Bradley Manning is a US soldier who was arrested in May 2010 in Iraq on suspicion of having passed classified military material to the whistleblowing website WikiLeaks. Assigned to an army unit based near Baghdad, Manning had access to databases used by the military to transmit classified information. He was charged with 22 offences by the US government, including those of communicating national defence information to an unauthorised source and aiding the enemy. A military judge on July 30 2013 acquitted Manning of the most serious charge against him, aiding the enemy, but convicted him of most of the other charges including espionage, theft and computer fraud.
Manning conviction shows legal net is closing on whistle-blowers
Bradley Manning's spying conviction and the likelihood of a long jail term send warning to Snowden and any would-be whistle-blowers
Associated Press in Washington
The successful prosecution of Bradley Manning gives a boost to the Obama administration's aggressive pursuit of people it believes have leaked national security secrets to the media - including Edward Snowden - say US legal scholars.
Army private Manning was acquitted on Tuesday of the most serious charge he faced, aiding the enemy, but was found guilty by a military judge of enough charges to perhaps send him to prison for the rest of his life.
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Experts said they expect the government's case against National Security Agency whistle-blower Snowden to be similar to the Manning prosecution, although it would take place in a federal trial court.
"I don't think Edward Snowden is doing a jig in his airport lounge in Russia," said Elizabeth Goiten, of New York University's Brennan Centre for Justice.
Prosecutors were able to convince Army Colonel Denise Lind that the reams of documents Manning gave to WikiLeaks constituted violations of the Espionage Act.
This was despite arguments from Manning's lawyers that he chose to hand over information that he believed would not harm the United States.
Goiten said Lind determined that Manning's intent was irrelevant, although his motives will come into play when the judge considers his sentence.
"He could be convicted even if he had the purest of motives," Goiten said. "What that says is that the Espionage Act will not distinguish between traitors and whistle-blowers."
Before Lind announced her verdict, advocates of press freedoms worried that a conviction for aiding the enemy would have a chilling effect on leakers who wanted to expose government wrongdoing because the charge carries a possible death penalty.
Manning's prosecutors said they were seeking life in prison for Manning, not death. But in the end, Manning's convictions under the Espionage Act and the prospect of many years behind bars could have the same effect.
Charles "Cully" Stimson, of the Heritage Foundation in Washington, said the verdict appropriately reinforced the potential cost to those who want to expose government secrets.
"I think what this sends out loud and clear to anyone like Snowden - or anyone contemplating being the next Snowden - is that if you have given over documents, unauthorised, to anyone, you're looking at serious time in jail," he said.
The Obama administration has pursued unauthorised disclosures of secret information much more aggressively than any of its predecessors. It has pressed charges under the Espionage Act in seven criminal cases.
In addition, a federal appeal court ruled on July 19 that The New York Times reporter James Risen cannot shield his source when he testifies at the trial of former CIA officer Jeffrey Sterling, who is charged with leaking information about a secret CIA operation.
The court ruling, combined with Manning's conviction, will make people think twice before talking to reporters, law professor Mary-Rose Papandrea said.
"It sends a really strong message to would-be leakers that they are facing the potential of prosecution," Papandrea said.
Snowden has been holed up at Moscow's Sheremetyevo airport since he left Hong Kong on June 23. But Attorney General Eric Holder said the US had no plans to seek the death penalty against him.
It is unknown at this point whether the administration will get Snowden to return to the US, either voluntarily or through extradition. But if that happens, "at the end of the day, the charges are going to look very similar" to those against Manning, law professor Stephen Vladeck said.
One difference may be greater transparency if Snowden is put on trial in civilian court.
Manning also opted to be tried by a judge instead of a jury.
Except in death penalty cases, military juries do not have to be unanimous. Jurors in civilian criminal trials must all agree in order to reach a verdict.
Stimson also said Snowden may benefit from "a little more sympathy for a civilian disgorging himself of information he believes the public needs to know, than a military person".