In finding the the WikiLeaks whistleblower Bradley Manning guilty of espionage but not of aiding the enemy, a US military court delivered a verdict which showed a welcome sense of perspective after one of the most convulsive episodes in recent American judicial history.

Nobody suggested that this young, disillusioned soldier had deliberately sent military secrets to Osama bin Laden and al-Qa'ida, but in a highly emotive summing up, the prosecutor, Major Ashden Fein, claimed that “he was a determined soldier with the ability, knowledge and desire to harm the US. He was not a whistleblower, he was a traitor… he had general evil intent. The US has proved beyond a reasonable doubt that his voluntary actions to disclose more than 700,000 documents would lead to them being in the hands of the enemy.”

Manning was responsible for the largest leaking of classified information in US history, and what he did sent shockwaves through America's military and political establishments. Their response to his actions was part of the mindset that materialised after the 9/11 attacks and was most grotesquely manifested in the policies of extraordinary rendition and waterboarding, and the creation of Guantanamo Bay.

Judge Colonel Denise Lind has struck a very different note, and the policies of the Bush presidency which were responsible have been reversed. Nonetheless the malign consequences linger on, including the compulsion in the United States to terrify into silence all those who, like Manning, discovered that the exercise of American power on the ground in Iraq and Afghanistan was drastically different from the way it was advertised back home.

American claims of fostering a culture of free information have often been overblown, and its media have failed to take full advantage of those freedoms they did possess. But the collision of President Bush's “war on terror” with the explosion of information released by the internet - which WikiLeaks came to symbolise - created a national mood of paranoia reminiscent of Stalinism. The winding down of US engagement in Iraq and Afghanistan, and President Obama's refusal so far to countenance any large-scale involvement in Syria or Iran, have served to cool that feverish atmosphere.

Both Bradley Manning and the WikiLeaks founder Julian Assange were guilty of recklessly flooding the media with secret information with little apparent concern for what happened subsequently to the people who had been named. But they also enabled us to learn about atrocities committed by the US military which would otherwise have been covered up indefinitely.

We know why governments and military establishments want to keep their dirty secrets to themselves. We also know why they must not be allowed to. Freedom of information is one of the cornerstones of democracy, and as John le Carre reminded us this week, whistleblowers like Bradley Manning are vital to the functioning of societies that aspire to be free - however obnoxious that notion may be to their rulers.