Does the Constitution allow the Senate to refuse to seat Roland Burris, Illinois Gov. Rod Blagojevich's surprise appointee? In a word, yes. Here's why.
Following English parliamentary tradition and early Colonial and state practice, the framers made the Senate its own gatekeeper and guardian. Each house of Congress is "the Judge of the Elections, Returns, and Qualifications of its own members," according to Article 1, Section 5 of the Constitution. At the founding, Senators were elected by state legislatures. If the Senate believed that legislators in a given state had been bribed into voting for a particular candidate, the Senate could refuse to seat him.
Because of the word "returns" in Section 5, what is true of elected Senators is equally true of appointed Senators. According to the Oxford English Dictionary, a "Return" in the time of the framers involved a report of an appointment made by a sheriff or other official. If the Senate may refuse to seat a person picked in a corrupt election, it likewise may refuse to seat a person picked in a corrupt appointment process. (Alternatively, we might think of an appointment as an "election" by one voter.)
A simple majority of the Senate would suffice to exclude Burris. Majority rule is the general default principle established by the Constitution, except where text, structure, or tradition indicates otherwise. When the Senate tries to expel a member who has already been seated, the rule is two-thirds (as it is when the Senate sits as an impeachment court). But the framers clearly understood that majority rule would apply when the Senate was judging the accuracy and fairness of elections or appointments.
The power to judge elections and returns has been used on countless occasions in American history, at both the state and federal level, to exclude candidates whose elections and appointments were suspect.
True, in the 1969 case of Powell v. McCormack, the Supreme Court properly held that the Constitution imposes limits on the power of the Senate and the House to exclude members. Some legal commentators say this decision trumps the Senate's power to exclude Burris. But the letter and spirit of Powell actually cut against him. The case involved an elected congressman, Adam Clayton Powell, whom the voters had clearly chosen in a fair election and whom the House nevertheless excluded—wrongly, the court held. The key fact is that there was no doubt whatsoever that Powell was the people's choice, and in issuing its ruling, the Warren Court repeatedly stressed this. The justices insisted that their ruling was aimed at protecting the people's right to vote. None of that spirit applies here. And that's why the case doesn't stand in the Senate's way now.