Julian Assange’s lawyers are saying that a US indictment is imminent. But what crime would he actually be guilty of? The Congressional Research Service pointed out earlier this week, in a fascinating document published on Steven Aftergood’s always enlightening Secrecy News, just how difficult it would be to nail him.

Past prosecutions have been almost entirely of individuals who have access to classified information and leak it to foreign agents (not to the press for publication).

And there are no cases of publishers being prosecuted. There have been calls for Assange’s prosecution under the Espionage Act, which covers the leaking of documents relating to the US’s national defence. Yet although some of the diplomatic cables would fit that category, it is not illegal to disclose the information unless you are a government employee.

The US government would have to prove that Assange was disseminating documents with intent to harm the US’s national security — and here, once again, the act of publishing the documents is unlikely to be an offence and would be protected by the First Amendment.

The Supreme Court has been wary in the past of using the Espionage Act to punish whistleblowers “who reveal information that poses more of a danger of embarrassing public officials than of endangering national security”.

Extradition would also be immensely complex, not least because it is not allowed when the offence is political.