The filibuster has undergone a fundamental change since Frank Capra’s classic film “Mr. Smith Goes to Washington” celebrated the tactic in 1939. Back then it was a rare effort by outnumbered lawmakers — or even a single senator fighting a lonely battle, a la Jimmy Stewart’s Jefferson Smith — to derail a bill. Now it’s a routine, even daily, practice by the Senate minority to block bills, stymie nominees and squeeze more concessions out of the majority.

The shift has persuaded even Common Cause, an erstwhile defender of the filibuster, to shift sides and question its constitutionality. The group plans to mount a court challenge against the filibuster rule on the grounds that it effectively superecedes the constitutional requirement that most bills pass on a simple majority vote. We’re sympathetic to that argument, but not sanguine about the group’s prospects. Instead, we urge lawmakers to take matters into their own hands and restore majority rule in Congress.

Technically speaking, a filibuster happens when one side refuses to stop talking and start voting. This kind of obstructionism wasn’t possible when the Founders drew up the Constitution. According to a Common Cause brief, Congress initially allowed both chambers to end debate by a majority vote, and senators invoked this power 10 times in their first nine two-year sessions. But the Senate changed its rules in 1806 to eliminate members’ ability to cut off debate, apparently in an effort to streamline and simplify their procedures. Thus were filibusters born, although they were rarely attempted in the 1800s. The Senate in 1917 adopted a rule under which “cloture” could be invoked by a supermajority vote to limit debate, but filibusters remained so unusual that the cloture was adopted less than twice annually on average for the next 50 years.

The tactic gained popularity during the epic debates over civil rights legislation in the mid-20th century, and threatened or actual filibusters prompted Senate leaders to file about 20 cloture motions per year in the 1970s and 1980s. Cloture motions jumped again in the 1990s in response to filibusters by both Republicans (during the first years of the Clinton presidency) and Democrats (after the GOP gained control of the Senate in 1995). Ever since Democrats regained control of the Senate in 2007, however, filibusters have occurred with numbing frequency. Nearly 139 cloture motions were filed during the 2007-08 session of Congress, and even more are expected in the current session.

No longer does a filibuster involve a senator standing for hours on end, reading volumes of extraneous material and refusing to give up the floor as Jefferson Smith memorably did. Now it’s simply a party leader refusing to allow a bill to be brought up by unanimous consent, forcing bill supporters to round up a three-fifths majority — or 60 votes — in support of a cloture motion just to end debate on the motion to begin debating. Nor do senators who want to filibuster a bill have to worry about bringing all Senate business to a grinding halt until the dispute is resolved. Thanks to a rule change in the mid-1970s, when the minority signals its intent to filibuster a bill, the Senate can set the measure aside and proceed to something else.

The result is that legislating in the Senate, which has never been speedy, has become a drawn-out exercise in brinksmanship and unseemly horse-trading. The supermajority requirement gives members of both parties more leverage to extract promises of special treatment for their states, as Sens. Ben Nelson (D-Neb.) and Mary Landrieu (D-La.) notoriously did on the healthcare reform bill. Individual senators also use the threat to filibuster nominees and bills as a way to gain concessions on unrelated issues. And the minority’s ability to stop any and every bill robs elections of their meaning.

Common Cause contends that the current use of the filibuster violates the Constitution in seven ways, but the heart of the group’s case is a conflict between the filibuster and the Framers’ intent that most bills require no more than a simple majority to pass. It’s a persuasive argument, despite the fact that the Constitution doesn’t actually specify how many votes it takes to pass a bill. Instead, it identifies a handful of specific measures that require more than a majority, such as a veto override or a presidential impeachment. The unmistakable implication is that the Framers wanted no other type of legislation to require a supermajority vote.

Defenders of the filibuster note that the Constitution gives each chamber the power to determine how it conducts business. By this line of reasoning, the filibuster is merely an intermediate procedural step in the legislative process, not a change in the number of votes required for passage. That may well have been true for most of this country’s history, when filibusters were rare even when the Senate was sharply divided. It’s not true today. The near-constant use of filibusters has turned a procedural rule into a de facto threshold for passing a bill, and the Senate’s rulemaking power simply doesn’t extend that far.

For Common Cause to succeed, however, it will have to find a set of plaintiffs qualified to sue — a significant hurdle that has blocked at least three previous efforts to have the filibuster declared unconstitutional. The organization will also have to persuade the courts that the dispute over the filibuster isn’t the sort of political question that is more appropriately left to lawmakers rather than judges. That obstacle may be insurmountable. Nothing illustrates the political nature of the situation more clearly than the way members of both parties decry the filibuster when they’re in power but defend it when they’re in the minority.

The Senate could reduce the requirement for ending debate to 51 votes from 60 — and it could do so by a simple majority vote, except that, ironically, the effort would likely draw a filibuster. And under a special Senate rule, any such filibuster would require a two-thirds vote to defeat — an impossible margin. An intriguing option advanced by Akhil Amar, a Yale law professor, would be for Vice President Joe Biden to rule while presiding over the Senate that the filibuster was unconstitutional. Supporters of the filibuster could appeal the ruling, but opponents could sustain it with a simple majority vote. It’s a variation on the “nuclear option” first outlined by Vice President Richard Nixon — a Republican — in 1957, when he issued an advisory opinion holding that previous Senate rules did not bind the current Senate. The phrase “nuclear option” is appropriate, given how much political fallout such a move would take. But restoring majority rule in the Senate is worth the price.