The constitutional argument advanced by Senate Republican supporters of the so-called "nuclear option" to end Democratic filibusters of President Bush’s judicial nominees — which is that any nominee who has majority support must be confirmed — is weak.

So is the constitutional argument advanced by Senate Democrats, which is that the Senate cannot amend its own filibuster rule (Rule 22), ever, by less than a two-thirds vote.

The ultimate question is hard. Both sides have strong arguments as well as weak ones. And the stakes — for the future of the Senate, the judiciary, the presidency, and constitutional government itself — are extraordinarily high.

Some background: Since 2001, Senate Democrats have accused President Bush of seeking to pack the courts with radical conservatives bent on junking decades of Supreme Court precedent. And since 2003, the Democrats have responded by making all-but-unprecedented use of the filibuster to block floor votes on Bush’s 10 most controversial appeals court nominees. These 10 (some of whom were not so radical) had majority support, but not the 60 votes required by Rule 22 to break a filibuster. Bush has renominated seven of them.

Senate Majority Leader Bill Frist and other Republicans want to bar filibusters of judicial nominees by amending Rule 22. Since that rule specifies that it can be amended only by a two-thirds majority, Frist plans a complex parliamentary maneuver:

Vice President Cheney, as president of the Senate, would uphold a point of order holding that the Constitution either: 1) bars use of the filibuster to stop nominees; or 2) empowers a 51-vote majority to amend the Senate rules to bar such filibusters. (Or both.) Cheney’s ruling would stand unless rejected by 51 senators, including at least six of the 55 Republicans. This would clear the way for party-line votes to confirm all pending Bush nominees and, probably, any and all Bush Supreme Court nominees.

It would also mean civil war in the Senate. Democratic Leader Harry Reid warned on March 15 that Democrats would use parliamentary tactics to bring to a halt all Senate business excepting "legislation vital to our troops or other national security interests" and "critical government services."

Both Republicans and Democrats claim that the Constitution is on their side. Both are wrong.

Frist claims that the Constitution’s "advice and consent" clause requires Senate confirmation of any nominee who has majority support. This argument rests on the notion that by explicitly requiring supermajority votes for some purposes, such as ratifying treaties, the Constitution implies that a simple majority vote must suffice to confirm a nominee.

But the same logic suggests that a simple majority vote must suffice to pass a law. And the constitutional power of each chamber to set its own rules has long been interpreted to allow majority-supported legislative proposals and nominees alike to be buried in committee, stalled by individual "holds," filibustered, or otherwise prevented from coming to a vote.

Frist does not question the Rule 22 right to filibuster legislative proposals, which has been cherished by Republicans even more than by Democrats. He distinguishes the same Rule 22’s right to filibuster nominations as interfering with the president’s power to staff the judiciary. But this distinction is untenable under a Constitution that gives the Senate an absolute veto over presidential nominees.

Nor is the judiciary in any danger of not being staffed. The Senate confirmed 204 of Bush’s first-term judicial nominees, including 35 appeals court nominees, leaving the federal courts with relatively few vacancies by historical standards.

Frist also stresses that filibusters have not traditionally been used (with a few arguable exceptions) to kill majority-supported nominations, in part because there is no way to compromise or amend a nominee. True. But this hardly warrants Frist’s conclusion that the Constitution bans judicial filibusters while smiling on legislative filibusters.

Indeed, Frist himself voted in 2000 to sustain a filibuster of a Clinton nominee, as did many other Republicans. But neither side has clean hands in this: Many of the same Democrats who have filibustered Bush nominees once assailed Republicans for using the same tactic.

Republicans are on much firmer ground in attacking Rule 22’s requirement of a two-thirds vote to change the rule itself, or any other Senate rule. The same constitutional provision that authorizes each chamber to "determine the rules of its proceedings" also authorizes each chamber to expel a member — while requiring a two-thirds vote to do the latter but not the former. The unmistakable implication is that a simple majority can change the rules.

Democrats argue that the Senate is a "continuing body," because only one-third of its members face the voters every two years. This, they say, means that the Senate’s rules automatically continue from one Congress to the next, ad infinitum. But it is impossible to believe that the Framers intended that one group of senators could bind all of their successors, to the end of time, by requiring an in-practice-unattainable supermajority vote to change a rule. Otherwise, the Senate could impose a permanent requirement of, say, 100 votes to limit Social Security benefits. Or to raise taxes.

Democrats make a more plausible case that the Republicans have in effect waived any right to go nuclear during the current Congress, because they have so far treated the previous rules as continuing. But I am not quite persuaded on that.

So in my view, Senate Republicans have the raw constitutional power to bulldoze filibusters of nominees. They also have a point in complaining that the Democrats’ use of the filibuster represents a major escalation of the unending brawl over judicial appointments.

To be sure, a Republican filibuster helped kill President’s Johnson’s nomination of Supreme Court Justice Abe Fortas to be chief justice. But it was unclear whether the scandal-plagued, rapidly sinking Fortas had majority support. Republicans also filibustered two Clinton judicial nominees, but both were eventually confirmed. And when in the majority, from 1995 to 2000, Republicans used their control of the Senate to kill many majority-supported Clinton nominations by denying them hearings and using anonymous "holds" and other parliamentary tactics. Democrats had previously done the same to many George H.W. Bush nominees.

Both sides share blame for this downward spiral of partisan bitterness. But it is the Democratic filibusters — together with Bush’s insistence on total victory — that have brought the process to the brink of total war. And unless six or more Republicans show more restraint than anyone else has shown, the war will come.

This war would not only make the Senate an exceedingly unpleasant place to be. It would also make it more like the House, where narrow majorities cemented by iron party discipline habitually use raw power to impose their will.

This would be "too high a price to pay in order to stop Senate Democrats’ abuse of the filibuster," former Republican Sens. Jim McClure of Idaho and Malcolm Wallop of Wyoming suggested in a Wall Street Journal op-ed. They also stressed that "it is naive to think that what is done to the judicial filibuster will not later be done to its legislative counterpart, whether by a majority leader named Reid, or Clinton, or Kennedy," and that this would remove "our only defense against the excesses of a bipartisan liberalism."

McClure and Wallop are right. At least as long as the stakes are relatively low — the fate of a handful of lower-court nominees — the nuclear option is too drastic a remedy for the Democrats’ brinksmanship. In the words of the late constitutional scholar Charles Black, "Unrestricted debate in the Senate is the only check upon president and party autocracy."

Except, that is, for the judiciary itself, which is ultimately to blame for the escalating hostilities over judicial appointments. The Supreme Court has vitiated its role as a check upon majoritarian abuse — and has transformed the judicial appointment process into a perpetual battle over a wide range of the nation’s most divisive issues — by giving itself a blank check to legislate its own policy preferences (some of which I share) on those issues. They range from abortion, the death penalty, and religion, to state sovereign immunity.

But we still need the judiciary, as well as the Senate, as a check upon majoritarian autocracy. Imagine a world in which the president could order you or me seized from our homes, branded "enemy combatants," and held incommunicado, for as long as he chooses, with no access to a lawyer or judge, ever. That is the world in which we would now be living had not eight aging justices rebuffed Bush’s bid for such autocratic power last June. And that is the world in which we might eventually find ourselves if the Senate transforms itself into a rubber stamp.