What is hate speech? Who defines it? Who decides if it should be punished or not? An Australian, Frederick Toben, has been arrested in London as German courts seek his extradition. In Germany, he has been accused of Holocaust denial, a crime that could inspire others to reawaken Nazism. He and his supporters, like David Irving and the Lib-Dem MP, Chris Huhne, say he should not face his accusers in Germany because Holocaust denial is a question of freedom of expression. In Los Angeles, two British citizens, Simon Sheppard and Stephen Whittle, are also in police custody. They were convicted this summer by Leeds Crown Court of publishing anti-Semitic and racist material. They skipped bail and flew to the US hoping that the authorities there would defend their right to freedom of expression.

There is a separate question of whether courts in one country can ask for the extradition of people to reply to accusations over crimes that may not be considered as such in the original country. The European Arrest Warrant allowed one of the 7/7 accused terrorists to be sent speedily back from Rome. By contrast, before the EAW was introduced in 2003, an Algerian Islamist, Rachid Ramda, accused of financing the 1995 Paris Metro bombing, was able to resist extradition from Britain to France for 10 years before being returned in 2005. He is now serving a life sentence.

However, there is not a settled liberal view on crimes like Holocaust denial. British libel laws are notorious for attacking free expression. Equally, British tabloids destroy families through invasions of privacy merely to boost circulation. Each democracy has its own interpretation of where the boundaries of absolute free expression lie. Even in the US, there is no right to cry "Fire" in a crowded theatre. Britain's race-relation laws going back to earlier public-order acts do not allow speech and publications that stir up hate against black or other ethnic minority citizens.