dont ask that question...al never stop askin it my self.......me n my chums are addicted!, as im sure craig will know!
lol
if i was you, i would NOT listen at all, as im ver very much sure it is illegal!, but its entirely up 2 u wat u do!
Jimbo, you'll get an ulcer worrying about this while at the same time listening because you enjoy it so much. Contact the proper authorities (anonomously, if you like), and ask them. Or if you can speak to a controller (call a control tower or control center, contact their union, whatever), I'm sure they'll give you the low-down. Tell them that you'd just like to listen (and learn). Law or no law, there's no harm in listening, when you think about it.
Monitoring law-enforcement bands could certainly be useful for criminals, but unless you're transmitting, you're not going to interfere with ATC operations by listening . Military bands? Might be a different story, but knowing how many receivers there are out there, I'd imagine the military would rely on code names, etc. to conceal details of operations, and if I'm not mistaken, most scanners don't pick up on the bands the military uses.
I've heard of cases where people have caused problems by talking on ATC channels (could be dangerous!), but never heard of anybody getting in trouble for listening. I've been doing it for years, and so far no knock on the door in the middle of the night...
Anyway, don't look for the answer here. Ask the authorities, or the controllers themselves.