In 1807 in Burr's Trial73 Chief Justice Marshall lays down the broad doctrine which has been generally acquiesced in, that where the witness avers under oath that the answer to the question which has been propounded to him will tend to incriminate him, no other testimony may be demanded by the court as to this fact. "If the question be of such a description that an answer to it may or may not incriminate the witness, according to the purport of that answer, it must rest with himself, who alone can tell what it would be, to answer the question or not,"

The fact that the immunity from prosecution afforded by a federal statute gives the witness no security from prosecution in the state courts as to matters regarding which he is asked to testify, is immaterial.74