Quote Originally Posted by Kralizec View Post
Everybody here seems to agree that if there's sufficient evidence they committed crimes of some sort (i.e. aiding an armed insurgency against a recognised government) they'll have to face charges. If there's no evidence of this sort, you can't really do anything. I'm not sure what your problem is.

I suppose you could invent a criminal offence for people like Brenus mentioned, who only travel there because they want to live in rebel-held territory and willingly associate with them in some way. But I foresee trouble with coming up with a definition that excludes journalists and humanitarian workers (not really relevant in the case of IS, but moreso for other conflict zones). And creating a new criminal defintion obviously won't apply to current cases.
All western citizens who wish to remain western citizens should not travel to the Islamic State. Anyone who is found there can be assumed to either a sympathiser of said state, in which case they can give up their western citizenship and become a citizen of the IS. Or they are travelling there on their own accord. In which case, hand them over to the IS and let them do with them as they will. If they want to get along, let them become citizens of that state, while if they don't want to get along, wash our hands of them. The only exceptions are anyone explicitly and formally authorised by a western government, signed off by the head of the government so there can be no argument.