A galaxy of luminaries from the disparate worlds of science, comedy, the arts and humanities – from Ricky Gervais to the president of the Royal Society – have come out in support of a science writer who is being sued by chiropractors for saying they practise "bogus treatments".

Dr Simon Singh allegedly libelled the British Chiropractic Association (BCA) in an article claiming the association is the respectable face of the chiropractic profession and yet it happily promotes "bogus" therapies. The BCA demanded an apology and a retraction, and in its libel action won a preliminary court ruling against Dr Singh last month. In it, Mr Justice Eady ruled that Dr Singh's use of the word "bogus" meant he was accusing the BCA of being dishonest and backing treatments it knew did not work. He refutes this, saying that "alternative therapists who offer treatments unsupported by reasonable evidence are deluded rather than deliberately dishonest".

Dr Singh announced yesterday that he intends to appeal against the ruling, which has already cost him about £100,000 in legal fees but won him the backing of more than 100 prominent figures – including a Nobel laureate.

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The signatories to the statement in support of Dr Singh include Gervais, the actor Stephen Fry, the scientist Richard Dawkins, Lord Rees of Ludlow, president of the Royal Society, former government chief scientist Sir David King, the novelist Martin Amis and the comedian and doctor Harry Hill. "We, the undersigned, believe that it is inappropriate to use the English libel laws to silence critical discussion of medical practice and scientific evidence," the statement reads.

"The English law of libel has no place in scientific disputes about evidence. The BCA should discuss the evidence outside of a courtroom."

Yesterday, Dr Singh's supporters spoke out against the BCA's decision to launch legal action against an individual with no financial support. "When a powerful organisation tries to silence a man of Simon Singh's reputation [he was made an MBE in 2003 for services to science] then anyone who believes in science, fairness and truth should rise in indignation," Mr Fry said.

Professor Dawkins added: "The English libel laws are an international laughing stock, and the effects are especially pernicious where science is concerned." While Sir David said: "It is ridiculous that a legal and outmoded definition of a word has been used to hinder and discourage scientific debate. We must be able to fairly and reasonably challenge ideas without fear of legal intimidation. This sort of thing only brings the law into disrepute."

Chiropractice is the quasi-scientific treatment of medical problems by manipulating the spine, although many disorders treated by chiropractors are not normally associated with a bad back. One of its information leaflets, entitled Happy Families, says: "There is evidence to show that chiropractic care has helped children with asthma, prolonged crying, breathing difficulties, bed-wetting, colic, sleep and feeding problems, hyperactivity [and] frequent infections, especially in the ears."

Dr Singh's article questioned the scientific evidence to support such a statement, saying that he can confidently label the treatments as "bogus" because he has researched them while working on a book on alternative medicine with Professor Edzard Ernst of Exeter University, the world's first professor of complementary medicine.

The BCA said that it intends to pursue its claim against Dr Singh, who replied by saying that if his attempt to appeal against the preliminary ruling fails, he will take his case to the European Court of Human Rights.

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Strange world of the father of chiropractice

* Chiropractice is the manipulation of the spine to treat a range of problems not associated with a bad back. It was invented by Daniel David Palmer of Davenport, Iowa, at the turn of the 20th century after he claimed to have cured an office janitor, Harvey Lillard, of deafness by "racking" his back. Palmer, known as "DD", said that Lillard had been deaf for 17 years after he had strained his back. "I reasoned that if that vertebra was replaced, the man's hearing should be restored," he said. "I racked it into position by using the spinous process as a lever and soon the man could hear as before."

* After an unsuccessful earlier career in "magnetic healing", Palmer switched to spine manipulation, which his close friend the Rev Samuel H Weed called chiropractice after the Greek words for "hand" and "practice", meaning "done by hand".

* Palmer wanted to turn chiropractice into a new religion, with himself at the helm, and openly likened himself to Martin Luther, Mohamed and Christ: "I am the fountainhead. I am the founder of chiropractice in its science, in its art, in its philosophy and in its religious phase."

* He practised racking the spines on his many children – he was married six times – and his over-enthusiasm with physical punishment sometimes landed him in trouble with the police.

* Palmer died in 1913 after being run over by a car allegedly driven by one of his sons, Bartlett.