"Black Book" is the nickname frequently used to refer to a list of persons who are unwelcome in casinos. The name comes from the fact that the persons listed in the "book" are essentially "blacklisted". The term can refer either to such a list officially maintained by a particular Gaming Control Board, or to the Griffin Book, whose information is shared between casinos.
In the former case, persons listed are generally suspected of having, or known to have, ties to organized crime. Casinos are obliged by regulations to exclude all such persons from entry, and can be subject to sanctions from the Gaming Control Board for failure to do so.
In the Griffin Book, published by Griffin Investigations, listed individuals are generally suspected of being, or known to be, either advantage players or outright cheaters at the casino games themselves. Thus, casinos find it in their own economic best interest to exclude such individuals. Those listed may be anyone perceived as a threat to the casino's profits, including those that use legal and illegal means, such as card counters, people who mark cards, those who try to cheat slot machines or anyone else considered a threat to a casino, including players that the casinos believe are winning too much or too often. The book keeps pictures either obtained from a photo of the individual when detained or simply questioned and released or from surveillance photos. At least one successful defamation lawsuit has been brought as a result of the Griffin Book.[1]