Card counting itself is not illegal under Nevada gambling laws, but it is considered a felony to use devices to help count cards. The Nevada Gaming Control Board sent a memo to casinos last week warning them of the program.
In blackjack, certain card counting techniques help players determine when they are likely to win a hand and adjust their bets accordingly. Nevada learned of the program from gambling regulators in California, where officials at an Indian casino found customers using it and tipped state authorities.