Rule 5Senate Rules on Impeachment Trials, Rule V

The Senate shall have power to compel the attendance of witnesses, to enforce obedience to its orders, mandates, writs, and judgments, to preserve order, and to punish in a summary way contempts of, and disobedience to, its authority, orders, mandates, writs, or judgments, and to make all lawful orders, rules, and regulations which it may deem essential or conducive to the ends of justice. And the Sergeant-at-Arms of the Senate, under the direction of the President of the Senate, may employ such aid and assistance as may be necessary to enforce, execute, and carry into effect the lawful orders, mandates, and writs of the Senate.