It easily has the power to block the governor's appointment of Roland Burris.

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.

Powell also said that each house could "judge" the qualifications laid out in the Constitution (such as age) but could not make up new qualifications. Thus, if the Senate were to plausibly decide in good faith that a candidate failed to meet the Constitution's age requirement, Powell nowhere suggests that this senatorial determination should be set aside by ordinary federal courts. For similar reasons, federal courts should not interfere when the Senate plausibly and in good faith decides an election or return to be improper or corrupt. The critical point here is that the Constitution itself sets up the Senate as the highest court of Senate elections. When the Senate speaks as this court, its adjudications are legal judgments that no other court may properly reopen. If the Senate convicts a federal judge in an impeachment court, no other federal court may properly interfere. So, too, for Senate elections and returns.

What are the counterarguments in favor of seating Burris? Both he and Blagojevich say that the Senate should not hold the governor's sins against his would-be senator. To be sure, there is no evidence Burris bribed the governor to get this seat. But imagine if Burris had won election only because other candidates were wrongly and corruptly kept off the ballot. Surely the Senate could properly deem this an invalid election. Similarly, it now seems apparent that there were candidates that Blagojevich refused to consider for improper reasons—because one refused to "pay to play" early on, or because another is at the center of the impending criminal case against the governor. With the appointments process so inherently and irremediably tainted, the Senate may properly decide that nothing good can come from a Blagojevich appointment.

(And let's not feel too sorry for Burris, who, after all, has shown dubious judgment in accepting the nomination, given the circumstances. Weeks ago, Senate leaders announced that no Blagojevich appointee would be allowed to sit. What is Burris thinking? Many other ­arguably better ­candidates doubtless refused to have any dealings with Blagojevich once his crimes came to light; Burris got his shot at the Senate at their expense.)

Nor does it matter, from the Senate's point of view, that Blagojevich hasn't yet been convicted. In this context, the Senate itself is a judge, in the words of the Constitution, and can decide facts for itself. It need not follow the rules of criminal courts. That means it need not find Blagojevich guilty beyond reasonable doubt, as a court would if his liberty were in jeopardy. It is enough for the Senate to reject Blagojevich's appointee if a majority of senators are firmly convinced that Blagojevich is corrupt and that any nomination he might make is inherently tainted by such corruption.

To make sure its ruling sticks, the Senate should follow its own procedures with due deliberation. Burris' case can be referred to a committee for careful review. He need not be seated while this committee does its work, and it will be very hard for Burris to persuade any federal judge to interfere in the meantime, especially if Senate Democrats and Republicans unite. With any luck, Blagojevich will be out of office soon enough and a new appointments process (or a special election) can begin that would supersede the attempted Burris appointment.

Finally, the Senate can bulletproof its vote to exclude Burris by adopting an anticipatory "sense of the Senate" resolution declaring that if Burris were ever to take the matter to a federal court and prevail, the Senate would immediately expel him. Expulsion would ultimately require a two-thirds vote. If two-thirds of the Senate is ready to vote against Burris now, an anticipatory resolution would discourage him from going to court in the first place. It would also discourage any activist judges who might be tempted by his case. Whether to seat Burris is the Senate's call: It easily has the brute power—and the constitutional right—to stop Blagojevich.