The Supreme Court has held that in a grand jury setting, a newsman's status is the same as that of any other citizen and therefore he must respond to subpoena and answer all relevant questions relating to any investigation into the commission of crime.
Branzburg v. Hayes, 408 U.S. 665 (1972).
Ronald C. Weingrad,
Constitutional Law - First Amendment - Right of Newsmen Not to Reveal Confidential Sources of Information to a Grand Jury,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol11/iss4/9