What Is a Federal 5K1 Motion for Sentence Reduction?

A federal 5K1 motion is a request the prosecutor files asking the judge to sentence a defendant below the normal guidelines range — and, when the statute allows, below a mandatory minimum — because that defendant provided substantial assistance in investigating or prosecuting someone else. The name comes from Section 5K1.1 of the U.S. Sentencing Guidelines. In fiscal year 2024, about 9.9% of all sentenced federal defendants received this type of departure.¹

The Two Provisions Behind the Motion

“5K1 motion” is shorthand for two legal tools that often travel together. Section 5K1.1 of the U.S. Sentencing Guidelines lets a judge impose a sentence below the recommended guidelines range when the government certifies that the defendant provided substantial assistance.² Many federal offenses, though, also carry mandatory minimums set by Congress, and a guidelines departure by itself cannot break through that statutory floor.

That is the job of 18 U.S.C. §3553(e). It authorizes the court to sentence below a mandatory minimum specifically to reflect a defendant’s substantial assistance in the investigation or prosecution of another person.³ When a prosecutor files a 5K1 motion, they may invoke §5K1.1, §3553(e), or both, depending on how they value the cooperation and whether a mandatory minimum applies.

Only the Prosecutor Can File

A defendant cannot file a 5K1 motion. Neither can defense counsel. Under both §5K1.1 and §3553(e), the court’s authority to reduce a sentence is triggered only “upon motion of the government.”³ That gives federal prosecutors substantial leverage. A defendant can cooperate at length and still receive no motion if the prosecutor decides the assistance was not valuable enough.

Most 5K1 motions come out of plea agreements. The defendant agrees to provide full and truthful cooperation, and the government agrees to consider filing the motion at sentencing. “Consider” is the operative word. These agreements typically reserve sole discretion to the government to decide whether and when to file, and a prosecutor who concludes the cooperation fell short can simply decline.

The Supreme Court in Wade v. United States held that federal judges may review a refusal to file, but only in narrow situations: the defendant has to show the refusal rested on an unconstitutional motive such as race or religion, or that it bore no rational relationship to a legitimate government interest. Substantial assistance is a necessary condition for relief, not a sufficient one, and generalized claims of improper motive do not even get the defendant a hearing.⁴ Successful challenges are rare.

What Counts as Substantial Assistance

There is no checklist. Substantial assistance means the defendant did something that meaningfully helped the government investigate or prosecute someone else. Common forms include providing truthful information about criminal activity, identifying co-conspirators, helping locate evidence or criminal proceeds, and testifying before a grand jury or at trial. Vague or unreliable tips will not qualify.

The government weighs not just what the defendant said but how useful it turned out to be. A name that leads to a major arrest counts for more than confirmation of facts the government already had. Timing matters too. Early cooperation that shapes the direction of an investigation carries more weight than information offered after the other dominoes have already fallen.

The Proffer Process

Cooperation usually runs through proffer sessions, sometimes called “queen for a day” meetings. The defendant sits down with the prosecutor and investigating agents and lays out what they know. Defense counsel is present and can pause the session for private consultation, but the prosecutor and agents lead the questioning.

Before the meeting, the parties sign a proffer agreement setting the ground rules. The core protection is that the government cannot use the defendant’s proffer statements in its case-in-chief. The protections have real gaps, though. The government may follow up on leads generated by the proffer and use whatever new evidence those leads produce. If the defendant later testifies inconsistently with what they said during the proffer, the statements can be used for impeachment. And if the prosecutor believes the defendant lied during the session, that can support a charge for making false statements.

A proffer gives the government a detailed preview of the defendant’s knowledge, their demeanor under pressure, and their theory of the case. Walking in without competent counsel or without being fully prepared is one of the most dangerous things a federal defendant can do.

How the Judge Decides the Size of the Reduction

Once the government files the motion, the judge is not required to grant any particular reduction. The Sentencing Guidelines list five factors the court should weigh:²

The significance and usefulness of the assistance, factoring in the government’s own assessment
The truthfulness, completeness, and reliability of the information or testimony
The nature and extent of what the defendant actually did — passing a tip, wearing a wire, testifying at trial
Any injury or risk of injury to the defendant or their family from cooperating
The timeliness of the assistance

The guidelines describe these factors as non-exhaustive. The government’s recommendation carries weight, but the judge makes the final call on how far below the guidelines range or mandatory minimum to go. There is no fixed percentage or number of levels; a 5K1 departure can reduce a sentence to probation or time served, depending on the circumstances. Sentencing Commission data cited in the file suggests substantial-assistance departures typically reduce sentences by roughly 50% to 60% below the bottom of the guidelines range, though the variation is wide.

Cooperation That Happens After Sentencing

A 5K1.1 motion has to be filed before or at sentencing. If the cooperation becomes valuable only after that, Federal Rule of Criminal Procedure 35(b) is the corresponding tool. The government can move to reduce the sentence based on substantial assistance provided after sentencing, and the court can go below a statutory minimum, just as with a 5K1.1 motion.⁵

The motion generally has to be filed within one year of sentencing. After that, it is permitted only in limited situations — for example, when the defendant learned the information more than a year out, or when information provided within the first year did not become useful until later.⁵ For this rule, “sentencing” means the oral pronouncement of the sentence, not the entry of the written judgment.

Not the Same as the Safety Valve

A 5K1 motion is often confused with the federal “safety valve,” but they work differently. The safety valve, at 18 U.S.C. §3553(f), lets a judge sentence below a mandatory minimum for certain drug offenses without any government motion; the defendant qualifies on their own by meeting statutory criteria that include a limited criminal history, no violence or firearm, no leadership role, and a truthful disclosure of their own conduct.⁶ It only applies to specific drug trafficking and possession offenses. A 5K1 motion, by contrast, requires the prosecutor to file, requires helping the government against someone else, and is available in any federal case where substantial assistance is provided.

1
United States Sentencing Commission. Table 29 – 2024 Sourcebook of Federal Sentencing Statistics
2
United States Sentencing Commission. 2025 Guidelines Manual – Chapter 5
3
Office of the Law Revision Counsel. 18 USC 3553 – Imposition of a Sentence
4
Justia. Wade v United States, 504 US 181
5
Legal Information Institute. Federal Rules of Criminal Procedure Rule 35 – Correcting or Reducing a Sentence
6
Congressional Research Service. Federal Mandatory Minimum Sentences – The Safety Valve