Army private faces sentence of life in military custody with no chance of parole if convicted on 'aiding the enemy' charge

Bradley Manning, the self-confessed source of the massive WikiLeaks trove of US state secrets, will learn his fate on Tuesday when a military judge announces her verdict in the most high-profile prosecution of an official leaker in at least a generation.

The army private faces a possible sentence of life in military custody with no chance of parole should Colonel Denise Lind find him guilty of the most serious charge – that he knowingly "aided the enemy" by transmitting intelligence to WikiLeaks.

In the course of the eight-week trial, which ended on Friday, the US government sought to create a new precedent by arguing that Manning knew he was helping al-Qaida when he released more than 700,000 documents to the anti-secrecy website.

The verdict will be issued at 1pm ET by Lind sitting alone in the courtroom at Fort Meade, Maryland, in the absence of a jury – an arrangement made at Manning's own request. The soldier's decision to put his faith in a military judge, rather than in a panel of his peers – the military equivalent of a jury – was a big legal gamble whose merits will become clear when the verdict comes in.

In another huge legal roll of the dice, Manning decided to plead guilty to a lesser version of 10 of the 21 counts of which he is accused, carrying a possible maximum sentence of 20 years in military jail. He did so with nothing in return in the form of a plea bargain, a highly unusual step in criminal proceedings.

The outcome of the trial has huge potential ramifications, not just for Manning personally but for the wider health of investigative journalism in the United States. Leading media experts have warned that a guilty verdict on the most serious charges could send a devastating chill across news outlets by frightening away potential official leakers.

The impact of the aggressive prosecution of Manning can already be seen in the actions of Edward Snowden, the NSA leaker, who told the Guardian that he was partly motivated to flee the country having watched the harsh treatment that the US soldier received at the hands of the military.

The verdict will also put a potentially enduring stamp on how the US authorities regard individuals disclosing official secrets.

During the course of the trial, two starkly contrasting interpretations of Manning emerged.

On the one hand, the prosecution portrayed him as a traitor who had no allegiance to the American flag, driven by a desire for fame and notoriety. On the other, the defence depicted him as a naive but well-intentioned young man who was motivated by deep Humanist beliefs and who wanted to prompt a debate within US society about the costs of war.