The United States government limits how much companies can disclose about their cooperation with surveillance by the National Security Agency and other federal agencies. Government officials have insisted that Internet companies such as Google and Microsoft report the number of surveillance requests only in broad numeric ranges. In a Thursday blog post, Twitter wrote that it was unsatisfied with this arrangement, and was "considering legal options we may have to seek to defend our First Amendment rights." The company argues that it has a right to disclose specific details about the extent of its participation in U.S. surveillance programs.

Would such a legal challenge succeed? To find out, I asked Eugene Volokh, a prominent First Amendment scholar at the University of California-Los Angeles. His blog, the Volokh Conspiracy, is hosted by the Washington Post. We spoke by phone on Friday. The transcript has been edited for length and clarity.

Timothy B. Lee: How likely is it that Twitter would succeed if it challenged the government's rules limiting how much information Twitter can disclose about the company's cooperation with government surveillance?

Eugene Volokh: It's hard to know what the chances of success would be, but the position of Twitter is perfectly sensible on this. You have information about the government and what the government is doing. You might think the government is doing something bad, but the law says you can't talk about it. Maybe you can talk about it in a very general sense. But you can't say "look here's the subpoena the government issued to us, we complied with it, but we thought it was unjustified, we think we should be allowed to tell people about it, we think the law should be changed to prohibit this." The law doesn't allow Twitter to do that.

I can also understand the government's position. If you reveal [information], it will tip off suspected criminals or terrorists. National security letters with gag orders attached have become more prominent, but these kinds of statutes have been around for a while. I can see what the government's argument would be. I will be interested to see what the courts can say about it. There have been several decisions, some moderately pro-speaker, some less so. We ultimately don't know what the courts will say.

How much does it matter if service providers can provide detailed information, as opposed to just general facts?

In any debate about public policy, if one side is barred from giving details, it's going to be handicapped. The best arguments, the most persuasive arguments, are arguments that link a broad point to specific, concrete examples. [You want to be able to say] "look here's what's happening, here's a subpoena we got, here's why the government's rationale is unsound." It's very difficult to do that if you're not allowed to talk about the details. Maybe the government has a good argument that this kind of speech ought to be restricted. But it seriously affects the ability of the public to critique and evaluate these subpoenas.

What are the most important court decisions in this area of law?

The Supreme Court hasn't opined on the subject. The lower courts are still grappling with it, but the analogy that the government is pointing to is grand juries. If you're called in front of a grand jury to testify about something, you're not allowed to reveal information you learned as a result of a grand jury proceeding. This is a centuries-old procedure. Therefore, [the government argues], it should be constitutionally permissible. At the same time, there is a lot of precedent that the government can't stop people from revealing truthful information.

Isn't grand jury secrecy a little different? That seems like a case where it's mostly the government giving the jurors information, rather than vice versa.

If you're called to testify, you learn a lot of things from the questions you're being asked. You probably learn this person is being investigated for this charge. Before that it may have been a secret. The details of the allegations might be secret. But by going in front of the jury you might learn what it is, who's being investigated and what the investigation is about. That's the analogy that the government offers.