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Risks of Proffering
The proffer is the most dangerous voluntary act in federal criminal defense.
Clients reach this office, in most instances, having already been told that cooperation is their only path. An AUSA has extended the invitation. Defense counsel, sometimes without conducting a full assessment of the government’s evidence, has advised the client to accept. The proffer letter, typically six to eight pages, has been signed. And the session, once concluded, cannot be reversed.
What follows is not an argument against cooperation. Cooperation, under the right conditions, remains one of the few mechanisms by which a defendant facing substantial exposure can achieve a sentence that preserves something of an ordinary life. The argument is narrower: the proffer agreement, as most federal districts draft it, offers protections that are thinner than the document’s length and formality would suggest, and the risks it creates are ones that most defendants do not perceive until those risks have already materialized.
The Structure of a Proffer Agreement
Federal Rule of Evidence 410 and Federal Rule of Criminal Procedure 11(f) were designed to encourage plea negotiations by excluding a defendant’s statements in those negotiations from use at trial. The proffer agreement overrides them. Under the standard letter used by most U.S. Attorney’s Offices, the defendant waives the protections of both rules and agrees to answer questions under conditions governed by the letter itself rather than by the statute.
The Supreme Court approved this waiver in United States v. Mezzanatto. The holding was that an agreement to waive the plea-statement exclusionary provisions is valid and enforceable so long as the defendant entered it knowingly and voluntarily. Justice Ginsburg, concurring, expressed concern that extending the waiver beyond impeachment use could discourage defendants from entering plea bargains at all.
Her concern was prescient. In the years since Mezzanatto, the Second Circuit in United States v. Velez extended the waiver to cover all defense evidence and arguments, not merely the defendant’s own testimony. The Seventh Circuit, in United States v. Krilich, reached a comparable conclusion. The D.C. Circuit, in United States v. Burch, found no limiting principle and permitted the use of proffer statements in the government’s case-in-chief. The proffer letter, which began as a limited accommodation to facilitate plea discussions, has become something closer to a broad waiver of the defendant’s trial rights.
What the letter promises, in most districts, is that the government will not use the defendant’s statements “in its case-in-chief.” That phrase carries a precision most clients do not register.
Derivative Use and the Kastigar Waiver
The Kastigar waiver, which appears in nearly every proffer letter, permits the government to pursue any investigative leads generated by the defendant’s statements. The statements themselves may not be introduced. The evidence those statements produce may be.
The Eleventh Circuit addressed this in United States v. Pielago and concluded that proffered information could generate independent evidence usable against the defendant without limitation. The practical consequence is not abstract. If a defendant, in the course of a proffer session, mentions a bank account, a document, or a meeting with a co-conspirator, the government may subpoena the records of that account, obtain that document, and introduce the fruits of that meeting at trial. The proffer letter does not require the government to demonstrate, as it would under Kastigar v. United States in a statutory immunity context, that its evidence was derived from a source independent of the defendant’s words. The waiver eliminates that requirement.
This is the mechanism by which a defendant can, in the course of a single afternoon, provide the government with evidence it did not possess and would not have obtained without the defendant’s participation, while believing that the session has placed them in a more favorable position. That understanding is usually incorrect.
I am less certain about the uniformity of this outcome across every federal circuit than the preceding paragraph might suggest. The circuits that have addressed the derivative use waiver have tended to favor the government’s reading, but the question of whether every district applies it with equal rigor is one this firm cannot answer from the cases it has reviewed. What we can state is that the standard proffer letter, in its present form, is drafted to permit derivative use, and that defense counsel who proceeds without addressing this provision has accepted a risk that the client almost certainly does not comprehend.
Sentencing Exposure
The proffer agreement’s promise to exclude the defendant’s statements from the government’s case-in-chief does not extend to sentencing. This distinction is, if we are being precise, the one that produces the greatest measurable harm.
Under the federal sentencing guidelines, the court considers all “relevant conduct” when calculating the offense level. Relevant conduct includes criminal activity that was part of the same course of conduct or common scheme, regardless of whether it was charged. During a proffer session, prosecutors will ask about everything adjacent to the offense under investigation. The defendant, required by the agreement to answer with complete truthfulness, may describe conduct spanning years and involving amounts that exceed the charged offense.
A defendant charged with a fraud count involving a particular sum may, in the proffer room, acknowledge a pattern of similar transactions. The loss amount for sentencing purposes expands. The sentencing range shifts. The cooperation credit the defendant hoped to receive may not offset the exposure that the proffer itself created.
We approach the sentencing calculation before the proffer takes place, not after. The sequence most firms follow is to prepare the client for the session and address the sentencing implications at the presentence stage. Our experience has been that this order produces worse outcomes, because once the relevant conduct has been disclosed, it cannot be undisclosed, and the presentence report will reflect it regardless of whether cooperation succeeds.
What Mezzanatto Permits
The breadth of the waiver clause in a standard proffer agreement can, under certain conditions, prevent the defendant from mounting a defense at trial.
Consider the following: a defendant proffers and admits to possessing a firearm. The proffer session does not result in a cooperation agreement. The case proceeds to trial. Defense counsel intends to call a witness who would testify that the firearm belonged to another individual. Under the standard waiver clause, which permits the government to introduce proffer statements to rebut “any evidence or arguments offered by or on behalf of the defense,” the government may introduce the defendant’s admission. Defense counsel, recognizing this consequence, declines to call the witness.
The constraint extends to cross-examination. In Velez, the Second Circuit held that questions posed by defense counsel to government witnesses could trigger the rebuttal clause. The defense attorney (who, it should be noted, must make this calculation in real time for every question posed, weighing whether each line of inquiry might open the door to the admission of the defendant’s proffer statements while simultaneously attempting to construct a coherent cross-examination that serves the client’s interests) faces a trial in which significant portions of the government’s case may go uncontested. Defense counsel may advise the defendant against testifying. All to prevent the proffer statements from reaching the jury.
Whether the court intended this outcome or merely failed to prevent it is a question worth considering.
Justice Souter’s dissent in Mezzanatto anticipated the erosion: the possibility of trial, if no agreement is reached, “will be reduced to fantasy.” The proffer letter, signed in a conference room at the U.S. Attorney’s Office on what was supposed to be a preliminary meeting, can operate as a waiver not only of evidentiary protections but of the capacity to contest the charges at all. The room where the proffer takes place is quiet, institutional, and smaller than most clients expect. There is a water pitcher on the table that no one touches.
The Non-Signatory Problem
A proffer agreement binds its signatories. In most districts, the signatories are the U.S. Attorney’s Office and the defendant.
The agreement does not bind state prosecutors. It does not bind foreign authorities. It does not bind other federal agencies conducting parallel investigations. And the standard letter, as most offices draft it, contains no provision restricting the sharing of proffered information with entities that are not parties to the agreement.
In the present enforcement environment, overlapping investigations by federal, state, and foreign authorities have become ordinary. A defendant proffers to the U.S. Attorney in one district. The Department of Justice shares information with a state attorney general’s office investigating the same conduct. The state office, not being a signatory, faces no contractual restriction on its use of that information. The protection the defendant understood to exist has a boundary the defendant was not told about.
This gap has received attention in recent practice commentary. The standard proffer letter has not been revised to address it. Counsel can attempt to negotiate language restricting dissemination, but the government is not obligated to agree, and in cases where the defendant’s bargaining position is limited, the request may be declined without discussion.
When Proffering May Be Appropriate
There are cases in which proffering is the least harmful option. The evidence is overwhelming. The client possesses information of genuine value regarding individuals further up in the organization. The sentencing exposure without cooperation is severe enough that the risk of the proffer is outweighed by the certainty of what a post-trial sentence would produce. In these cases, the proffer is not safe; it is merely less dangerous than the alternative.
The assessment requires knowing what the government already possesses. If the case is strong but the client’s information is marginal, the proffer exposes without compensating. The client provides statements in exchange for cooperation credit that may not materialize, because the government, having determined that the client’s information was not sufficiently valuable, is under no obligation to file a 5K1.1 motion.
Something like seven of the proffer sessions we have declined to participate in over the past several years involved clients whose prior counsel had recommended proffering without first assessing the strength of the government’s existing evidence. In each instance, the government’s case was weaker than the client believed, and the proffer would have supplied what the government lacked.
The proffer agreement occupies a space in federal criminal practice where the language of protection and the reality of exposure coexist without acknowledgment of the distance between them. The letter is formal. The immunity is real, though not as extensive as the word suggests. The exceptions to that immunity are where the consequences live, and those exceptions are not described in any clause the defendant will be asked to sign.
A consultation is where that assessment begins, and where the decision about whether to enter that room is made with the full measure of what the room contains.