Malloy v. Hogan
Because the Fifth Amendment protects people from giving self-incriminating evidence, state and federal courts sometimes trade immunity from prosecution for testimony that will help them convict offenders who are more detrimental to society. Rather than prosecute a prostitute, for instance, an agency may use testimony from a prostitute to break an entire prostitution ring. Transactional immunity, or full immunity, is one of the two kinds of prosecutorial immunity offered by state prosecutors to witnesses. Transactional immunity exempts witnesses not only from providing self-incriminating evidence, but also from being prosecuted for any wrongdoings admitted even when the prosecution obtains evidence outside of and not stemming from the witness's testimony. Although controversial, Congress passed a statute in 1893 that allowed transactional immunity in exchange for testimony and the Supreme Court sustained the statute by a 5-4 vote.
Use immunity, on the other hand, offers the same protection against any admittance of wrongdoing during the testimony. If, however, prosecutors obtain outside evidence outside of the scope of the testimony, they can still use it to prosecute a witness. Congress has found use immunity consistent with the Fifth Amendment. Congress also replaced all previous immunity statutes with a use-immunity statute. The Supreme Court agreed, arguing in 1972 that "[t]ransactional immunity . . . affords the witness considerably broader protection than does the Fifth Amendment privilege." Nevertheless, federal and state prosecutors continue to grant transactional immunity.