Generally, it is dissenting writers, artists and journalists who find themselves hounded by libel lawyers acting for rich and powerful clients, not to mention prickly faith groups and vested political interests. But, increasingly, scientists are becoming a target of legal bullying as big businesses use the threat of costly defamation action to gag critical voices and stifle academic debate.

There is concern that some sort of self-censorship has already started to creep in with science journals and websites preferring not to publish potentially controversial research papers to avoid legal hassles.

Leading British scientists, including a former government chief scientific adviser, David King, are among the nearly 19,000 academics, writers and journalists who have signed a petition calling for science to be taken out of the purview of the country’s libel laws.

The petition, initiated by Sense About Science, an independent charity which works with the scientific community, says that current libel laws have a “chilling effect” on free speech. They “deter” scientists and science writers from engaging in “argument and debate” on matters of public interest.

“Freedom to criticise and question in strong terms and without malice is the cornerstone of scientific argument and debate, whether in peer-reviewed journals, on websites or in newspapers, which have a right of reply for complainants… [but] libel laws discourage argument and debate and merely encourage the use of the courts to silence critics,” it says arguing that defamation laws have “no place” in scientific disputes.

The campaign was triggered by the case of Simon Singh, a British-Indian science writer and Bafta-winning broadcaster, who is being sued by the British Chiropractic Association (BCA) over an article in which he claimed that chiropractic treatments for illnesses such as asthma and ear infections were not backed by scientific evidence.

The BCA has been accused of trying to “silence” criticism of its practices by resorting to legal action instead of defending its position through public debate.

In another similar case, a leading British scientist has been sued by an American company for questioning its claims about the effectiveness of a heart device. Peter Wilmshurt, a consultant cardiologist at the Royal Shrewsbury Hospital, made the comments in a lecture at a cardiology conference in Washington two years ago.

Dr. Wilmshurt, angry that remarks made during the course of an academic discussion can become the basis of libel action, says that he will use “public interest” defence to argue his case and will not agree to an out-of-court settlement unless the company which is suing him recognises his right to criticise scientific research.

“I have got a responsibility to fight this. It makes me rather more angry that the law can be used in this way to suppress information that may be in the public interest for us to know. There is a fundamental principle of science at stake here,” he argues.

The Singh and Wilmshurt rows feed into the larger debate on Britain’s libel laws which are heavily weighted against the defendant or — in the words of one newspaper — “unique in the burden of proof that they impose on a defendant”. More controversially, they allow cases to be pursued in British courts even if the alleged defamation has taken place in another country and the defendant is neither a British citizen nor a resident. It is enough for the allegedly libellous comments to appear on a website in Britain to justify legal action in a British court.

This, campaigners point out, has turned London into the “libel capital of the world” with foreigners who cannot sue in their own countries flocking to Britain to file cases. Sir Ken Macdonald, a former Director of Public Prosecutions, has warned that Britain is in danger of becoming an “international haven for people to attack scientists”.

It has also become an issue across the Atlantic with Washington reportedly considering plans to legislate against enforcing damages awarded by British courts in cases not deemed defamatory under American laws. In a strongly-worded editorial, The Times said that it was “grotesque and shaming” that a democratic ally such as America needed to “protect the liberties of its own citizens from assaults emanating from the mother of parliaments”.

A report by Index on Censorship and English PEN, the writers’ campaign group, has called for a thorough review of British libel laws which, it says, impose “unnecessary and disproportionate restrictions on free speech” and do “not reflect the interests of a modern democratic society”. They have encouraged “libel tourism” and spawned jokes about London which some refer to as a “town named sue”.

The report makes a series of recommendations including a ban on cases being brought to London unless a publication in which an allegedly libellous article was published has at least ten per cent of its circulation in Britain.

Meanwhile, the government has been accused of muzzling scientists after Home Secretary Alan Johnson sacked his chief drugs adviser David Nutt for criticising government policy on classifying drugs. Three of Prof. Nutt’s colleagues resigned in protest. Their point was that the government must stop treating scientists who work for it like automatons and instead respect their independence and the right to express their views even if the Home Secretary does not like them.

Elementary, Mr. Johnson?