[citation needed] In the United States, Congress can also grant criminal immunity (at the Federal level) to witnesses in exchange for testifying.
The grant of immunity impairs the witness's right to invoke the Fifth Amendment protection against self-incrimination as a legal basis for refusing to testify.
§ 6002, a witness who has been granted immunity but refuses to offer testimony to a federal grand jury may be held in contempt.
In addition, grand jury witnesses may be prosecuted for perjury or making false statements in their testimony.
In Kastigar v. United States, 406 U.S. 441 (1972), the US Supreme Court confronted the issue of the type of immunity, use or transactional, constitutionally required to compel testimony.