A year ago, I went to a London pub to speak at a meeting for the apparently doomed cause of libel reform. Simon Singh had written an article which was true and important about the dangers of the quack therapy of chiropractic healing. Then, like so many authors and publishers before him, he learned English law persecuted rather than protected honest argument and that he was in trouble.

The British Chiropractic Association was suing him for saying that there was "not a jot of evidence" that its members could help sick children by manipulating babies' spines in accordance with the teachings of a more-than-usually nutty American faith healer.

Well-run societies do not defend men who make money from worried parents and, more seriously, fob off their children with bogus "cures". In his wisdom, however, Mr Justice Eady decided that the law would intervene to silence a debate on public health and ruled that it would not be enough for Singh to show that there was no reliable evidence that alleged treatments worked, which Singh would have difficulty in doing because there wasn't. Because he had written that the chiropractic association "happily promotes bogus treatments", the judge said he had to jump the insuperable barrier of proving that the therapists were lying rather than merely deluded and face costs of £500,000 or more if he failed.

I expected a glum affair and did not expect my contribution to raise morale. I described how the judiciary had allowed Robert Maxwell, Roman Polanski, Khalid bin Mahfouz and many another actual or suspected criminals to use a biased and prohibitively expensive law to silence their critics. Far from being depressed, the audience turned into a heaving mass of furious geeks, who roared their anger and vowed that they would not rest until they had brought down the rotten system The "skeptic movement" (always spelt with "k" by the way, to emphasise their distinctiveness) had come to Singh's aid. He was now in the protective custody of men and women, who, with straight faces, introduced themselves by the titles of their blogs: "Hi, I'm Gimpy."

"Jack of Kent, pleased to meet you, love your writing. This is Holford Watch, Zeno, Jago, and I thought I saw the Quackometer getting a round in at the bar."

Unnerved by their determination, I said to Ben Goldacre, demolisher of pseudo-science in all its fraudulent forms: "The nerds are on the march. I wouldn't like to be the one standing in their way." An uncharacteristically mystical look passed over the great debunker's face. "Yes," he said. "Strike us down, we shall become more powerful than you could possibly imagine."

It was only later that I realised this is what Obi-Wan Kenobi says to Darth Vader in Star Wars and that the Skeptics movement's highest cultural reference point was a 1970s' B-movie. I shouldn't have mocked. More to the point, neither should the English establishment.

One year on, the Singh case has led to the Court of Appeal issuing the most ringing defence of freedom of speech in living memory. Senior judges, who previously had not appeared to have known the difference between John Milton and Milton Keynes, quoted from "Areopagitica" as they severely limited the ability of libel lawyers to censor scientific debate. The BCA realised that it could not hope to win and dropped its case. The Lib Dems, Labour and the Tories responded to an outcry which was turning into a popular movement and included commitments to libel reform in their manifestos. We're not there yet, but a hopeless cause has become a national issue.

Credit for moments like this should always be widely spread. Singh deserves the most. Thousands who have confronted the possibility of a libel action have self-censored or backed down.

Singh decided to stay firm and stand by the tradition of British liberty, which has not on the whole been made in revolutions and with bills of rights but by cussed men and women who, when confronted with an injustice, refuse to bow their heads before it. His lawyer, Robert Dougans, produced a brilliant argument which persuaded the senior judiciary to look to the free spirit of American law rather than the more authoritarian traditions of Europe. Sense About Science, Index on Censorship and Pen organised a textbook reform campaign which lobbied Parliament and mobilised concerned academics. And after watching Dara O Briain, Robin Ince and Dave Gorman give their time to the cause selflessly and without complaint, I swore to myself that I would never again bait "luvvies" who got involved in politics.

Yet the energy and novelty behind the campaign came from skeptics connected by the net. Within a day of the chiropractors giving the court their argument that they could help sick children, scientists online had taken it apart brick by brick until nothing was left but a heap of rubble.

Meanwhile, their allies tracked down the web pages of every chiropractor in Britain who was claiming they could treat asthmatic children and reported him or her to their local trading standards officer. Every court hearing and public meeting was packed by people with an unwavering belief in the importance of the scientific method and evidence-based policy. Skeptics are less interested in what people think but in how they think.

There is an overlap with the more assertive atheism which followed 9/11. Like atheists, skeptics treat as patronising and contemptible the cynical modern belief that you should not examine religion or alternative medicines because the simple-minded and uninformed find comfort in them. But you do not have to be an atheist to be a skeptic, merely commit to the free examination of evidence. This modest ambition is surprisingly potent.

Politicians who supported libel reform had a smart and committed network behind them. I suspect that politicians who still want to defend our irrational drugs laws or alternative treatments on the NHS will find that they will face unrelenting scrutiny from equally smart and committed opponents. My hope after Singh's victory is that none but the foolhardy will want a repeat of the drubbing the chiropractors received.