Last weekend, for nine hours, British police questioned David Miranda, the twenty-eight-year-old partner of Glenn Greenwald, justifying the stop at Heathrow Airport under a U.K. statute that permits such questioning without charges in cases of terrorism. Miranda was apparently carrying some of the documents that Edward Snowden had stolen from the U.S. government. Whether or not Miranda was a journalist, he was certainly acting as an agent of journalists (his airfare was paid for by the British newspaper the Guardian), a fact the British government knew. In response to extensive criticism, the British Home Office defended itself, saying, in a statement, “If the police believe that an individual is in possession of highly sensitive stolen information that would help terrorism, then they should act and the law provides them with a framework to do that.”

In the wake of Miranda’s detention, Alan Rusbridger, the editor of the Guardian—which has published much of Greenwald’s reporting based on the Snowden leaks—revealed that members of the U.K. government had demanded that the paper destroy its copies of the Snowden documents that were physically present at its offices. If the paper failed to comply, the government would seek a court order preventing publication of the material and requiring it to be returned. (Injunctions preventing publication are surprisingly common in the U.K., where celebrities have been able to stop the media from divulging who they are, or were, sleeping with.) The British government also maintains a set of topics, called “DA-Notices,” about which they ask the media not to report. If journalists do so anyway, “the government department concerned can initiate police and/or legal action, including seeking a court injunction to stop something being published,” according to the government’s DA-Notices Web site. Rather than seeking a reprieve from the U.K. courts, Rusbridger complied, although he pointed out that many other copies of the documents existed outside Britain, and that the destruction of them in London wouldn’t stop the Guardian from reporting its stories. Today, the Guardian announced that it would share some of its Snowden documents with the New York Times.

Could the United States have taken the documents from Miranda as the Brits did? Unlikely. Under the Privacy Protection Act of 1980, the U.S. government generally cannot execute a search warrant on a newsroom or journalist. There are narrow exceptions, however, including if there is “probable cause to believe that the person possessing such materials has committed or is committing a criminal offense to which the materials relate,” which might include the receipt, possession, or communication of “information relating to the national defense, classified information, or restricted data” under the Espionage Act. Conceivably, the possession of the Snowden documents could fall into one of these categories, and the government could seek the documents’ return. But after the recent outrage when the government claimed in an application for a search warrant that the Fox News reporter James Rosen had “aided and abetted” a violation of the Espionage Act—by reporting on material leaked by a government employee—the Department of Justice revised its policies as to when and how it would seek such warrants. Under the revised policy, the government would seek materials under the Privacy Protection Act exception “only when the member of the news media is the focus of a criminal investigation for conduct not connected to ordinary newsgathering activities.” As far as we know, Greenwald, his collaborator Laura Poitras, and even their messengers or agents, such as Miranda, possess the N.S.A. documents only because of their “ordinary newsgathering activities.” Therefore, it would seem that such a seizure of the documents should not happen in the United States. The government could take the documents from Snowden, the leaker, but not from the recipients of the leaks.

And could the U.S. government seek an injunction to block the publication of the documents? It could, conceivably, but such a “prior restraint” bears a very heavy burden, and thus far, at least, the D.O.J. has been loath to go down that path. The question of whether to permit the publication of classified documents that potentially could harm national security was raised in the landmark Pentagon Papers case, and the Supreme Court ruled that the publication could not be stopped. “In the First Amendment the Founding Fathers gave the free press the protection it must have to fulfill its essential role in our democracy,” Justice Black wrote. “The press was to serve the governed, not the governors. The Government’s power to censor the press was abolished so that the press would remain forever free to censure the Government. The press was protected so that it could bare the secrets of government and inform the people. Only a free and unrestrained press can effectively expose deception in government.”

There may be exceedingly narrow situations in which a prior restraint is permissible. “Only governmental allegation and proof that publication must inevitably, directly, and immediately cause the occurrence of an event kindred to imperiling the safety of a transport already at sea can support even the issuance of an interim restraining order,” Justice Stewart wrote at the time. But even the wholesale leaking of information regarding the U.S. security apparatus would not necessarily meet that standard.

The presumption against prior restraint leads to stronger journalism. After all, if you are afraid that the government will be able to keep you from publishing something, there is an incentive to publish quickly—without alerting, or seeking comment from, the government. For good or ill, the major media in the United States has delayed publication of certain information when the government has asked, but if there were a real likelihood of an injunction, those conversations may never have happened.

Similarly, the threat of a restraint on publication provides an incentive to just dump documents all at once rather than thoughtfully and systematically reviewing them—a process, like the information it can uncover, that is very often in the public interest. (Indeed, there is speculation that WikiLeaks just released the Snowden documents in a very large encrypted file, entitled “Insurance.”) The Supreme Court got it right with the Pentagon Papers case. For the very same reasons, the publication of the Snowden materials should not be threatened.

Photograph by Ricardo Moraes/Reuters/Corbis.