Article I Section 6 Clauses 1 and 2

[1] The Senators and Representatives shall receive a Compensation for their Services, to be ascertained by Law, and paid out of the Treasury of the United States. They shall in all Cases, except Treason, Felony and Breach of the Peace, be privileged from Arrest during their Attendance at the Session of their respective Houses, and in going to and returning from the same; and for any Speech or Debate in either House, they shall not be questioned in any other Place.

[2] No Senator or Representative shall, during the Time for which he was elected, be appointed to any civil Office under the Authority of the United States which shall have been created, or the Emoluments whereof shall have been increased during such time; and no Person holding any Office under the United States, shall be a Member of either House during his Continuance in Office.

Members of congress get paid from the U.S. Treasury and get to vote for there own salaries. A fairly stupid setup if you ask me, but I was not at the convention when this was getting put down on paper.

Salaries of Members of Congress, 1789-2006 (from here pdf)
Payable Salary Effective Date

$1,500 March 4, 1789

$1,500 March 4, 1795

$1,500 March 3, 1796

$1,500 December 4, 1815

$1,500 March 3, 1817

$2,000 March 3, 1817

$3,000 December 3, 1855

$3,000 December 23, 1857

$5,000 December 4, 1865

$7,500 March 4, 1871

$5,000 January 20, 1874

$7,500 March 4, 1907

$10,000 March 4, 1925

$9,000 July 1, 1932

$8,500 April 1, 1933

$9,000 February 1, 1934

$9,500 July 1, 1934

$10,000 April 4, 1935

$12,500 January 3, 1947

$22,500 March 1, 1955

$30,000 January 3, 1965

$42,500 March 1, 1969

$44,600 October 1, 1975

$57,500 March 1, 1977

$60,662.50 October 1, 1979

$69,800 December 18, 1982, for Representatives July 1, 1983, for Senators

$72,600 January 1, 1984

$75,100 January 1, 1985

$77,400 January 1, 1987

$89,500 February 4, 1987

$96,600 (Representatives) February 1, 1990

$98,400 (Senators) February 1, 1990

$125,100 (Representatives) January 1, 1991

$101,900 (Senators) January 1, 1991

$125,100 (Senators) August 14, 1991

$129,500 (Reps. and Sens.) January 1, 1992

$133,600 (Reps. and Sens.) January 1, 1993

$136,700 (Reps. and Sens.) January 1, 1998

$141,300 (Reps. and Sens.) January 1, 2000

$145,100 (Reps. and Sens.) January 1, 2001

$150,000 (Reps. and Sens.) January 1, 2002

$154,700 (Reps. and Sens.) January 1, 2003

$158,100 (Reps. and Sens.) January 1, 2004

$162,100 (Reps. and Sens.) January 1, 2005

$165,200 (Reps. and Sens.) January 1, 2006

However we are lucky as the 27th amendment (ratified in 1992) made it so that the pay raise takes place only after the next election. This (in theory) gives us, the poor voters, the ability to vote anyone out of office we feel may be giving themselves a bit too much money. However because most people don’t pay a lick of attention to what the people who lead them do, this rarely if ever happens.

This part of the Constitution also protects legislators from arrests in civil lawsuits while they are in session, they may however be arrested in criminal matters. Congress members are granted immunity from lawsuits for the things they say and do as legislators. While this allows them to make statements without the fear of a libel or slander lawsuit it also lets them get away with saying some of the dumbest shit.

“There is no one person in the Bush administration who is indispensable — with the exception of the president,” Rick Santorum

“The Internet is not a big truck…it’s ah, ah, it’s a series of tubes!” Ted Stevens

We the voters are supposed to serve as the check on this branch of government. We are supposed to be watching what they say, and if its a crock, voting them out of office.

To ensure the separation of powers between the three branches, senators and representatives are prohibited from holding any other federal office during their service in Congress. They are however allowed to run for another office (say run for president while you are a senator) and simply step down from being a congressperson if they get the new job.