Legal Definitions - use/derivative-use immunity

Use/Derivative-Use Immunity is a legal protection granted to a witness who is compelled to provide testimony, often under a subpoena, despite their Fifth Amendment right against self-incrimination. This immunity means that the specific statements made by the witness, and any evidence *directly or indirectly obtained* or discovered as a result of those statements (known as "derivative use"), cannot be used by the government to prosecute that witness for a crime.

However, it is crucial to understand that use/derivative-use immunity does not provide absolute protection from prosecution. The witness can still be prosecuted for the same crime if the prosecution can gather entirely *independent evidence* of their guilt—meaning evidence that was discovered without any reliance on the compelled testimony or any leads generated from it. This differs from "transactional immunity," which offers broader protection by preventing prosecution for the entire transaction or event about which the witness testified, regardless of independent evidence.

Here are some examples to illustrate this concept:

• Example 1: Corporate Whistleblower

  Imagine a senior accountant, Sarah, is subpoenaed to testify before a grand jury investigating financial fraud at her company. Sarah knows details that could implicate her, so she invokes her Fifth Amendment right. To compel her testimony, the prosecutor grants her use/derivative-use immunity. Sarah then testifies, admitting to knowledge of certain accounting irregularities and the methods used to conceal them, including some actions she took under duress.

  How it illustrates the term: Sarah's specific testimony about her actions and knowledge cannot be used against her in a future criminal trial. Furthermore, if her testimony leads investigators to discover a hidden ledger, that ledger also cannot be used against her because it is "derivative use" evidence. However, if the prosecution had *already* independently obtained emails and bank records through a separate investigation that clearly show Sarah's direct involvement in the fraud, they could still use *that independent evidence* to charge and prosecute her.

• Example 2: Witness to a Street Crime

  David witnesses a violent assault and is subpoenaed to testify. He is reluctant because he was also involved in a minor, unrelated public disturbance at the scene and fears self-incrimination. The court grants him use/derivative-use immunity to compel his testimony about the assault. During his testimony, he briefly mentions his presence during the public disturbance.

  How it illustrates the term: David's testimony about the assault, and his admission about being present during the public disturbance, cannot be used to prosecute him for that disturbance. If, however, the police had *already* obtained surveillance footage from a nearby store showing David actively participating in the public disturbance *before* he testified, they could still use that independent footage as evidence to prosecute him for the disturbance.

• Example 3: Drug Trafficking Investigation

  A low-level member of a drug trafficking organization, Mark, is arrested. Prosecutors believe he has crucial information about the higher-ups but needs to compel his testimony. They offer him use/derivative-use immunity. Mark agrees and provides detailed testimony about the organization's structure, drug routes, and the roles of various members, including some limited admissions about his own involvement.

  How it illustrates the term: The government cannot use Mark's specific testimony, or any evidence directly uncovered because of his testimony (e.g., a specific stash house he mentioned), to prosecute him. However, if federal agents had been tracking Mark for months through independent informants, wiretaps, and surveillance, and had already gathered sufficient evidence of his involvement *prior to and independent of* his immunized testimony, they could still pursue charges against him based on that pre-existing, independent evidence.