The Sergeant at Arms and Doorkeeper of the Senate is the law enforcer for the United States Senate. One of the chief roles of the Sergeant is to hold the gavel used at every session. The Sergeant can also request the attendance of absent Senators.
With the Architect of the Capitol and the House Sergeant at Arms, he serves on the Capitol Police Board, responsible for security around the building.
The Sergeant at Arms of the Senate can arrest any person upon their violating Senate rules (including the President of the United States upon orders from the Senate).