Vegas casinos (or any other casino) do not "outlaw" card counting. As long as you are not caught, you can count all day long. However, since a Casino is a private business and no one has a "right" to be there, you can be asked to leave and/or be banned for any reason the management wants. They do this in a very professional manner (compared to the old days), often giving a free dinner and room if the counter just stops gambling. This is what happened to some of the MIT team. The MIT team was never arrested or prosecuted for anything and legend has it there is one or another version of the MIT team at work right now (the TV special blacked out the face of a few of the interviewed team members).