Senate Rule VI - Quorum - absent senators may be sent for

111th Congress
1. A quorum shall consist of a majority of the Senators duly chosen and sworn. 2. No Senator shall absent himself from the service of the Senate without leave. 3. If, at any time during the daily sessions of the Senate, a question shall be raised by any Senator as to the presence of a quorum, the Presiding Officer shall forthwith direct the Secretary to call the roll and shall announce the result, and these proceedings shall be without debate. 4. Whenever upon such roll call it shall be ascertained that a quorum is not present, a majority of the Senators present may direct the Sergeant at Arms to request, and, when necessary, to compel the attendance of the absent Senators, which order shall be determined without debate; and pending its execution, and until a quorum shall be present, no debate nor motion, except to adjourn, or to recess pursuant to a previous order entered by unanimous consent, shall be in order.

109th Congress

 * 1. A quorum shall consist of a majority of the Senators duly chosen and sworn.
 * 2. No Senator shall absent himself from the service of the Senate without leave.
 * 3. If, at any time during the daily sessions of the Senate, a question shall be raised by any Senator as to the presence of a quorum, the Presiding Officer shall forthwith direct the Secretary to call the roll and shall announce the result, and these proceedings shall be without debate.
 * 4. Whenever upon such roll call it shall be ascertained that a quorum is not present, a majority of the Senators present may direct the Sergeant at Arms to request, and, when necessary, to compel the attendance of the absent Senators, which order shall be determined without debate; and pending its execution, and until a quorum shall be present, no debate nor motion, except to adjourn, or to recess pursuant to a previous order entered by unanimous consent, shall be in order.

Resources

 * Rules of the 109th U.S. Senate

Articles

 * "Rule VI," U.S. Senate - Committee on Rules and Administration, 2005.