Most people only know about counting cards because of movies like Rain Man and, more recently, The Hangover. For that reason, there are a lot of misconceptions about card counting. The most common question I get about it, aside from how to do it, is whether or not it’s legal. The short answer: yes, sort of.
Before I get into the “sort of” part, I need to point out something. Casinos hate card counters. Fair or not, if they catch you counting cards, they will escort you from the casino and may even ban you from visiting again. If it’s a casino chain, you could be banned from every casino they have. If you get kicked out of enough casinos for counting cards, you could find yourself blacklisted and unable to play anywhere in the state. All of this is despite the fact that you wouldn’t have broken any law.
There are currently several legal battles over whether the casinos have the right to do that. Players contend that if the casino offers a game involving skill, they shouldn’t penalize people who are more skilled than others. The casinos contend that, as private businesses, they have the right to refuse service to anyone. Both arguments make good points, which is why I don’t think the issue will be resolved anytime soon. So for now, the answer is that card counting is legal but can still get you banned from a casino.
There is a caveat, though. It is legal to use your mind only to count cards. No external device of any kind can be used to help you. That includes obvious things like digital counters, calculators, surveillance and other high-tech equipment, but it can also be very low-tech. If you wrap a rubber band around your finger and move it around while counting, that’s illegal. If someone else counts for you and somehow relays the information to you, that’s illegal. Writing it down is illegal (though that would also easily be caught). Any trick that you can possibly think of that requires anything other than the internal processes of your mind would make card counting illegal. And if you count cards illegally, you are going to get a much worse fate than getting tossed from a casino.