The Federal Bureau of Investigation’s Domestic Investigations and Operations Guide, the bible for agents, has long recognized that journalists, the clergy and lawyers deserve special protections because of the constitutional implications of investigating their work. Penitents who confess to a priest, sources who provide confidential information to a reporter, and clients who seek advice from counsel are assumed to be protected by a high bar of privacy, which must be weighed against the state’s interests in investigating matters or subpoenaing records. Judges and members of Congress also fall into a special FBI category...