As far as I understand it, keeping certain corals collected outside the country is illegal. Mind you, like many things that are illegal here, the relavant authorities turn a blind eye to it so long as they get their cut. My knowlege of this matter is limited though.
I havent heard of anyone keeping imported corals getting in trouble with the law, just the people bringing them into the country and selling them on.
It is crazy that we dont farm corals and export them from here, but again the law/political self interest stuffs it up.