Home Secratary Theresa May has issued an exclusion order for the controversial Muslim preacher Zakir Naik.

At first glance this is similar to the ban on Dutch MP Geert WIlders imposed when he was due to show his film Fitna in the House of Lords last year. The ban on Wilders, whose film juxtaposed verses from the Koran with images of terrorist atrocities, backfired on two counts. First, it simply made him a free speech martyr and drew attention to his scare-mongering views that were freely available on the Internet. Secondly, it wasn’t sustainable — Wilders won an appeal against the ban at the Asylum and Immigration Tribunal. In retrospect (and as it seemed at the time too) it would have been far better to have let Wilders have his say, and to have met his arguments with counterarguments and evidence. I made a podcast about this criticising the Government action at the time (Listen here)

Does that mean that on free speech grounds we should discourage the UK Government from imposing a ban on Naik? Here’s a possible difference between the cases: Naik has reputedly expressed sympathy for Osama Bin Laden’s terrorism and seems in some of his pronouncements to be advocating actual violence against Americans and against those who change their religion.

If that is correct, then there may be good reason for a ban. The most obvious acceptable limit to free speech is the point at which a speaker incites violence. Yet, the situation gets more complicated. Naik has issued a press release in which he “unequivocally condemns acts of violence including 9/11, 7/7 and 7/11.”

So, should we take the press release as a sincere statement of his current position? If so, is it reasonable to ban him for views that he has apparently jettisoned if indeed he ever held them? This is not an easy case to decide. Perhaps allowing him to speak in Britain while monitoring closely the content of his oratory will in the end be the least worst option.