The science writer Simon Singh is fighting to defend his right to freedom of speech. And he's far from alone as companies from around the world are increasingly trying to use England's libel laws to quash academic critics

Earlier this week, a mild-mannered freelance science writer stood on the steps of London's imposing Royal Courts of Justice and declared his determination, come what may, to stand up for free speech against what he and an ever-swelling contingent of scientists, public figures and celebrities believe is the oppressive burden of the UK's libel laws.

Simon Singh, science writer and co-author of a book about alternative medicine, provoked a libel suit from the British Chiropractic Association (BCA) ­after a piece was published in the Guardian's comment pages. He may now make history.

In the venerable stone building, three of England's most senior judges listened to his case and are now deliberating over its merits. The line-up of Lord Chief Justice Lord Judge, Master of the Rolls Lord Neuberger and Lord Justice Sedley has led some commentators to believe the issues around ­science writing and libel are suddenly being taken very seriously indeed in ­legal circles. Many hope that the judges' ruling, when it comes, will loosen what they argue are draconian restrictions on freedom of speech.

Singh is still in the early stages of the libel suit, fighting over the meaning of the words he used about the BCA, whom he accused of supporting "bogus" treatments for children. Mr Justice Eady, in a preliminary ruling that ­provoked a storm of protest, ruled that what Singh wrote was fact, not comment, and that to justify it, he would have to prove the association's members were dishonest. Singh says he never ­intended that ­interpretation. The big guns in the court of appeal must now decide whether Eady's interpretation should stand.

Amid all the outrage over the use of superinjunctions by companies such as Trafigura to try to prevent media and even parliamentary discussion of ­attempted legal gags, attention has turned to attempts to silence ­scientists. Singh is by no means waging a lone battle.

In October 2007 in Washington DC, a heart expert from Shropshire had an earnest conversation with a reporter from the little-known US medical website Heartwire. The reporter, Shelley Wood, could see that if what Dr Peter Wilmshurst was saying was true, she had an important story on her hands. Wilmshurst had designed a trial for a Delaware-based company called NMT Medical, to find out whether closing small holes in the heart using their ­device would stop people suffering from migraine headaches. But the UK trial, christened Mist 1, was a failure: the migraines did not go away – and Wilmshurst, who was strongly critical of the conduct of the research, had a theory as to why.

He suggested that the problem might be not with the concept but the device itself. Although it had been ­implanted in tens of thousands of ­people, it was possibly not as effective in closing holes as had been thought. Two years later, he is facing a libel ­action in the English courts brought by the device manufacturer, NMT Medical, that could lose him his home.

Wilmshurst, who has a history of whistle-blowing, is the sort of doctor who will never back down. He says he believes NMT has "got themselves in out of their depth. I don't have any money. I have got half a house and no other money." The campaigning group Healthwatch has started a fund to pay his legal costs. "It is an important issue," Wilmshurst says. "The English high court is being used to silence people. I gave a lecture in America that was picked up by a medical journalist there, and she put something on a website. Yet the website and the journalist are not being sued."

NMT Medical denies it is sueing in England because of the tough UK libel laws: "This case is not about libel ­tourism at all," says its chief operating officer, Rick Davis. "Our suit was not brought in any way because of any ­scientific views that Dr Wilmshurst holds. He has accused NMT of research fraud, and we believe he did that maliciously."

For Wilmshurst, this is not just a question of freedom of speech, but public access to information. He is ­angry that he and a colleague working with him at the Royal Shrewsbury ­hospital were not allowed to see the detailed "line" data (as opposed to summaries) to work out why the trial failed to alleviate migraine. "These things are important; we learn from what we publish. Someone else may come along and design a study that is flawed because they haven't been given the full information from other studies, and it may put patients at risk."

Many of the scientific libel cases are in the medical field – probably because of the strong passions the needs of ­patients evoke, and the big money to be made from new treatments. And while Wilmshurst went beyond the normal academic cut-and-thrust of weighing and debating evidence with other scientists, the Liberal Democrat MP Evan Harris says libel blight is now threatening even scientists who merely publish the results of their investigations in respected (and peer-reviewed) ­scientific journals.

These journals offer rights of reply, discussion columns and have corrections policies. They have high standards of proof and are held in high regard within the scientific and academic world. And yet, say many of their editors, they too feel direct or insidious pressure from corporations and groups with vested interests not to publish papers that might prove damaging. "It is what is not published or has to be omitted ­because of a lawyer's letter," Harris says. "I support Peter Wilmshurst and the many other cases currently being fought, but the biggest problem has ­always been the stuff that doesn't even get published because of the fear."

Harris says peer-reviewed journals should have an automatic public interest defence if they are accused of libel, or should enjoy some sort of qualified privilege. After all, scientists have ­always played a critical role in the monitoring of complex technological and medical advances. Fifty years ago, it was a whistle-blowing scientist, Frances Kelsey, who stood up to ­pressure from the manufacturer of Thalidomide and ­refused to approve a licence for the drug in the US. She wanted more proof that it would not harm the foetus, and was proved horribly right in her suspicions when hundreds of ­deformed babies began to be born in Europe. Today's embattled scientist may be tomorrow's hero.

Another case currently arousing concern involves Swedish linguistic and phonetics experts ­Francisco ­Lacerda and Anders Erikkson, who in 2007 wrote a paper criticising the ­technology used in lie detectors. ­Published in the UK by the highly ­specialised, peer-reviewed International Journal of Speech, Language and the Law (IJSLL), they alleged that, ­scientifically, the "layered voice ­analysis" technology in lie detectors currently being trialled by UK local ­authorities trying to catch benefit cheats is "at the astrology end of the spectrum".

Lacerda and Erikkson are not being sued by the Israeli manufacturer, Nemesysco. Swedish law would not ­allow them to be sued in Sweden, but the British publishers of the paper, Equinox, withdrew it ­under the threat of a libel suit in the English courts. Janet Joyce, managing ­director of the IJSLL, preferred not to talk about the crisis, saying she had "decided not to revisit that dreadful experience again". But Lacerda was a lot more forthcoming. "We thought it was in our mission as scientists to ­disclose this type of thing – to explain why it can't work," he said.

They included a direct ­attack on the company and the ­credentials of the ­inventor of the ­technology, Amir ­Liberman. Lacerda admits it was "a little bit on the edge for a scientific paper", which had the take-no-prisoners title, Charlatanry in Speech Science: A Problem to Be Taken Seriously. Nonetheless, support for Lacerda and Erikkson has been vocal, particularly in Sweden where the law is more liberal than in the UK. In May, the Royal Swedish Academy of Sciences stated: "Incidents of this kind are a threat to research freedom and, by extension, to the free dissemination of information in society. Threats to sue must not be used to restrict scientific discussion."

Liberman, the device's inventor, takes a different view. He tells me he would not have resorted to law if ­Lacerda and Erikkson had stuck to ­science. "Now," he says bitterly, "if you research my name on the internet, after the first few items you find I'm a charlatan. What a great legacy for my kids."

Ironically, his legal action has brought the Swedish paper far more attention than if he had never threatened to sue. But Liberman assures me that, according to the English legal ­system, there is a clear case of defamation. "We can certainly press charges. Scientists should be more ­concerned about the way they treat others: their word is taken at more than face value because they are scientists."

This is precisely why libel reform campaigners such as Index on Censorship and the Libel Reform Campaign – which counts writers, artists and entertainers among its supporters, from Jonathan Ross to novelist Monica Ali to comedians Stephen Fry and Shazia Mirza – wish to take up the cases of ­scientists. And the publicity the cause has been attracting may already be forcing companies to think twice.

Last week, GE Healthcare dropped its libel suit against Henrik Thomsen, a Danish radiologist at Copenhagen University who had publicly linked one of its drugs to a chronically disabling condition, saying that it did not mean to stifle academic debate.

Thomsen had given a presentation to a small group of doctors and scientists at the Randolph hotel in Oxford in 2007. He was anxious to warn them of the potential dangers of a drug called Omniscan, given routinely to kidney patients to enhance MRI scans and make them easier to read. Twenty ­patients at his university hospital had developed nephrogenic systemic ­fibrosis (NSF), a condition in which the skin swells and tightens. Some ended up in wheelchairs as a result, and one died. Thomsen and his colleagues ­believed the drug, which contained a toxic metal called gadolinium, was directly linked to the incapacitating ­illness of their patients.

In an agreed statement last week, he reiterated his view that Omniscan was to blame. "I stand by my publicly ­expressed opinion, based on my ­experience and research on published papers, that there is an association ­between the chemical formulation of gadolinium-based contrast agents and NSF," he said. But Thomsen added he had never intended to suggest GE Healthcare had marketed the drug knowing it might cause NSF. This, said the company, was the reason for the ­libel suit. "GE Healthcare objected to statements made by Professor Thomsen which it interpreted as suggesting it had known from the outset that ­Omniscan caused NSF," the company said, while welcoming "a principled debate" over safety issues.

Thomsen will be much relieved. The cost and the time libel actions take make them prohibitive for most people. Singh has already spent well over £100,000 on his own defence, and the bestselling science writer and broadcaster admits he is better able to afford it than most people.

The costs of libel cases regularly reach hundreds of thousands of pounds – often far exceeding the payouts. "A libel ­tribunal would be one solution," Singh suggests. "And that goes for both sides. If the BCA lose this case, it is going to be horrific for them. If people want to sue for libel, that's fine, but it shouldn't be so traumatic or expensive."

Padraig Reidy, of Index on Censorship, agrees there is a need for defamation laws: "Special pleading for medical and science writing is neither desirable nor implementable," he says. But in his view, medical and science writers would be sufficiently protected if the UK was to introduce a stronger public interest defence – one strand of a 10-point strategy that Index and other libel reform groups are proposing.

"The case of Peter Wilmshurst presents a perfect storm of the problems with England's libel laws," Reidy says. Wilmshurst is "a man being sued for a quote published on a website that should be outside English jurisdiction, by a company very few people had ever heard of, who now says he could be ruined for speaking out in the public interest as he saw it".

The Libel Reform Campaign appears to be making headway. Its leaders are in discussions with the Ministry of ­Justice (Jack Straw has set up a working party), and the House of Commons ­culture, media and sport select ­committee has just proposed measures to limit libel tourism, boost the public-interest defence, cut costs and require corporations that sue individuals to prove actual damage to business.

Any changes will come too late for Singh, Wilmshurst and others with cases already lumbering along – but ­scientists of the future may find it a ­little easier to speak their minds.