The Federal Rules of Civil Procedure apply to court proceedings to enforce an agency to compel testimony or production of documents through a subpoena issued under any federal statute, except as otherwise provided by statute, court rules, or court order in the proceedings[i].
Likewise, if a particular regulatory statute contains no provision that deals with the procedure to be followed in an enforcement proceeding, then the procedures specified in the Federal Rules of Civil Procedure will be followed.
A court will not permit its process to be abused. Such an abuse will take place if the summons is issued for an improper purpose, such as to harass a person or to put pressure on him/her to settle a collateral dispute, or for any other purpose reflecting on the good faith of the particular investigation[ii].
An enforcement procedure can be commenced by motion or order to show cause. It is to be noted that a formal complaint is not required.
[i] USCS Fed Rules Civ Proc R 81
[ii] United States v. Powell, 379 U.S. 48 (U.S. 1964)