We all know that libel tourism is a major industry in England. Many oligarchs and petro-billionaires have sued or threatened to sue here using our draconian libel laws and the threat of our incredible lawyers costs in order to gag people who criticise them - even where the defendants live in other countries altogether. Major foreign corporations have done the same thing in order to stifle debate in the scientific world.

But this case was home grown. It started with an article in the Guardian. It was a response to the promotion of 'Chiropractic Awareness Week'. The writer, Simon Singh, a physicist turned journalist called into question the claim by the British Chiropractic Society (BCS') - that manipulation of the spine "can help treat children with colic, sleeping and feeding problems, frequent ear infections, asthma and prolonged crying". He said that there was not a jot of evidence to support the claim and continued: "This organisation is the respectable face of the chiropractic profession and yet it happily promotes bogus treatments.".  At this point the sky fell in. The BCS demanded a retraction. Simon Singh refused. The Guardian offered them a right of reply, but this was rejected by the BCS and they instead issued a writ for libel against Simon Singh personally. Mr Justice Eady decided that Simon Singh could not use the usual journalistic defence of fair comment on a matter of public interest because he had alleged 'verifiable facts' rather than stating an opinion. And, to everyone's surprise, he held that the phrase 'it happily promotes bogus treatments' meant that the BCS was being directly accused of dishonesty. To win, Simon Singh would have to prove not only that the treatments were bogus but that the BCS knew them to be bogus.

Now this is not the only instance of English libel proceedings being used in a way which stifles scientific comment worldwide. Peter Wilmshurst is not a rich man. He is an English consultant cardiologist at Shrewsbury hospital who had the temerity to call into question - at a medical conference in America - the conduct of trials of a heart implant device. Certain of the researchers involved in them were paid consultants of and/or had financial interests in the Corporation which manufactures them. Although he could not realistically be sued in America, in view of the constitutional right to free speech, he is now being sued in England despite the tenuous link to this country - plaintiffs have only to show minimal publicity here and do not even have to show any actual financial loss here. [Click here for the updated position] And in this country, if you accuse someone of something unpleasant, like lying, then it is up to you to justify your accusation. In most other countries, including America, the person objecting to the accusation must prove it to be unfounded. And, of course, our system of exaggerated damages and costs makes the game of libel one which only the rich can play. For a normal person to get involved can be ruinously expensive - win or lose. Simon Singh has so far run up a bill of £200,000 in legal costs. How much the BCA has clocked up we do not know, and normally, the loser pays most of these. Simon Singh, fortunately, is a successful author and can just about afford the risk. Most cannot and so they are silenced.

The law is ripe for a change and the major political parties seem to be in favour of this, but nothing so far has happened. But now the Court of Appeal has brought us some hope. Simon Singh appealed and, most unusually, the Court of Appeal decided to field its top team - the Lord Chief Justice, the Master of the Rolls and Lord Justice Sedley. From time to time, the Court obviously decides that a matter is so important that change is needed. And change has come. In a judgement which alluded to Orwell's Ministry of Truth and Milton's report of the deadening effect of the Inquisition on scientific thought in the middle ages in Italy, they overturned everything which Mr Justice Eady had decided. They came to the conclusion that the Courts were an inappropriate forum for deciding scientific truth. They asked how a court could possibly decide on something which is a matter of debate in the scientific community. Even though they made no reference to the point that in science nothing can ever be verified, they decided that what Simon Singh had said was not verifiable fact, but opinion, and so he had available a defence of 'honest comment'. As for the Mr Justice Eady's finding that "happily promoting bogus treatments" meant that the BCS was necessarily being accused of lying, this they rejected completely - which Simon Singh had said all along was never what he meant.

But amongst the evidence put forward by the BCS was a trial of treatment of infantile colic by manipulation amongst 316 children. They said:

This ... measured the number of hours each child spent in crying. It showed a reduction in crying time from 5.2 hours each day to 0.65 hours each day at 14 days. This was a very substantial improvement. There was no control group. However, the study constitutes evidence.

But does it? The Court of Appeal said

To a literalist, any primary fact for example, that following chiropractic intervention a patient's condition improved may be evidence of a secondary fact, here that chiropractic works. To anyone (and not only a scientist) concerned with the establishment of dependable generalisations about cause and effect, such primary information is as worthless as evidence of the secondary fact as its converse would be.

Duchamp told us that his urinal was art when it was taken from its usual place on the toilet wall and hung instead on a gallery wall. It had gone beyond being simply a rather unimaginative design accompanying our everyday lives. But evidence should not be amenable to such self-serving treatment. Evidence, to be classified as evidence, should provide real support for a view and not just be consistent with it. Correlation does not equal cause. The word evidence should not be manipulated, whether by Humpty Dumpty or by Chiropracters, so that it means what they want it to mean.

P.S. The BCS has now decided not to appeal against the court's decision and has filed a notice of discontinuance.