There are situations in which the prosecution can’t offer a witness immunity from prosecution, and others in which a grant of immunity is limited.
Prosecutors typically don’t offer dangerous sex offenders immunity because of the state’s paramount interest in prosecuting violent sex crimes. Additionally, any crimes the witness commits while testifying, or crimes that otherwise impede the investigation and prosecution of a case, may be prosecuted, including:
But even a witness who commits one of these crimes after a grant of immunity won’t lose that immunity as it relates to the criminal activity the witness testified about.
For example, suppose that the prosecution gives Witness transactional immunity from prosecution for his role in a drug distribution ring. Witness testifies that he and Defendant sold cocaine, but no other drugs, and that he and Defendant were the only people who imported and sold the cocaine. After Witness’s testimony, the prosecution learns that Witness and Defendant sold marijuana in addition to cocaine, and that Witness’s wife also imported and sold cocaine and other drugs.
Can Witness be successfully prosecuted for perjury? Yes. Witness testified that he and Defendant alone imported and sold cocaine only. The statement was false.
Can Witness be successfully prosecuted for obstruction of justice? Yes. Witness tried to hide the fact that his wife was also culpable, which obstructs the prosecution’s goal of finding out the truth about the drug ring.
Can Witness be successfully prosecuted for selling cocaine? For selling marijuana? Witness is safe when it comes to the cocaine offense(s). He received transactional immunity and therefore can’t be prosecuted for any criminal activity revealed in his immunized testimony. But he didn't reveal the marijuana activity in that testimony, so the prosecution is free to charge him with it.
In some instances, more than one jurisdiction—for example, both the state and federal government or more than one state—can prosecute a crime. An example is a major drug distribution operation that violates both state and federal laws. So, what happens when a witness is offered immunity in one jurisdiction, but not another?
Federal and state prosecutors can’t use testimony compelled by the other jurisdiction. This means that a federal prosecutor can’t use a witness’s immunized state testimony, and vice versa.
A witness who receives transactional immunity in one city, county, or state can’t be prosecuted in another city, county, or state. In other words, the immunity from prosecution extends from one jurisdiction to another within the state.
The federal system offers use and derivative use immunity, but not transactional immunity. This means that a witness who receives transactional immunity from a state prosecutor could potentially be prosecuted for activities relating to the witness’s testimony that are illegal under federal law. However, a federal prosecutor cannot use the witness's testimony against him or her.
Suppose that Witness receives transactional immunity from a state prosecutor in New York in exchange for testifying about his role in a series of bank robberies. During his testimony, Witness talks about crimes he committed in New Jersey, as well as activities that might be illegal under federal law.
Can Witness be successfully prosecuted in New Jersey for the crimes he discussed? No. Transactional immunity agreements must be followed by all states. Because Witness had transactional immunity from the State of New York, he is protected from prosecution by any other state.
Can Witness be successfully prosecuted in federal court for the crimes he discussed? Yes. Transactional immunity doesn’t extend to federal prosecutions, so Witness could potentially be prosecuted for his federal crimes. However, a federal prosecutor may not use Witness’s own words against him.
If you’ve been asked to or think you should testify or otherwise cooperate with the authorities, consult an experienced criminal defense lawyer. Only such a lawyer can explain the ins and outs of immunity and otherwise protect your rights.