Manning was acquitted Tuesday of the most serious charge he faced, aiding the enemy, but he was found guilty by a military judge of enough charges to send him to prison for many years, and perhaps the rest of his life.
Legal scholars said they expect the government's case against National Security Agency leaker Edward Snowden to be similar to the Manning prosecution, although it would take place in a federal trial court, not a military court-martial.
"I don't think Edward Snowden is doing a jig in his airport lounge in Russia," said Elizabeth Goiten, co-director of the liberty and national security program at New York University's Brennan Center for Justice.
Prosecutors were able to convince Army Col. Denise Lind that the reams of documents Manning gave to WikiLeaks constituted violations of the Espionage Act, despite the arguments of 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 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, Manning supporters and advocates of press freedoms worried that a conviction for aiding the enemy would have a chilling effect on leakers who want to expose government wrongdoing because the charge carries the potential for the death penalty. Manning's prosecutors said they were seeking life in prison for the Army private, not death.
But in the end, Manning's convictions under the Espionage Act and the prospect of many years behind bars could have much the same effect.
Charles "Cully" Stimson, manager of the national security law program at 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 loud and clear to anyone like Snowden or anyone contemplating being the next Snowden is, if you have given over documents, unauthorized, to anyone, you're looking at serious time in jail," said Stimson, a former Bush administration defense official who still serves as a military judge.
The Obama administration has pursued unauthorized 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 appeals court ruled on July 19 that 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, Boston College 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.
Like Manning, Snowden has acknowledged leaking classified information. The former NSA systems analyst provided information showing that the agency has gathered millions of telephone and Internet records to ferret out terror plots.
The Justice Department is not discussing how it would prosecute Snowden, who is holed up at a Moscow airport, although Attorney General Eric Holder has said the U.S. 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 U.S., 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, American University law professor Stephen Vladeck said.
One difference may be greater transparency if Snowden is put on trial in civilian court, where Vladeck said a judge would be less likely to close large portions to the public.
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 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."
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