BBC Radio 4's Law in Action was broadcast on Tuesday, 6 February, 2006 at 1600 GMT.
In a week when free speech and religious offence have been at the forefront of the news, one of the few people in the West imprisoned for expressing their views is the English historian, David Irving. He is due to be tried in Austria later this month on charges of denying the holocaust.
Holocaust denial is a crime in Austria and nine other countries, and the actor Steven Berkoff believes passionately that it should be an offence in Britain too. Perhaps surprisingly, he is opposed by the American historian Deborah Lipstadt.
In 2000, she fought and won a famous libel action brought by David Irving, whom she had described as "one of the most dangerous spokespersons for holocaust denial". She believes laws on Holocaust denial only make martyrs of those prosecuted.
She debates the issue with Professor David Cesarani of Royal Holloway college, London.