sentencing court cannot rely on “false assumptions” without violating the due process clause.
See United States v. Tucker,
Because the district court lacked the authority to reduce Dean’s sentence under Rule 35(a), we conclude that Dean’s new sentence is unlawful. Our final inquiry concerns whether mandamus is the government’s proper remedy. It is axiomatic that mandamus is an “extraordinary remedy for extraordinary causеs,”
United States v. Denson,
Absent the availability of mandamus, the limitation imposed by congress on the sentencing latitude accorded the trial court would go unheeded. The assumption of broad discretion by an appellate court in deciding whether or not to issue mandamus would be almost equivalent to granting the trial court the statutory authority denied it by congrеss. While relatively few cases have considered the problem in terms of principle, the Supreme Court and other appellate courts have responded to the application for the writ in such circumstances almost as if the applicant had a right to its issuance.
Id. at 1147. We therefore held that “if a district court exceeds the scope of its judicial authority, the aggrieved party should be granted the writ almost as a matter of right.” Id. 20
*546
We previously have issued writs of mandamus to compel district courts to vacate unauthorized sentence reduction orders.
See, e.g., United States v. Norton,
E. Conclusion
Based on the foregoing discussion, we GRANT (1) Dean’s motion to dismiss the government’s appeal, and (2) the government’s petition for a writ of mandamus to compel the district court to reinstate the. defendant’s original sentence. The remaining motions are DENIED.
APPEAL DISMISSED; WRIT OF MANDAMUS ORDERED TO ISSUE.
Notes
The statutes and rules discussed in this opinion are those that were in effect when the relevant event occurred. The Comprehensive Crime Control Act of 1984, Pub.L. No. 98-473, 98 Stat. 1837 (1984), which was signed into law on October 12, 1984, drastically revises the procedures for sentencing federal criminal defendants. Under Chapter II of the Crime Control Act, also designated as the Sentencing Reform Act of 1984, sentences will be imposed by the district courts pursuant to guidelines established by the newly created United States Sentencing Commission. Id. at §§ 211-12,
. The facts and circumstances of Dean’s crimes are not relevant to the issues before us. A recitation of those facts is contained in the opinion of the former Fifth Circuit on Dean’s direct appeal from his conviction.
See United States v. Dean,
. The sentence imposed by the district court did not exceed the maximum sentence authorized by the statutes under which Dean was convicted.
. Rule 35(b) provides:
(b) Reduction of Sentence. The court may reduce a sentence within 120 days after the sentence is imposed or probation is revoked, or within 120 days after receipt by the court of a mandate issued upon affirmance of the judgment or dismissal of the appeal, or within 120 days after entry of any order or judgment of the Supreme Court denying review of, or having the effect of upholding, a judgment of conviction or probation revocation. Changing a sentence from a sentence of incarceration to a grant of probation shаll constitute a permissible reduction of sentence under this subdivision.
Although Dean did not specify the subdivision of Rule 35 under which his September 15, 1982 motion was made, it is apparent from the content of the motion that Dean was requesting reduction of his sentence under Rule 35(b), and not correction of an illegal sentence under Rule 35(a).
. Rule 35(a) provides:
(a) Correction of Sentence. The court may correct an illegal sentence at any time and may correct a sentence imposed in an illegal manner within the time provided herein for the reduction of sentence.
. The Parole Commission’s decision apparently was based on the Commission’s view of the seriousness of Dean’s crimes. Dean does not challenge the validity of the Parole Commission’s determination of his parole eligibility.
. The district court entered the following order:
ORDER
Roscoe Emory Dean, Jr. was convicted, after a jury trial in this court, on May 14, 1980. His conviction was substantially affirmed by the Fifth Circuit Court of Appeals Unit B on January 22, 1982.
The defendant has filed a motion to reconsider the denial of his motion pursuant to Rule 35 of the Federal Rules of Criminal Procedure.
After due consideration thereof, the sentence of confinement heretofore entered is modified to be limited to time already served by the defendant, and he is ordered released *539 instanter. All other provisions of said sentence heretofore rendered are to remain in full force and effect.
SO ORDERED, this 5th day of April, 1984.
Dean has chosen on appeal to treat the district court's order as one granting relief under Rule 35(a). In any event, we note that the court could not properly have granted relief to Dean under Rule 35(b). The Supreme Court has held that the 120-day time limit contained in Rule 35(b) is jurisdictional.
United States v. Addonizio,
We also note that the 120-day limit applies even where the district court purports to reconsider an earlier, timely Rule 35(b) motion.
See Norton,
. No. 84-8386, filed May 2, 1984.
. No. 84-8475, filed June 11, 1984.
. 28 U.S.C. § 1291 provides, in pertinent part:
The courts of appeals ... shall have jurisdiction of appeals from all final decisions of the district courts of the United States, ... except where a direct review may be had in the Supreme Court.
. The Eleventh Circuit, in the
en banc
decision
Bonner v. City of Prichard,
. In Denson, as in the instant case, the government also filed a petition for a writ of mandamus under Rule 21 of the Federal Rules of Appellate Procedure. See infra note 20.
. On rehearing
en banc,
the former Fifth Circuit affirmed and reinstated the portion of the panel opinion concerning the dismissal of the government’s appeal.
Denson,
The
Denson
panel opinion also discussed the Criminal Appeals Act, 18 U.S.C. § 3731, which enumerates certain instances in which the government may bring an appeal in a criminal case. Although 18 U.S.C. § 3731 was enacted “to remove all statutory barriers to Government appeals and to allow appeals whenever the Constitution would permit,"
United States v. Wilson,
. The government cites United States v. Krohn, 700 F.2d 1033 (5th Cir.1983), for the proposition that, under 28 U.S.C. § 1291, sentence reduction orders entered in Rule 35 proceedings are distinguishable from original sentencing orders. In Krohn, the current Fifth Circuit entertained the government's appeal from a sentence reduction order entered in a Rule 35 proceeding. Id. at 1035. The court did not discuss the appellate jurisdiction issue, however, nor did the court even mention Denson. We therefore decline to give precedential weight to Krohn on the appellate jurisdiction issue.
We acknowledge that at least three other circuits have ruled that the government may ap
*541
peal sentence reduction orders entered under Rule 35.
See United States v. DeMier,
. One exception to this general rule is that a prior decision not "on the merits" will have
res judicata
effect as to issues that were actually decided.
See Aeree v. Air Line Pilots Ass’n,
. We emphasize that our holding is based on the unique procedural circumstances of this case, and does not authorize generally the refiling of previously denied petitions for writs of mandamus. We express no opinion concerning whether, in general, the prior denial of a petition for a writ of mandamus may preclude a court from reaching the merits of a subsequent petition seeking the same remedy.
. The government filed its appeal on May 2, 1984, less than one month after the entry of the sentence reduction order.
. The facts in
Addonizio
were strikingly similar to those in the instant case. Addonizio, the former mayor of Newark, New Jersey, was convicted of conspiracy to commit extortiоn along with numerous substantive counts of extortion. He was sentenced to 10 years in prison. After serving 57 months, Addonizio received a hearing before the Parole Commission, but the Parole Commission denied him parole. The district court that had originally sentenced Addonizio then granted him relief under 28 U.S.C. § 2255, a statute permitting collateral attack on a sentence "imposed in violation of the Constitution or laws of the United States.” The district court stated that its decision to grant relief un
*544
der 28 U.S.C. § 2255 was based on the court’s frustrated expectation, at the time the original sentence was issued, that Addonizio would likely serve between three-and-one-half and four yеars in prison. The Third Circuit affirmed,
Addonizio v. United States,
. We do not find it significant that
Addonizio
involved a challenge to the legality of the sentence under 28 U.S.C. § 2255, whereas the instant case involves a Rule 35(a) motion to correct an illegal sentence. Although the Supreme Court in
Addonizio
emphasized the limited scope of collateral attack on final judgments under section 2255,
see
. In his Rule 35 motion, Dean relied heavily on the case of
United States v. DeMier,
.
The panel opinion in
Denson
had previously indicated that mandamus was thе proper remedy for an unlawful sentence. Nevertheless, the panel had declined to issue a writ of mandamus on the grounds that mandamus was an "extraordinary remedy” not warranted by the facts.
Denson,
On rehearing
en banc,
the former Fifth Circuit acknowledged that “[d]iscretion might be inherent in the writ.”
Denson,
. We also note that the Third Circuit has recently held that mandamus, not appeal, is the proper remedy when a district court improperly grants an untimely motion for reduction of sentence under Rule 35(b).
See United States v. Ferri,
. As in
Norton
and
Mehrtens,
we find that formal issuance of the writ is not deemed necessary to assure the district court's compliance. A copy of this opinion issued as a mandate should suffice.
See Norton,
