The longest-running comedy in America is not “The Simpsons,” “Cheers,” or “M*A*S*H*”—but Congress. Take the Senate (please!), where Democrats are trying to curb the use of the filibuster.

Senate Majority Leader Harry Reid has promised to do just that when the new Congress is sworn in. As he put it this summer, “we have to change the rules. We can’t go on like this anymore.... We can [change the rules] with a simple majority at the beginning of the next Congress.”

This stands in marked contrast to what Reid was saying a few years ago—when Democrats were in the minority and Republicans were the ones trying to change the Senate rules.

“For people to suggest that you can break the rules to change the rules is un-American” Reid fumed in 2005. “To change a rule in the Senate rules to break a filibuster still requires 67 votes. You can’t do it with 60. You certainly cannot do it with 51.... It is illegal. It is wrong, you can’t do it.... It is very un-American.”

Yet that, hilariously, is precisely what he plans to do now.

Equally hilarious: Republicans now are saying exactly the same sort of things Democrats were saying in 2005. In late November Senate Minority Leader Mitch McConnell accused Reid of engaging in a “systematic effort to marginalize the minority.” Sen. John Cornyn now decries what he sees as “an abuse of power.” Sen. Tom Coburn warns that “the backlash will be severe.”

There was a time, long ago, when the filibuster arguably served the cause of good government by checking majority power. This is arguable because while the tyranny of the majority is a real danger, majorities are not always wrong.

In any event, those days are shrouded in the mists of history. For at least the past two decades, Democrats and Republicans have used the filibuster far more for petty partisan purposes than to ensure robust debate on the great questions of the day.

A few years ago the Republican majority in the Senate got fed up with Democratic filibustering. McConnell accused Democrats who were blocking Republican judicial nominees of endangering the Constitution itself. Cornyn denounced “this unconstitutional use of the filibuster to deny the president his judicial nominations.” Sen. Rick Santorum compared Democrats to Hitler.

So in 2005, Republicans proposed the “nuclear option”—changing the Senate rules with a simple majority vote. They even produced a report justifying what they termed the “constitutional option,” on the grounds that “the Senate has always had, and repeatedly has exercised, the constitutional power to change the Senate’s procedures through a majority vote.”

Democrats and liberals went (pardon the term) ballistic.

“The filibuster,” declared Harry Reid, is “the last check we have against the abuse of power in Washington.”

“A careful review of the Senate’s precedents,” said the liberal People for the American Way, “reveals that the Senate has never acted by simple majority vote to force an end to a filibuster or a change to the Senate’s rules of debate.” Today, you can sign a PFAW petition to “End the Unprecedented Partisan Obstruction: Stop Filibuster Abuse Now.”

In 2005, The New York Times somberly warned that the GOP’s “deeply misguided” attempt to change the Senate rules “poses a real danger of permanently damaging the system of checks and balances at the heart of American democracy.” This past November, the newspaper touted “A New Chance for the Senate”: Democrats, it said, “can vastly improve the efficiency of Congress and reduce filibuster abuse with a simple-majority vote. This time they need to seize the moment.”

Seven years ago, Washington Post columnist E.J. Dionne denounced GOP efforts to circumvent the filibuster as “regime change disguised as a narrow rules fight.” Now, he terms GOP use of the filibuster “extra-constitutional ... obstructionism.”

Seven years ago, the Heritage Foundation called for “ending the filibuster of qualified judges.” Now, Heritage deems the filibuster “the soul of the Senate” and attempts to reform it a “partisan power grab.”

Some of those singing a different tune now try to justify their switch by suggesting that the situation today is different from the situation a few years ago: Today’s filibusters are somehow worse (or better) than yesteryear’s. A few may actually convince themselves, momentarily, that we have always been at war with Eastasia. But at bottom they’re really just blowing smoke. When control of the Senate switches back, so will they.

That’s what makes January the perfect time to debate filibuster reform. The month was named after Janus—the Roman god who had two faces.