What Does It Mean to Be Granted Immunity?

To be granted immunity means the government has agreed not to use your own words against you in a criminal case, and in some forms of the deal, not to prosecute you at all for the conduct you describe. In exchange, you lose the ability to stay silent. The Fifth Amendment normally lets a witness refuse to answer questions whose truthful answers would be incriminating; an immunity order takes that shield away by promising the testimony cannot hurt you, which leaves you with no legal ground to refuse.¹

That trade is the whole concept. Everything else — how much protection you actually get, what crimes it reaches, whether another government can still come after you — depends on which type of immunity you’re being offered and the terms of the deal.

The Trade at the Heart of Any Immunity Deal

Prosecutors do not grant immunity as a favor. They grant it to get testimony they otherwise cannot compel, almost always because the witness knows something about someone higher up or a more serious offense. At the federal level, a U.S. attorney can only request an immunity order when the testimony “may be necessary to the public interest,” which operates as a check against routine use.²

Once the court communicates the order to you, two things happen at the same moment: the government is bound by whatever protection the order carries, and your right to invoke the Fifth Amendment on the covered subjects is gone.

The Two Main Kinds of Protection

Not every immunity grant protects you the same way. The difference decides whether you can still be charged for the very conduct you testified about.

Use and Derivative Use Immunity

This is what federal law provides, and it’s what most witnesses actually get. Prosecutors cannot use your compelled testimony against you, and they cannot use any evidence they found as a result of that testimony. Tell a grand jury where the money is buried, and neither your statement nor the money dug up because of it can be introduced in a case against you.¹

You can, in theory, still be prosecuted for the same offense if the government builds its case entirely from independent sources. The Supreme Court held in Kastigar v. United States that this form of immunity is broad enough to replace the Fifth Amendment and compel testimony, but the Court placed a heavy burden on prosecutors: in any later prosecution, the government must prove that every piece of evidence came from a source completely untainted by your immunized testimony.³

That burden is hard to meet in practice. Courts scrutinize the government’s evidence trail item by item. The theoretical door to prosecution stays open, which is why this form offers less protection than the alternative.

Transactional Immunity

Transactional immunity is the stronger version. A witness who receives it cannot be prosecuted at all for any offense related to what they testified about, no matter what independent evidence surfaces later. A document that turns up years afterward, completely unconnected to the testimony, still cannot be used to charge you.⁴

Federal law does not require transactional immunity, and federal prosecutors typically don’t offer it. Some states still grant it under their own statutes, so what you actually receive depends partly on which jurisdiction is running the investigation.

Informal or “Pocket” Immunity

Not every immunity deal runs through a court order. Prosecutors sometimes negotiate directly with a witness, usually in writing, in what is called pocket immunity or letter immunity. The agreement is between the prosecutor’s office and the witness, and it can offer transactional, use, or derivative use protection depending on what the prosecutor agrees to.

The key difference from a formal order is leverage. With informal immunity, the prosecutor cannot force an unwilling witness to testify, because there’s no court order to enforce. But the agreement still binds the prosecutor who made it. These deals come up often in cooperation negotiations, where a witness agrees to share information in return for a written promise not to prosecute.

What Immunity Does Not Protect You From

Even the broadest immunity has limits. Several kinds of legal exposure survive the grant.

Perjury and false statements. The federal immunity statute carves these out explicitly. If you lie under oath during immunized testimony, the lie itself is a separate crime you can be charged with, and the same goes for refusing to comply with the court’s order.¹
Future crimes. Immunity covers past conduct you testify about. It is not a license to commit new offenses afterward.
Civil lawsuits. Criminal immunity does not block a victim from suing you for damages. Criminal and civil proceedings run on separate tracks, and protection in one does not carry into the other.
Prosecution from an independent source. Under use and derivative use immunity, the government can still charge you for the same crime if it proves every piece of its evidence was gathered independently of your testimony.³

Does State Immunity Protect You From Federal Charges?

The Supreme Court addressed this in Murphy v. Waterfront Commission, holding that the Fifth Amendment protects a state witness against incrimination under federal law, and a federal witness against incrimination under state law. If a state compels your testimony under immunity, the federal government cannot use that compelled testimony or anything derived from it to prosecute you.⁵

The protection mirrors use and derivative use immunity rather than transactional immunity, which means another jurisdiction can still prosecute you if it develops its case through entirely independent evidence. In cases with both state and federal exposure, defense attorneys sometimes negotiate explicit cross-jurisdictional agreements to close that gap.

What Happens If You Refuse to Testify Anyway

Once the court issues an immunity order, your Fifth Amendment right to remain silent no longer covers the testimony it compels. Refusing is not a legal option. The court can hold you in civil contempt and order you confined until you agree to cooperate.¹

Federal law caps that confinement at 18 months or the life of the court proceeding or grand jury term, whichever is shorter. The moment you agree to testify, the confinement ends. If you hold out, you could spend up to a year and a half in custody without a conviction. It is coercive rather than punitive, designed to pressure compliance.⁶

Immunity Is Not a Cooperation Agreement

The two get confused, but they work differently. A cooperation agreement typically involves pleading guilty to a charge and then helping investigators in exchange for the prosecutor recommending a lighter sentence. You take a conviction and get credit for the cooperation. Immunity means no prosecution for the covered conduct and no guilty plea.

Prosecutors choose between the two based on the situation. If a witness’s own exposure is relatively minor and the information is valuable, immunity makes sense. If the witness is more deeply involved and the government wants some accountability on the record, a cooperation agreement with a reduced sentence is more likely. Which deal you’re offered, and the exact wording of it, can be the difference between walking away clean and carrying a criminal record, which is why anyone in these conversations should have a criminal defense attorney in the room.

1
Office of the Law Revision Counsel. 18 USC 6002 – Immunity Generally
2
Office of the Law Revision Counsel. 18 USC 6003 – Court and Grand Jury Proceedings
3
Justia. Kastigar v. United States, 406 US 441 (1972)
4
Legal Information Institute. US Constitution Annotated – Amdt5.4.5 Immunity
5
Justia. Murphy v. Waterfront Commission, 378 US 52 (1964)
6
Office of the Law Revision Counsel. 28 USC 1826 – Recalcitrant Witnesses