are people so dubm, people dont even realise that when you connect to a router it keeps track of your wireless cards id or if you are using ethernet the boards id
you can spoof this but its easy to prove to the police that you didnt do it because 2 people cant have the same id and stay connected (we are not talking about ip here)
so they would have a log of all the devices which requested an ip address from the router for accses to the internet
anyway no encryption is safe, there are ways arround most of them with freely availble tools the only difference between security testers,hackers and people like me is security testers and people like me only do it to systems which we have been allowed full accses over and in most casses have the login code anyway