THERE seems to have been a misapprehension that the US army whistle-blower, Bradley Manning, got off relatively lightly in court this week because he was exonerated of the charge of aiding and abetting the enemy.

That offence could theoretically have led to the death sentence. But what he was found guilty of were 17 counts under the 1917 Espionage Act, carrying up to 136 years in jail, which is hardly a walk in the park.

This is the first time that the laws on espionage have been successfully used against a citizen who was clearly not spying for a foreign power. Which means that investigative journalism and freedom of speech is now under sentence in the very country that made it a constitutional right. The Wikileaks founder, Julian Assange, still holed up in the Ecuadorian embassy in London, can be in no doubt what will happen if he is extradited to America. Nor can the other fugitive US whistle-blower, Edward Snowden, who exposed the massive surveillance by the US National Security Agency (NSA). Yesterday he revealed how the NSA searches a vast database of emails, browsing histories and the private Facebook messages of millions of individuals.

Private Bradley Manning, a very junior defence analyst in Iraq, leaked relatively low security diplomatic communications which were an embarrassment to the US Government, in that they revealed the private thoughts of US diplomats about foreign contacts. But there has been no evidence that any civilians or military personnel were endangered by his actions. Indeed, since Pte Manning helped expose shocking attacks on civilians by US military aircraft, including one in which a Reuters correspondent was killed, he surely had a strong defence that it was in the public interest to know.

His conviction for spying sends a dark message to every potential whistle-blower that the state is prepared use the full force of the law to crush anyone – other than itself – who leaks digital information. It will certainly curb the enthusiasm of newspaper proprietors and editors for using such material. It will make journalists working in the intelligence field wary of handling leaked material illegally acquired, if for no other reason than to protect the whistle-blowers.

Compare and contrast Pte Manning's treatment with that other security scandal: last month's revelations that the US National Security Agency was routinely keeping and scanning millions of telephone calls and private emails with the apparent connivance of the big internet companies and mobile phone operators. James Clapper, the head of the NSA, seriously misled Congress in denying that such material was being collected. Yet he has not been taken to court. President Obama appeared to endorse this astonishing invasion of privacy on grounds of national secur­ity. No-one need be worried who has done no wrong – the lie perpetrated by every dictatorship in history to justify surveillance of innocent citizens.

This is a digital dystopia that George Orwell could never have imagined. The internet is an invaluable tool for spreading and exchanging information and for facilitating community action. But it is also – potentially – a monstrous machine of surveillance and intrusion, an all-seeing eye that, in the wrong hands, could destroy freedom as we have understood it since the 17th century. These legal judgements are milestones on the way to digital serfdom.

The capacity of the internet to track, in minute detail, our actions and thoughts is something completely new in the armoury of state power. Without realising it, we have created an apparatus that has the potential to know everything about us – our movements, our contacts, our financial affairs, our personal histories and political attitudes. Never before have state agencies had this kind of access to our private lives. The internet has created a window into our souls.

Government may soon be able to know everything about you – what you buy at the supermarket, the books and articles you have read, porn sites you might have visited, dumb or illegal things you might have said on Twitter or other social media sites, ill-judged comments you might have committed to email. Then there is all the official information retained about you – police and credit records, malicious accusations made by work colleagues. It's all out there forever, a digital cloud of searchable information hanging over every citizen.

You might think that all this information, the sheer volume of it, is in some way a protection against surveillance. For, how can any one person digest it all? But that isn't how the state works. It doesn't need to understand the whole picture. It isn't interested in truth, only record.

With search engines, and access to databases, even the dimmest policeman or bureaucrat can now find out if you have ever said anything that might be construed as thought crime. The agencies of the state may soon have the ability, literally at their fingertips, to destroy any opposition politician, civil rights campaigner, trade unionist, lawyer or whistle-blower they don't like.

But why, you ask, would the state want to do that? Aren't they on our side, protecting us against criminals and terrorists? After all, we elect the government and so shouldn't we expect it to watch over us? But if history tells us anything it is that power corrupts and absolute power corrupts absolutely. Governments, however good their intentions, cannot help resorting to underhand methods to control and manipulate public attitudes. Remember Tony Blair and David Kelly, the dodgy dossiers, three months' detention without charge for terrorist suspects.

The permanent agencies of the state, the security services in particular, are anyway largely independent of the elected government of the day and often promote their own institutional interests. In the 1930, J Edgar Hoover, the boss of the FBI, held files on all the politicians of the day and used his privileged information to intimidate and manipulate politicians and rival agencies. Imagine a Hoover on Google.

But hasn't Google promised to "do no evil"? What is worrying is that these young companies have acquired immense power through the management of information while being both highly centralised and often politically naive. Geek billionaires scarcely out of university are innocent of the ways of government. They have been willing to connive with the Chinese dictators in censorship of the internet and have unwittingly assisting the US authorities in one of the greatest act of unlawful surveillance in history – Prism. The technology they have developed to mine databases of personal information, initially in pursuit of profit, could be immensely damaging in the wrong hands.

The agencies of the state will use the power of the law to protect their monopoly of information, and crush any individual who tries to use information technology to expose the dark side of government. This is nothing short of a digital Leviathan. And we should commend the courage of those brave individuals who have dared to stand up to it.