Yeah, pointing powerful lasers at the sky runs the risk of causing a plane crash. Don't do that, people.
My brother bought a laser while on a school trip to... somewhere abroad in Europe... can't remember where. Anyway, it got confiscated at the border. I don't think I ever knew exactly why, he wasn't really old enough to kick up a fuss and question it (or do I mean wasn't foolish enough? I suppose that depends on which border it was).