Richard Dawkins, the evolutionary biologist, is to call for Britain’s libel laws to be reformed following a string of cases in which science researchers and writers have been sued for criticising health therapies they felt to be unreliable.

Dawkins will today ask Nick Clegg, the Liberal Democrat leader, to support reforms that would protect scientists and doctors who want to speak out against treatments they have concerns about.

Among those currently facing writs is Simon Singh, the broadcaster and author, who is being sued by the British Chiropractic Association for an article criticising the use of chiropractic techniques for some childhood illnesses. He has spent £100,000 defending the action.

Another is Peter Wilmshurst, a heart specialist at Royal Shrewsbury Hospital, who is being sued by NMT Medical, an American company, for suggesting that medical trials into one of its devices had been described innaccurately to other scientists.

Wilmshurst made his remarks in America to a US journalist who published it on an American website. However, the company was still able to issue its writ in Britain, where libel laws are regarded as among the most draconian in the world.

Dawkins will tell the Lib Dem conference in Bournemouth that the UK’s libel laws are having a “chilling effect” on public debate about science and medicine.

He is expected to say: “England’s libel law is being ridiculed as an international charter for the litigious. I urge politicians to support the call for reform so we can get cross-party support on this vital issue.”

Dawkins, who is not a Lib Dem member, was invited to speak by Dr Evan Harris MP, the party’s science spokesman. Harris said: “It is shameful that London is regarded as the ‘libel capital of the world’, where claimants from around the globe can use our antiquated libel laws to silence criticism.”

The campaign to change Britain’s libel laws has won widespread support. Sile Lane of Sense About Science, which is co-ordinating the Keep Libel Laws out of Science campaign, said the same plea would be made to the upcoming Labour and Conservative conferences.

She said: “English libel law is having a stultifying effect on important public discussions and has become dangerous and intolerable.”

Singh, who gained a PhD in particle physics before becoming a science documentary producer and author, has been a strident critic of alternative therapies such as homeopathy and chiropractice, suggesting there is no evidence to show they work.

Singh said: “This case has dominated my life for a year and cost a great deal of money but I was not criticising any individual. I was raising an issue of great public importance.”

Wilmshurst said: “I believe its wrong that the English libel laws can be used to silence scientific debate, especially when it has implications for patient safety. I have lived with this libel action for nearly two years and it has had an enormous financial and personal cost.”

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