Interestingly, tapping in on mobile phone conversations, and de-scrambling them, is legal in Norway, at least for the state. AFAIK they still don't need a court ruling to do so, like they do when they want to wiretap someone. This is because the radio waves aren't regulated the same way as wired connections in Norway. I suspect this might be similar in the rest of the EU as well (of which Norway is merely a de-facto member). It might also be something to look into if you're an American, to check whether this is also reflected in either federal or state laws.