JM 9-90.550
The Counterintelligence and Export Control Section has jurisdiction over prosecutions under 2 U.S.C. § 192 in which witnesses have Communist Party or other subversive connections. Under the provisions of 2 U.S.C. § 194, contempt of Congress cases are referred directly by the Congress to the United States Attorney, by certification. If such a case is referred to a United States Attorney, in accordance with the JM 9-90.020 he or she should immediately notify the National Security Division, and no prosecution shall be initiated without prior authorization by the National Security Division.
[cited in JM 9-69.200]