Privilege against Self-Incrimination
A witness may refuse to answer questions or give documentary evidence only if the answer or document would incriminate the witness. An answer is considered self-incriminating if it would lead to criminal liability in any jurisdiction. The answer need only furnish a link in the chain of CIRCUMSTANTIAL EVIDENCE necessary for a conviction Blau v. United States, 340 U.S. 159, 71 S. Ct. 223, 95 L. Ed. 170 (1950). The answer does not have to be one that would be admissible as evidence in a criminal trial.
The privilege does not allow a witness to refuse to answer a question because the response may expose the witness to civil liability, social disgrace, loss of status, or loss of private employment. A witness may not claim the privilege on the grounds that an answer or document may incriminate a third party: it may be declared only by the witness for the witness.
In some criminal cases, a prosecutor may grant to a witness IMMUNITY from prosecution. This immunity comes in two forms: transactional and testimonial. Transactional immunity gives the witness immunity from prosecution for the criminal acts to which the witness refers in his or her statements. Testimonial immunity merely prevents the prosecution from using the statements the witness makes in a subsequent prosecution of the witness. Prosecutors have the right to grant only testimonial immunity and thereby force witnesses to testify. If the witness refuses to testify after being given testimonial immunity, he or she could be jailed for CONTEMPT of court. Furthermore, if a witness with testimonial immunity testifies falsely, the false statements may be used against the witness in a subsequent prosecution for perjury.
By contrast, if police or prosecutors summon a witness to produce self-incriminating documents, the witness may claim the privilege because a summons to produce documents is similar to a demand for testimony. Curcio v. United States, 354 U.S. 118, 77 S. Ct. 1145, 1 L. Ed. 2d 1225 (1952). However, police and prosecutors may force a witness to relinquish self-incriminating documents if the records pertain to a regulated public matter, such as price records kept by businesses under price regulation statutes.