Can a Judge Change a Sentence After It Has Been Imposed?

Yes, a judge can change a sentence after it has been imposed, but only in narrow situations spelled out by statute or rule. Federal law starts from the opposite presumption: 18 U.S.C. 3582(c) opens with the words “The court may not modify a term of imprisonment once it has been imposed” before listing a short set of exceptions.¹ Those exceptions, together with post-conviction motions, appeals, and executive clemency, are the only paths to a different sentence. Each has its own deadline, and a missed deadline usually ends the matter.

What follows walks through those paths in the order they tend to matter: the fastest fixes first, then the broader remedies, then the routes that live outside the courts.

Fixing Errors in the First 14 Days

The shortest window belongs to Rule 35(a) of the Federal Rules of Criminal Procedure. Within 14 days of sentencing, the court can correct a sentence that resulted from arithmetical, technical, or other clear error.² Think 120 months entered when the judge said 12, or a miscalculated guidelines range. Rule 35(a) is not a chance to rethink the sentence. When those 14 days pass, this option is gone.

A related rule, Rule 36, handles clerical mistakes in the written judgment itself, such as a misspelled name or the wrong statute of conviction on the paperwork. Rule 36 has no deadline; the court can correct a clerical error “at any time.”³ The line between the two: Rule 36 fixes the paperwork, Rule 35(a) fixes the substance of the sentence.

Sentence Reductions for Helping the Government

Rule 35(b) lets the court reduce a sentence when a defendant provides substantial assistance to the government after sentencing, such as testimony or information used to investigate or prosecute someone else. One point catches many defendants off guard: only the government can file this motion. A defendant cannot request a Rule 35(b) reduction on their own.²

The government generally has to file within one year of sentencing. A later motion is still possible, but only if the useful information involved conduct the defendant did not know about until more than a year after sentencing, or conduct that occurred more than a year after sentencing.²

Compassionate Release

Compassionate release under 18 U.S.C. 3582(c)(1)(A) is probably the broadest exception to finality. The court can reduce a sentence when “extraordinary and compelling reasons” justify it, but there is a gatekeeper step. Before going to court, the defendant must ask the warden of their facility to bring the request on their behalf. Only after exhausting administrative appeals within the Bureau of Prisons, or waiting 30 days from the warden’s receipt of the request, can the defendant file directly with the court.¹

The Sentencing Commission’s November 2023 policy statement lists the recognized categories of extraordinary and compelling reasons:

Terminal illness — a serious, advanced disease with an end-of-life trajectory. No specific life-expectancy prognosis is required.
Serious medical conditions — physical or cognitive impairments that substantially limit self-care in prison and from which recovery is not expected, or a condition requiring specialized care the facility is not providing.
Age — the defendant is at least 65, has serious health deterioration tied to aging, and has served at least 10 years or 75 percent of the sentence, whichever is less.
Family circumstances — the death or incapacitation of the caregiver for the defendant’s minor child, or the incapacitation of a spouse when the defendant is the only available caregiver.
Infectious disease outbreaks — the defendant is housed at a facility affected by an ongoing outbreak or public health emergency and faces heightened personal risk that cannot be adequately mitigated.

A separate track exists for elderly inmates serving very long terms. Defendants at least 70 years old who have served at least 30 years can petition for release if the Bureau of Prisons determines they are not a danger to the community.¹ Even when a defendant fits a category, the court still weighs the sentencing factors in 18 U.S.C. 3553(a), including the seriousness of the offense and public safety, before reducing a sentence.⁴

When Sentencing Rules Change

Sentencing guidelines are not fixed. When the U.S. Sentencing Commission lowers the range for an offense, defendants sentenced under the older, higher range can ask the court for a corresponding reduction under 18 U.S.C. 3582(c)(2). The defendant, the Bureau of Prisons, or the court itself can start the process.⁵ The reduction is not automatic. The court applies the sentencing factors and must find that the change fits the Commission’s policy statements.

Congress sometimes goes further and makes new sentencing laws retroactive. Section 404 of the First Step Act of 2018 let defendants sentenced under the old crack cocaine guidelines petition for resentencing under the fairer ratios of the Fair Sentencing Act of 2010, and thousands of inmates received reductions. The practical point: when Congress or the Commission changes the rules, someone still has to file the motion.

Post-Conviction Motions Under 28 U.S.C. 2255

The main tool for challenging a federal sentence after conviction is a motion under 28 U.S.C. 2255. It is sometimes called a habeas petition, but the statute’s own legislative history describes it as “an expeditious remedy for correcting erroneous sentences without resort to habeas corpus.”⁶ True habeas corpus under 28 U.S.C. 2241 is available only when the 2255 remedy is “inadequate or ineffective.”

A 2255 motion is available when the sentence was imposed in violation of the Constitution or federal law, when the court lacked jurisdiction, when the sentence exceeded the statutory maximum, or when the sentence is otherwise open to collateral attack. If the court agrees, it can vacate, set aside, or correct the sentence.⁶

Common Grounds

Constitutional claims are common. A defendant may argue that the sentence is grossly disproportionate to the offense under the Eighth Amendment, or that trial counsel was so deficient under the Sixth Amendment that the sentencing outcome was affected. The bar for ineffective assistance is high: you must show both that counsel’s performance fell below professional standards and that the deficiency changed the result.

Newly discovered evidence can also support a 2255 motion, provided the defendant could not have found it earlier through reasonable diligence and it would have materially affected the outcome.

The One-Year Clock and Second Motions

A 2255 motion must be filed within one year. The clock starts from the latest of four events: when the conviction becomes final, when a government-created obstacle to filing is removed, when the Supreme Court recognizes a new constitutional right and makes it retroactive, or when the supporting facts could have been discovered through due diligence.⁶ Courts can extend the deadline through equitable tolling only in truly extraordinary circumstances, and unfamiliarity with the law does not qualify.

A second 2255 motion is much harder. Under the Antiterrorism and Effective Death Penalty Act, it must first be certified by a panel of the court of appeals. Certification requires either newly discovered evidence that would clearly establish innocence, or a new rule of constitutional law that the Supreme Court has made retroactive.⁶

Appeals and Resentencing

A defendant who believes the sentencing judge made a legal or procedural error can file a notice of appeal within 14 days of the judgment.⁷ The appellate court does not redo sentencing. It reviews for procedural soundness and substantive reasonableness under an abuse-of-discretion standard, and a within-guidelines sentence carries a presumption of reasonableness.⁸

If the court finds an error, it typically vacates the sentence and remands for a new sentencing hearing bound by the appellate court’s instructions. Common errors leading to remand include miscalculating the guidelines range, relying on improper factors, or failing to explain the sentence adequately.⁹

Can a Sentence Go Up?

Yes, in some situations. Within the 14-day Rule 35(a) window, correcting a clear error can move the sentence in either direction, so a miscalculation that produced too low a term could be corrected upward. After 14 days, the government’s route to a higher sentence is an appeal. Under 18 U.S.C. 3742(b), the government can appeal a sentence imposed in violation of law, based on an incorrect guidelines application, below the applicable guidelines range, or plainly unreasonable. The appeal requires personal approval from the Attorney General or Solicitor General.⁹

When a defendant wins an appeal, is retried and convicted again, and is resentenced, the judge can impose a harsher term. But the Supreme Court held in North Carolina v. Pearce that due process bars vindictive sentencing. A higher sentence must rest on objective reasons based on conduct that occurred after the original sentencing; otherwise a presumption of vindictiveness applies.

Executive Clemency

Every route above runs through a court. Executive clemency does not. The President has constitutional authority to commute federal sentences, substituting a less severe punishment for the one imposed. A commutation, unlike a pardon, leaves the conviction intact and reduces or ends the remaining prison time.¹⁰

Petitions go to the Office of the Pardon Attorney at the Department of Justice, which investigates and makes a recommendation to the President. Federal regulations state that a commutation petition generally should not be filed while other judicial or administrative remedies are still available, absent exceptional circumstances.¹¹ Governors hold similar power over state sentences, though procedures and any pardon-board role vary widely by state.

Good Conduct Time: Not a Sentence Change

Good conduct time is worth naming because people often confuse it with a sentence change. It is not. The judge’s sentence stays what it was; the credits affect how much of it is actually served. Under the First Step Act, federal inmates can earn up to 54 days of credit for each year of the sentence imposed. To earn the full 54 days, the inmate must have earned or be making satisfactory progress toward a high school diploma, GED, or a Bureau-authorized alternative. Without meeting that requirement, credits are capped at 42 days per year.¹²

A Note on State Sentences

Everything above is federal law. State courts have their own systems for changing sentences after imposition, and they vary widely. At least 42 states allow inmates to earn credits for good behavior or program participation, with the rates and eligible offenses differing by state. Many states also have compassionate release programs, often routed through a parole board rather than the sentencing judge, that require detailed medical documentation and a public-safety finding. State post-conviction remedies allow challenges based on newly discovered evidence, ineffective assistance, or changes in the law, each with its own filing deadline. Anyone pursuing a modification at the state level should identify the specific procedural rules in that jurisdiction early, because the window for action can be short.

1
Office of the Law Revision Counsel. 18 USC 3582 – Imposition of a Sentence of Imprisonment
2
Cornell Law School. Rule 35 – Correcting or Reducing a Sentence
3
Cornell Law School. Rule 36 – Clerical Error
4
U.S. Sentencing Commission. Official Text of 2023 Amendments
5
Office of the Law Revision Counsel. 18 USC 3582 – Imposition of a Sentence of Imprisonment
6
Office of the Law Revision Counsel. 28 USC 2255 – Federal Custody; Remedies on Motion Attacking Sentence
7
Cornell Law School. Rule 4 – Appeal as of Right; When Taken
8
Cornell Law School. Appellate Review of Federal Sentencing Determinations
9
Office of the Law Revision Counsel. 18 USC 3742 – Review of a Sentence
10
Cornell Law School. Commutations, Remissions, and Reprieves
11
eCFR. Part 1 – Executive Clemency
12
Federal Register. Good Conduct Time Credit Under the First Step Act