The arrival of WikiLeaks is one of the most exciting developments in the enduring struggle of ordinary people for the right to call secret power to account. This is what journalism should do.

For all the lip-service paid to Edmund Burke's idea of a fourth estate, the media remain an extension of the established order. The current wars demonstrate this. Instead of exposing the lies that have led to the carnage, journalists, with honourable exceptions, have amplified and echoed them. Scott McClellan, George W Bush's former press secretary, says his administration relied on the media's "complicit enablers".

WikiLeaks, says its founder Julian Assange, has "created a space that permits a form of journalism which lives up to the name that journalism has always tried to establish for itself". This year, WikiLeaks has released tens of thousands of official documents that describe the casual, almost industrial killing of civilians, assassination squads, and attempts at cover-up.

Anyone watching the leaked cockpit video of an Apache helicopter gunning down cameramen and children in Baghdad will not forget the pilot's reaction: "Nice." Having witnessed the brutalising effects of war, I felt like cheering when this was exposed and I read that it was viewed 4.8 million times in one week. This is the new "space" for a truth-telling we need urgently, as great power promotes its "perpetual war" and strives for what it calls "information dominance".

I have got to know Julian Assange, and what strikes me most about him is the unabashed morality he invests in WikiLeaks. It is unusual to hear the words: "The goal is justice, the method is transparency." He reminds me of one of our compatriots, Wilfred Burchett, the courageous reporter who incurred the wrath of the powerful by exposing the "atomic plague" of the Hiroshima bomb. Like Burchett, Assange has made some serious enemies for blowing such a loud whistle; the Pentagon has already threatened to "terminally marginalise" WikiLeaks. And this is his great risk and his honour.

I asked him what he had learned most from his glimpses of rampant power. "In one way or another I've been reading generals' emails since I was 17," he said (he is 39), "and what I see now is a vast, sprawling estate that is becoming more and more secretive and uncontrolled. "This is not a sophisticated conspiracy; it is a movement of self-interest to produce an end result that is [the wars in] Iraq and Afghanistan, which are used to wash money out of the US tax base and back to [arms] companies like Northrop Grumman and Raytheon." Another release of leaked documents is due soon.

I salute such principled audacity.

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