Kastigar v. United States is a significant Supreme Court case that addressed the balance between self-incrimination rights and the government's ability to compel testimony in grand jury proceedings. Decided by a 5-2 majority, the Court upheld a 1970 law that allowed for the granting of use immunity to witnesses. Under use immunity, individuals can be compelled to testify without the government being able to use that testimony against them in future prosecutions. This decision was rooted in the Court's interpretation of the Fifth Amendment, which protects against self-incrimination, determining that use immunity sufficed, contrary to claims that transactional immunity—covering all offenses related to the testimony—was necessary for adequate protection. The ruling had a profound impact on prosecutorial practices, leading to a notable increase in the use of grants of use immunity during grand jury investigations. Kastigar v. United States thus serves as a focal point in discussions about legal protections for witnesses and the powers of the state in gathering evidence.