The thing to remember about the filibuster debate currently roiling the Senate is that it has happened before. And not all that long ago.

It is not easy to prove in a granular, numerical way that GOP obstructionism of nominations in particular is unprecedented, because there are many ways to cut and evaluate the numbers.

In 2005, Republicans were the majority party in the Senate -- they had 55 seats, one more than Democrats hold today. The two parties had been fighting a long and ugly war over President George W. Bush's judicial nominees. After Bush's re-election in 2004, Democrats, with just 45 votes, ran out of ways to stop those nominees short of resorting to a filibuster, which was unheard of even by the rough standards of judicial confirmation fights.

But Democrats ploughed ahead, filibustering not one or two but an entire slate of Bush nominees. The problem for the GOP was that, even though the Democrats' tactics were unprecedented, the Senate's rules allowed them to do it. That made it very hard to stop, since the rules also specified that it takes a big majority -- 67 votes -- to change the rules.

What to do? Republicans threatened to use an arcane parliamentary maneuver that they claimed would allow them to change the Senate's rules with a simple majority -- 51 votes. Democrats were not just opposed; they believed using that method to eliminate the judicial filibuster would be nearly the end of the world. The tactic earned its name: the "nuclear option."

With Armageddon looming, lawmakers did what they often do when faced with an intractable problem: They formed a bipartisan Gang. What became known as the Gang of 14 began negotiating a way out of the deadlock.

After much talk and struggle, the Gang reached a deal: Republicans would withdraw their nuclear threat, while Democrats would promise to resort to the filibuster of judicial nominations only in "extraordinary circumstances." In practical terms, the Gang agreement allowed a few Bush nominations to die -- a sacrifice to satisfy Democrats -- while Democrats allowed confirmation of several nominees they had earlier portrayed as threats to the Republic.

It was a classic compromise, and there was plenty for both sides to be unhappy about. Democrats gained from their obstruction; they had used extraordinary tactics to kill a few deserving nominees. But Republican strong-arming also meant that a number of other deserving nominees were confirmed.

Now both sides are at each others' throats again, this time over Republican use of the filibuster to stop some of President Obama's executive branch nominees. Majority Leader Harry Reid is threatening to use the same maneuver Republicans threatened in 2005.

Reid says GOP obstruction is unprecedented, a claim that is difficult to substantiate. Republicans say they've blocked just a few nominations, while Reid has failed to bring many others up for votes. Even an enthusiastic supporter of filibuster "reform," the liberal Washington Post blogger Greg Sargent, writes that "it is not easy to prove in a granular, numerical way that GOP obstructionism of nominations in particular is unprecedented, because there are many ways to cut and evaluate the numbers."

That alone suggests it's not a good idea to blow up the Senate over a debatable proposition. But at this point, there are no Gang of 14-style talks going on. An explosion is coming.

Given all that, some Democrats argue that things can't get much worse. But they can.

For example, nearly everything the Senate does requires that senators first agree to direct the body's attention to this or that subject. That is usually done through a routine procedure called unanimous consent. But if just one senator wants to stop things, he or she can.

"Most people underestimate the importance of unanimous consent and how it will, if denied, slow down the operations of the Senate, perhaps to a halt," says John Cornyn, the number-two ranking Republican in the Senate. "I can foresee a circumstance where every time there is an effort to do something on the floor, there is going to be an objection, and that will string out for a long time."

If Reid goes ahead with his threat, Republicans will certainly shut down the Senate for a while; a nuclear winter will follow the nuclear option. But that is just a temporary matter. Far more serious is the GOP retaliation that is sure to come at some point in the future.

Someday, there will be a Republican majority, and there will be some issue critical to minority Democrats, or some nominee key to their future, or some GOP initiative they believe it is vital to stop. That's when Republicans will take their revenge. For better or worse, for all its vaunted gentility, the Senate operates on an eye-for-an-eye basis. If Democrats break the filibuster today, someday they will find themselves hoist by their own petard, with no Senate rule to use in their defense.

Byron York, the Washington Examiner's chief political correspondent, can be contacted at His column appears on Tuesday and Friday at