Holocaust denial is of course appalling behaviour and I'd quite happily describe Toben as being, in my opinion, a scumbag for putting the view forward. However, as Nigel notes, there's another side to this:
Campaigners are also concerned that the UK is assisting the extradition of someone whose views appeared on the internet - rather than being published in Germany itself.
Nigel Farage, leader of the UK Independence Party, said that while his party in no way condoned Dr Toben's views, "not only has he not broken any UK laws, but in seeking to arrest him, Germany is claiming censorship rights to the entire internet network."
This view is shared by Australian free-speech campaigners who have accused Germany of trying to "legislate for the entire world" by treating downloadable internet material as a German publication.
As far as we can all tell the claim is that whatever he put on his website in Australia is subject to German law. Are we really certain that we want a system like this? That anything you or I write on the net must conform to German law? Or French, Italian, Greek, Slovenian or Lithuanian? That's what the German claim amounts to.
This is one of the basic problems of the European Arrest Warrant. That it abandons the idea of double criminality. That is, you can only be extradited from a place if what you're being accused of is a crime both in the place you're in and the place doing the claiming.
Holocaust denial isn't a crime in the UK. Thus the whole issue would simply not exist if we didn't have this EU warrant.