Last night Senator Rand Paul from Kentucky led a 13-hour filibuster of the nomination of John Brennan to head the CIA. Based on a couple questions from friends I’d like to explain how a filibuster works and why they are so rare.


At almost any point in time the Senate is technically either debating or voting on a yes or no question. Typical questions the Senate considers look like this:

  • Should amendment A by Senator B to bill C be adopted?
  • Should the Senate pass bill C?
  • Should the Senate consent to the nomination of person D to job E?
  • [Now that it has finished F,] Should the Senate next proceed to working on G?

Most questions the Senate considers are debatable. This means that any of 100 Senators, or all of them, can speak about the question for as long as he or she wants.

A few types of questions are non-debatable. As soon as the question is asked, the Senate immediately proceeds to vote on the question. Nominations are debatable questions.

There’s a middle ground as well, used mostly for two types of fiscal policy legislation. The Senate has a fixed amount of total time to debate a budget resolution or a budget reconciliation bill.

How a filibuster works

A filibuster is probably better labeled extended debate. To filibuster a question, there isn’t some formal procedural move you make. You simply get recognized by the presiding officer to speak on a debatable question, start speaking, and don’t stop. You talk, and talk, and talk, and talk. At some point people say, “Hey, he’s filibustering,” but there’s no bright line between a filibuster and a really long floor speech. As a procedural matter they are identical.

There are a few interesting technical limitations once you have been recognized to speak. These apply at any time you are recognized to speak on the Senate floor but are particularly important during extended debate.

  • You can’t sit down. If you do, you have yielded the floor and the Chair will recognize someone else to speak.
  • You can’t eat on the Senate floor. You can drink water or milk, nothing else.
  • You can’t leave the Senate floor, even for a bathroom break. If you do you have yielded the floor and the Chair will recognize someone else to speak.
  • You don’t have to discuss the pending question. You can talk about anything you want. You can read a book aloud if you like.
  • You can only speak once on any particular question.

These limits create some practical limitations on how long a single Senator can filibuster a particular question. At some point you’ll get tired of talking continuously and need a momentary break. If you’re talking a lot you’ll drink something, and that will at some later point provoke a need for a bathroom break.

You can solve the first problem by yielding for a question. Here’s an example which I saw Senators Paul and Cruz implement last night. Note that the “question” itself is substantively irrelevant. The procedural point is to allow someone else to speak for a while while technically maintaining control of the floor.

Sen. A: <discusses the question of the Brennan nomination for a couple of hours>

Sen. B: <interrupting> Will the Senator yield for a question?

Sen. A:  I yield for a question from my good friend Senator B.

Sen. B:  Is the Senator aware that … <talks for an hour or three while Senator A stretches, walks around a bit, and enjoys not speaking, all the while remaining standing and on the Senate floor>

Sen. A:  No, Senator B, I wasn’t aware of that, but thank you for asking. <continues discussing the question for a few more hours>

Through this “friendly yielding for a question” a single Senator can continue his filibuster for quite a long time while his or her allies are doing the speaking for much of that time. Other Senators C, D, and E could additionally play the role that Sen. B plays above.

In addition, at some point Senator A may tire and yield the floor, probably for a bathroom break if nothing else. At that point any other Senator could seek recognition and begin his own period of extended debate. Therefore, if you have a group of Senators teaming up, you can keep a filibuster going for a quite a long while.

Cloture: stopping a filibuster

There are two ways to limit debate: in advance by unanimous consent and while it’s occurring by invoking cloture. If neither of these occurs a question can be debated for as long as Senators are willing to speak.

A unanimous consent (UC) agreement to limit debate looks like this:

Majority Leader: Mr. President [of the Senate], I ask for unanimous consent that debate on this amendment be limited to two hours, with one hour under control of the committee chairman Senator X and one hour under the control of the committee’s ranking member Senator Y.

Presiding Officer of the Senate: Is there objection?  <pauses to allow any Senator to object> Hearing no objection, it is so ordered.

Any single Senator can block a UC request to limit debate simply by standing when the UC request is made and saying the two most powerful words in Senate procedure: “I object.” In doing so she ensures that she and her colleagues can engage in extended debate until and unless the Senate invokes cloture.

Let’s say a group of Senators have been debating a question for a couple of days straight and show no signs of letting up. The Senate majority leader says to himself, “That’s it, we need to shut down this filibuster and bring this debate to a close.” He then finds 15 other Senators to join him in filing with the Senate clerk a cloture motion to limit further debate on this question.

If they do this today, the cloture vote will “pop up” automatically the day after tomorrow, one hour after the Senate begins business for the day. The extended debate will be automatically interrupted for the cloture vote. If at least three-fifths (60) Senators vote to “invoke cloture,” then further debate on that question is automatically limited to 30 additional hours, then followed by a vote on the question. If cloture is invoked, those involved in the filibuster usually fold after a few additional hours, not burning all of their allowed 30 hours of post-cloture time since they know that they can no longer infinitely delay a vote on the question.

The power to invoke cloture and shut down extended debate is a big deal, but the cloture process is cumbersome for two reasons. First, it’s still quite slow. Even if the cloture vote is successful, the Senate will burn 2-3 additional days of floor time on the filibustered question. Second, the majority leader must find an affirmative 60 aye votes (rather than requiring the minority to produce 41 or more votes against cloture), so the majority leader has to make sure everyone he needs to vote aye will actually show up and vote. This last factor helps explain why filibusters are so rare.

Why filibuster when you can just threaten to filibuster?

Let’s say you’re a Senator who really, really, really hates a particular amendment to a bill the Senate is now considering. You approach the bill manager, a committee chairman, and threaten to filibuster the amendment.

You: Mr. Chairman, I hate this amendment and intend to debate it indefinitely. I have several colleagues who have promised they will assist me in this task. I know you support the amendment, but I’m guessing it’s not as important to you as the underlying bill that you wrote. I support your bill, but if this amendment is adopted I’ll have to filibuster the underlying bill as well.

Chairman: I appreciate that, but the amendment sponsor is a close ally of mine. I’m sorry, I can’t help you. And I’m fairly confident that I can get 60 votes to invoke cloture and shut down your filibuster.

You: Yes, but that will cost you two, maybe three days. And I’ll slow you down at every stage of the process. You’re under pressure from the majority leader to finish this bill soon, and you have plenty of other Senators who want to offer other amendments. If you force me to, my colleagues and I will slow the process down enough so that the leader will tell you he’s pulling your bill to move onto other legislation, because it will be clear you’re not going to get the bill passed in the next few days given my filibuster.

Chairman: OK, I believe that you’re serious in your threat. I’ll tell the amendment sponsor I want him to drop his amendment or else I’ll be forced to oppose it to protect my bill from your threatened filibuster.

Note that you never had to filibuster the amendment. You just had to threaten to filibuster it. Maybe the Chairman asked for UC to limit debate, knowing that you would object, so he could demonstrate to his ally the amendment sponsor that you were serious in your threat. By simply threatening to filibuster the amendment and slow down the bill, you achieved the same objective as if you had actually filibustered it.

The simplest reason why there are so few filibusters is that it’s almost never necessary to filibuster a question to block something you hate. You simply have to threaten to filibuster and maybe object to a UC or two. Then the majority leader and/or chairman managing the bill or nomination usually fold to your demand or at least negotiate a compromise with you.

Why doesn’t the majority force a Senator to carry out his filibuster threat?

Your exchange might instead have ended like this.

Chairman: Sure, you can slow me down, but filibustering is hard work. You can slow things down, but to do so you and your friends will need to stand on the Senate floor for the next two days, day and night, talking the whole time. You have other things to do and some of your colleagues are quite old and need their sleep. And frankly I’m sick of you threatening every bill I bring to the floor, so this time I’m calling your bluff. Maybe you can slow down my bill and maybe the majority leader will pull it from consideration because it’s taking too long. But I’ll bet you and your colleagues tire and end your extended debate tonight sometime around 1 AM. I will then be able to continue moving forward with amendments, and we’ll pass this amendment that you hate and I support. I’m filing my cloture motion now. If you want to filibuster, go right ahead. I’ll wait.

In this scenario you and your colleagues could still probably kill the bill by slowing it down for at least a few days, hoping the majority leader will move on to other items. But doing so would cost you a lot. The temporary hassle of staying overnight isn’t the significant cost, it’s the burden you’d be imposing on your allies who join to help you. All of you will be severely limited in the work you can do on other topics during that time. If every once in a while the majority leader and/or bill managers forced those threatening filibusters to actually stay all day and all night, then threats to filibuster would involve some cost that the bluff would be called. Filibusters would be more frequent and filibuster threats less so. The most fiercely debated questions would be subject to all-night filibusters, and the threats to slow down legislation on smaller questions would be relatively infrequent.

So why doesn’t this ever happen? It turns out there is a procedural reason that imposes much greater costs on the majority when the bluff is called.

Why doesn’t the majority leader ever force those threatening a bill to engage in a real filibuster?

Technically a majority of Senators (51) must be present on the Senate floor to do any business. This is called a quorum.

Since it would be super inconvenient for 51 Senators to have to sit on the floor all day when the Senate is in session, the Senate almost always operates with a presumptive quorum. The Senate simply pretends that a quorum exists and they don’t count noses on the floor. Everyone knows that there are typically only a handful of Senators on the floor at any given moment, but they “presume a quorum is present” so they can keep doing business without inconveniencing all of their colleagues and forcing them to be present on the Senate floor.

The trick is that at any point in time, any Senator can challenge this presumption by “suggesting the absence of a quorum” to the Chair. After a while the Chair will have to initiate a mandatory quorum call, in which the Senate Sergeant of Arms has to find Senators and bring them to the Senate floor. If this fails and at least 51 Senators don’t show up, then the Senate automatically adjourns for the day and convenes the next morning.

This is the key procedural weakness that makes the majority leader hesitant to force Senators to carry out their filibuster threats. Suppose last night Senator Paul and a few of his colleagues had kept their filibuster going until 2 AM. At that point Senate Majority Leader Reid would still be around, as would be Senator Paul. Senator Paul could then suggest the absence of a quorum. There clearly aren’t 51 Senators present, so a mandatory quorum call would soon begin. Most other Republican Senators, who are sympathetic to Sen. Paul’s filibuster but aren’t participating, would be sleeping soundly in their beds and would ignore the mandatory quorum call when the phone rings.

But Leader Reid wants to force Sen. Paul to continue filibustering, so Leader Reid needs to keep the Senate operating in the face of the mandatory quorum call. Leader Reid must therefore get 51 Senators to the Senate floor at 2 AM, and he’s probably limited to working with a universe of 55 Democrats sympathetic to his situation.

If Leader Reid can’t produce 51 Democratic Senators on the floor at 2:15 AM, the Senate adjourns for the night. Senator Paul can get several hours of sleep, freshen up, and begin again.

If Leader Reid succeeds, Senator Paul can wait until the very grumpy Democrats leave, then again suggest the absence of a quorum, maybe at 3 AM. And then again at 3:30 AM, and at 4 AM. He can do the same the next night, since cloture doesn’t “ripen” until after two nights.

Senator Paul only has to inconvenience himself by staying all night, maybe joined by a colleague or two who is equally fervent and committed to the filibuster.

Leader Reid must get 51 Democratic Senators to the floor at any time of night (or day) that Senator Paul feels like initiating a quorum call, and as many times as Senator Paul would like. Calling Senator Paul’s bluff of a threatened filibuster means Leader Reid must inconvenience his entire caucus, probably forcing them to sleep on cots in the Capitol building for two nights in a row.

Senators are powerful, independent types. Their average age is around 60. If you’re the majority leader and you’re trying to break a filibuster on a major piece of legislation that is a top national or your party’s top priority, then you can probably persuade 50 of them to foul up their schedules and to join you in sleeping in the Capitol for a couple of nights. But you can’t do this too often, and if you’re asking them to do so on a relatively minor amendment or bill, some of them are going to say no.

The majority leader and his bill managers usually yield to credible filibuster threats because they assess that they cannot rally enough of their colleagues to bear the personal and schedule costs of breaking the filibuster, or because the long-run cost of asking them to do so on this particular issue is significantly higher than the cost of yielding to the demand or negotiating a compromise.

Congratulations to Senator Paul and his colleagues for reviving the old-school filibuster.