With Congress poised to vote on the so-called nuclear option, one fact has been largely lost amid the debate: Restrictions on the use of filibusters are already in place on a host of matters, from budgets to resolutions granting war powers to the president.
Obviously, the question on the floor this week - judicial appointments - is unique. Democrats are eager to preserve their current ability to stall a vote, especially on nominees to the Supreme Court. And Republicans are just as eager to change the rules so that 51 Senators, rather than 60, can end debate on a nominee.
But the fight over judges is hardly as pure a contest over Senate traditions as many people believe. The use of filibusters to prolong debate, though revered by many as a tool for the Senate minority, has been progressively curtailed in recent years on a host of important issues.
One key reason: A rising belief in official Washington that the only way to get contentious legislation out of Congress is to rein in debate and amendment. The restrictions are also, in part, a holdover from the early 1970s, when a Democratic Congress sought to bolster the power of the legislative branch clout against an "imperial" (and Republican) presidency.
"When we talk about 'unlimited debate' in the Senate, we've already limited that unlimited debate over the last 30 years in a major way," says former Senate parliamentarian Robert Dove, now a professor at George Washington University. "We have on the books probably a couple of hundred laws that set up specific legislative vehicles that cannot be filibustered or only amended in a very restricted way."
Consider some big-ticket items now before Congress on which lawmakers have given up their rights to filibuster.
• The Pentagon's 2006 Base Realignment and Closure plan, which proposes closing 180 sites.
• The pending Central American Free Trade Agreement.
• President Bush's proposed $70 billion in tax cuts and $35 billion in mandatory spending cuts, protected by budget reconciliation.
• Drilling in the Arctic Regional Wildlife Refuge. The years-long effort by Republicans to pass this legislation may finally succeed this year, because this time it is protected from filibuster as part of the budget reconciliation.
The first curbs on extended debate came in 1917, after Congress refused to move to a vote on President Wilson's request to arm the merchant marine. Much of the impetus to rein in the filibuster in the 1960s and '70s came from liberal Democrats, whose main experience with extended debate had been as a hammer by conservative southerners to stop civil rights legislation.
"In the 1960s the word filibuster only meant one thing in the Senate, with very few exceptions," explains Mr. Dove. "Successful filibusters were filibusters against civil rights legislation. And if you were going to create an atmosphere in which civil rights legislation would get through more easily, you needed to change the cloture rule" - the votes needed to end debate.
In 1975, the Senate, led by liberal Democrats, lowered the bar to end debate again, from two-thirds of those present and voting (as many as 67 votes) to 60 votes. Tuesday's expected move, led by GOP conservative, would lower the bar for judicial nominations to a simple majority.
"We're in a year of romanticizing the filibuster, but it's important to remember there has often been a dislike of that tool," says Julian Zelizer, a congressional historian at Boston University.
In addition to periodically changing its rules for ending debate, Congress has written curbs on extended debate or amendment into specific laws in a bid to make the legislative process more efficient.
Laws that restrict debate include: the War Powers Act, the Budget Act of 1974, the Trade Act of 1974 (and subsequent "fast track" votes on trade), arms export controls, Federal Election Commission regulations, the Alaska Natural Gas Transportation Act of 1976, the Nuclear Waste Policy Act of 1982 (including the choice of Yucca Mountain as a national waste-disposal site), the 1991 act governing military-base closings, US participation in the World Trade Organization, and the Andean Counterdrug Initiative.
In between negotiating sessions with other moderates over how to avoid changing the filibuster rule, Sen. Susan Collins (R) of Maine has also been worrying about the blow her state is taking from a new round of proposed military-base closings. Earlier this month, the Pentagon proposed closing the Portsmouth Naval Shipyard in Kittery as well as massive downsizing for the Brunswick Naval Air Station, among 180 sites nationwide.
"It's my top priority," she says. "The nation can't have all our bases in the South and Southwest." Yet base closings are one of the many areas where Congress has already waived its right to filibuster or even amend the list, once it is finalized by a base-closing commission.
Congress, essentially, has come to realize that some issues are so thorny that the normal congressional process doesn't work. Base closings is such an issue, given that few lawmakers will support shutting bases in their own districts.
Republicans leaders say the same principle applies this week. "We limited the filibuster when the Budget Act was passed, and the dome of the Capitol didn't crumble," says Bob Stevenson, a spokesman for Senate majority leader Bill Frist.
But critics say there's an important distinction: Today's sharp party split. "If you look at these areas that limit the filibuster individually, they had broad bipartisan support," says Ross Baker, a political scientist at Rutgers University in New Brunswick, N.J. "This is a change that's being forced through on very narrow, partisan support, and that's a big difference."