The letter of authority specifically extends the authorization to compel the witness to testify to any ancillary proceeding. This is intended to cover the witness's testimony at a trial or trials following his or her immunized testimony before a grand jury, thus avoiding the necessity of a second application. Authority to compel a witness to testify before a grand jury must be renewed, however, if the witness has not testified within six months of the date of the letter of authority. A new application is necessary in order to ensure that the decision to grant the witness immunity is still in the public interest.
Updated June 9, 2015