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What Is "Derivative Use" in a Proffer Agreement?
Derivative use is the provision in a proffer agreement that most defense attorneys explain too late. The term occupies a single paragraph in the standard federal proffer letter, situated between the clauses governing direct use immunity and the provisions for impeachment. What it permits is this: the government may pursue any investigative lead your statements suggest, and any evidence obtained through those leads may be introduced against you at trial, at sentencing, or in any subsequent proceeding.
The protection a proffer letter extends is not a fabrication. Your statements, as recorded during the session, cannot appear in the government’s case in chief. The government cannot place a transcript of your proffer before the jury. That much is accurate, in the narrowest possible sense.
Your words are protected. What your words reveal is not.
The Scope of “Case in Chief”
“Case in chief” is a term of art, and it is narrower than it sounds. It refers to the government’s initial presentation of evidence at trial: the portion of the proceeding in which the prosecution lays out its affirmative case before the defense has spoken. The phrase does not encompass rebuttal evidence, which the government may introduce if your trial testimony contradicts your proffer. It does not encompass sentencing, where proffer statements can inform the calculation of your offense level under the Federal Sentencing Guidelines. It does not encompass impeachment, where any inconsistency between what you told the agents and what you tell the jury becomes an instrument for dismantling your credibility.
These exceptions are stated in the letter. Defense counsel who has reviewed proffer agreements before will recognize the language. The exception that receives less scrutiny, and warrants more, is derivative use.
How the Government Uses What You Disclose
A proffer session operates, in practice, as a directed interview. Prosecutors and agents pose questions. The defendant responds. Counsel is present. The questions are expansive, the expectation is completeness, and the session can extend for several hours. During that time, a defendant may disclose the names of individuals the government had not yet identified, the existence of financial accounts or transactions that had not yet surfaced in the investigation, or the location of documents and communications the government did not know existed.
Under the derivative use clause, the government may pursue every one of those leads. The agents may subpoena the financial records you mentioned. They may interview the individuals you named. They may obtain documents you described. And the evidence recovered through those leads, because it was obtained independently of your direct statements, is admissible against you.
The word “independently” is performing considerable labor in that sentence.
In 1972, the Supreme Court in Kastigar v. United States held that use and derivative use immunity satisfies the Fifth Amendment because it places the witness in substantially the same position as if the privilege had been claimed. The government, should it later prosecute an immunized witness, must demonstrate that every piece of evidence it introduces was derived from a legitimate source wholly independent of the compelled testimony. This burden, the Court stated, is an affirmative one.
The Kastigar framework, if honored, is a meaningful safeguard. The standard federal proffer letter is designed to function outside that framework. The proffer letter includes what practitioners call a Kastigar waiver. By signing the letter, the defendant waives the right to a Kastigar hearing: the proceeding at which the government would be required to prove that its evidence was obtained independently of the defendant’s statements. The waiver eliminates the mechanism through which the protection would be enforced.
What remains is a contractual permission for the government to follow your leads and introduce whatever those leads produce, with no obligation to demonstrate that the evidence would have been discovered without your cooperation.
The proffer letter promises that your words will not be used against you. The Kastigar waiver ensures that the consequences of your words will be.
The D.C. Circuit’s decision in United States v. North illustrates what occurs when Kastigar protections remain intact. Oliver North (who, it should be noted, had been compelled to testify on national television for six days under a congressional grant of use and derivative use immunity, with the Independent Counsel objecting to the grant before a single question was asked) was subsequently prosecuted and convicted on three counts. The D.C. Circuit reversed those convictions because the prosecution could not establish that its witnesses had not been influenced by North’s immunized testimony. The government’s failure to satisfy the Kastigar burden proved fatal to the prosecution.
Whether the D.C. Circuit intended to establish a principle that would render most federal proffers functionally unprotected, or whether it was addressing the particular contamination of a case broadcast to millions, is a question the opinion does not resolve.
The government insists on Kastigar waivers in proffer letters to prevent precisely this outcome (which opponents of the current proffer system will characterize as inherently coercive, though courts in every circuit to address the question have enforced the waiver as a valid contractual provision). The practical consequence is that if cooperation fails and the case proceeds to trial, the government possesses both the leads your proffer generated and the contractual freedom to use what those leads produced without accounting for their origin.
The Debt That Comes Due
Whether to proffer despite the derivative use risk is, if we are being precise, not a legal question. It is an actuarial one. The calculation requires an assessment of the evidence the government already holds, the exposure the defendant confronts if convicted at trial, the realistic probability that the proffer will result in a cooperation agreement or a plea, and the extent to which the defendant’s information is information the government does not already possess.
A defendant who can offer testimony against individuals the government has been unable to reach occupies a position of some leverage. A defendant whose information confirms what the government already knows provides less value, and the derivative use risk is less severe, because the leads are leads the government was already following. The danger concentrates where the defendant possesses information that opens investigative avenues the government had not contemplated.
The first letter or call from a prosecutor arrives, in most cases, when cash flow is already strained and the business owner has already made at least one decision without counsel. The instinct is to cooperate, to appear forthcoming, to resolve the situation before it becomes something worse. You sign the proffer letter because the alternative feels like refusal, and refusal feels like guilt. That instinct is precisely what the proffer system relies on.
In something like seven of every ten proffer sessions we have prepared clients for, the government possessed more evidence than the client believed it did when the client first consulted us. The assessment is not scientific; it comes from a body of cases, not a database. But the pattern is consistent enough to be a principle: the gap between what a defendant perceives the government knows and what the government actually knows is substantial. The gap runs in one direction.
Negotiation and Preparation
The derivative use clause is standard language. It is not, in every district, immutable language.
Before the proffer letter is signed, experienced defense counsel can attempt to negotiate limitations on the scope of derivative use. The success of those negotiations depends on the district, the prosecutor, and the value the government assigns to the defendant’s cooperation. In some cases, counsel can restrict derivative use to the specific subject matter of the proffer, preventing the government from pursuing leads related to criminal conduct the defendant disclosed but that falls outside the scope of the investigation. In rarer cases, counsel can arrange an attorney proffer, in which the attorney conveys information to the prosecution without the client present, permitting the government to assess the cooperation’s value before the client is exposed to the full derivative use risk.
We approach proffer preparation through what amounts to a reverse investigation. Before any session, we identify what the government already possesses. We map the areas where the client’s information is genuinely new. We assess which disclosures create derivative use exposure and which are confirmatory of evidence the government can already prove through other sources. The obligation to be truthful and complete is absolute, and nothing in our preparation alters that obligation. What the preparation alters is the client’s understanding of where the risk concentrates, so that expectations are accurate and counsel can monitor the session with that map in mind.
Whether every provision of a proffer letter can be negotiated in a given district is a question that depends on facts we cannot generalize from this desk. What we can say is that the derivative use clause is the provision worth the most attention. It is the provision most defense attorneys spend the least time examining.
Every proffer agreement is a wager. The protection the letter offers is real, and the protection the letter withdraws is also real, and the distance between the two is the distance a federal investigation can travel on a single afternoon of cooperation. That distance favors the defendant or the government depending on preparation that occurs before the letter arrives, before the session is scheduled, before the client has determined whether to cooperate at all.
A first consultation assumes nothing and costs nothing. It is the point at which the arithmetic begins.