In federal cases, cooperating with the government is one of the few ways to get a sentence below a mandatory minimum. It usually starts with a proffer, a meeting where the person tells prosecutors and agents what they know. A proffer can help a great deal, and it can also go badly wrong.
This guide explains how proffer agreements work, what protection they really give, how cooperation can reduce a sentence under Section 5K1.1 and Rule 35(b), and how to decide whether cooperating makes sense. It applies in both the Eastern and Western Districts of Missouri.
The meeting
What is a proffer in a federal case?
A meeting, under a written agreement, where the person answers the government’s questions.
A proffer usually takes place at the U.S. Attorney’s Office with the prosecutor, one or more agents, the person, and defense counsel. Before it starts, everyone signs a proffer agreement, sometimes called a “queen for a day” letter, that sets the rules for how the person’s statements can be used.
The government uses a proffer to decide whether the person is truthful, what they know, and whether the information is valuable enough to support a cooperation agreement. The person is expected to answer every question fully and truthfully, including questions about their own conduct.
The protection
Can what I say in a proffer be used against me?
Yes, in more ways than most people expect.
A typical proffer agreement promises that the government will not use the person’s statements directly against them in its main case. But the exceptions are significant, and they vary with the exact wording:
- Leads. The government can usually follow leads from what the person says and use the evidence it finds.
- Impeachment and rebuttal. If the person later testifies or presents evidence inconsistent with the proffer, the statements can usually be used against them. The Supreme Court has held that defendants can waive the usual protection for plea discussions (United States v. Mezzanatto, 1995), and proffer agreements commonly include that waiver.
- False statements. Lying in a proffer can lead to a separate charge for false statements, and it usually ends any chance of cooperation credit.
- Sentencing. Depending on the agreement and the guidelines, information may affect the sentencing calculation.
The practical result: a person who proffers has, in most cases, given up the ability to go to trial and tell a different story. That is why a proffer is not an option for someone who intends to contest guilt.
The payoff
How much does cooperation reduce a federal sentence?
It depends on the value of the assistance, and the government controls the motion.
Before sentencing: Section 5K1.1
If the government files a motion stating that the person provided substantial assistance in investigating or prosecuting others, the judge can sentence below the guideline range. Combined with a motion under 18 U.S.C. § 3553(e), the judge can also go below a mandatory minimum.
After sentencing: Rule 35(b)
Under Rule 35(b) of the Federal Rules of Criminal Procedure, the government can move to reduce a sentence for substantial assistance provided after sentencing, generally within one year, with exceptions for information that became useful later.
Only the government can file these motions, and it decides whether the assistance was substantial. The judge decides how much of a reduction to give. A person can cooperate fully and still not receive a motion if the information did not help.
The decision
Should I cooperate with federal prosecutors?
It depends on the strength of the case and the person’s goals.
Cooperation makes the most sense when the evidence is strong, the sentencing exposure is high, and the person has useful, truthful information. It makes little sense when the person intends to go to trial or has a real defense. In between, it is a judgment that weighs the possible reduction against the risks.
- Safety. Cooperation can carry personal risk, for the person and their family.
- Completeness. The government expects everything, including conduct it did not know about.
- Timing. Information is often most valuable early, before others cooperate.
- The safety valve. In some drug cases, a truthful disclosure for safety-valve purposes is a narrower alternative that does not require a government motion.
See mandatory minimums and the safety valve and federal plea agreements.
FAQ
Proffer and cooperation questions
What is a queen for a day letter?
Another name for a proffer agreement: the written terms under which a person meets with prosecutors and agents. It limits direct use of the statements but usually allows derivative use and use for impeachment or rebuttal.
Can I go to trial after a proffer?
Technically yes, but if the defense contradicts what was said in the proffer, the statements can usually be used against you. In practice, a proffer usually closes off a trial defense inconsistent with it.
Does cooperating guarantee a lower sentence?
No. Only the government can file a substantial assistance motion, and it does so only when it decides the assistance was substantial. The judge then decides the amount of any reduction.
Can cooperation get me below a mandatory minimum?
Yes, if the government files a motion under 18 U.S.C. § 3553(e) or, after sentencing, under Rule 35(b). The safety valve is a separate route in some drug cases.
Should I talk to agents without a lawyer to show I want to cooperate?
No. Statements made without a proffer agreement have no protection at all. A lawyer can find out whether the government is interested and negotiate the terms first.
See our federal criminal defense page, or call 573-638-8529.
Talk to us
Decide before you sit down.
If the government has asked for a proffer, or you are weighing cooperation in a Missouri federal case, call before any meeting.
Attorney advertising. The choice of a lawyer is an important decision and should not be based solely upon advertisements. This article is general information about federal cooperation as of October 2026, not legal advice, and it does not create an attorney-client relationship. Proffer agreements vary, and the outcome of any case depends on its facts.
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