What happens when the free pursuit of answers in scientific research comes face to face with English law? Alan Urry investigates.

Simon Singh, author of Fermat's Last Theorem and The Code Book, is one of the UK's most successful science writers.

Peter Wilmshurst is a respected cardiologist and has long fought for high ethical standards in scientific research.

Francisco Lacerda works in Stockholm studying how children learn to speak.

Henrik Thomsen is a Danish radiologist with an interest in kidney disease.

They are a disparate group, but what they all have in common is that they have all fallen foul of English law for engaging with what they believe are scientific debates.

Lawyers, journalists and scientists are now campaigning for a change to the UK libel laws to protect free speech.

Those issuing or threatening the writs say they have commercial reputations to protect.

Where should the balance lie?

Allan Urry investigates what happens when writs meet scientific debate.