Counting cards in blackjack has become substantially more difficult as a result of casino countermeasures. The most common is the use of more decks, which decreases the player’s advantage, but even in the few remaining single- and double-deck games, dealers will often shuffle prematurely or unusually frequently to defeat a suspected card-counter. However, for the casinos there is a downside to frequent shuffling: It reduces the amount of time that the noncounting players are playing and consequently losing money to the house. It has become common for casinos to use automatic shuffling machines to compensate for this. Some models of shuffling machines shuffle one set of cards while another is in play. Others, known as Continuous Shuffle Machines (CSMs) allow the dealer to simply return used cards to a single shoe to allow playing with no interruption. Because CSMs essentially force minimal penetration, they remove almost all possible advantage of traditional counting techniques. As a result, some blackjack players call for a boycott of tables using CSMs. In the case of online casinos, the deck is shuffled at the start of each new round, ensuring the house always has the advantage. However, some online casinos periodically animate the dealer shuffling the cards to give the illusion that the cards are shuffled infrequently.
Unfavorable rules can cut into a player’s advantage, such as no double down after splitting, and having the dealer hit a soft 17 (ace, six which can play as 7 or 17.) Starting around 2004 a number of casinos began offering a 6:5 payoff on player blackjacks instead of the more traditional 3:2 payoff. These games are generally single-deck, inviting unwary card-counters and other players who believe they have an advantage. The inferior payoff substantially increases the house edge and makes the game unbeatable, even by a card-counter who is practicing the most sophisticated system perfectly.
A pitboss who determines that a player is a card-counter might either “back off” the player by inviting him/her to play any game other than blackjack, or will ban him/her from the casino itself. In jurisdictions where this is not legal, such as Atlantic City, a pitboss can require the player to flat-bet and disallow players from entering in the middle of a shoe. Such countermeasures effectively remove any chance of gaining an advantage from card counting in multi-deck games. The player’s name and photo (from surveillance cameras) may also be shared with other casinos and added to a database of card-counters and cheaters run for the benefit of casino operators. One such blacklist was known as the Griffin Book, and was maintained by a company called Griffin Investigations. However, the Griffin Agency was forced into bankruptcy in 2005 after losing a libel lawsuit filed by professional gamblers.
Many casual card counters make small mistakes that cost the advantage they gain by counting. Two or three mistakes per hour may give back all of the counter’s advantage. Even if one can count perfectly when practicing at home, it is much more difficult in an actual casino. The loud, distracting environments of most casinos, and even the availability of complimentary alcoholic beverages, play roles as casino counter-measures.
Casinos look out for known card counters, who may be banned from play depending on regulatory commission rules. They also look for suspicious actions such as a long series of small bets followed by large one. Monitoring player behavior to assist in this identification falls to on-floor casino personnel (“pit bosses”) and casino surveillance personnel who may use video surveillance (“the eye in the sky”) as well as computer analysis to try to spot playing behavior indicative of card counting; early counter-strategies featured the dealer learning to count the cards themselves to recognise the patterns in the players. In addition, many casinos employ the services of various agencies, such as Biometrica, who claim to have a catalog of advantage players. If a player is found to be in such a database, he will almost certainly be stopped from play and asked to leave regardless of his table play. For successful card counters, therefore, skill at “cover” behavior to hide counting and avoid “drawing heat” and possibly being barred, may be just as important as playing skill.
Casinos may alter the game’s dynamic against card counters by raising the minimum or lowering the limit on a table with a suspected counter, or by reshuffling sooner than the normal end of the shoe if they think that the player is offering a large bet on a positive count.
There have been some high-profile lawsuits involving whether the casino is allowed to bar card-counters. Essentially, card-counting, if done in your head and with no outside assistance from devices such as blackjack computers, is not illegal, as making calculations within one’s own mind is not an arrestable offence. Using an outside device or aid, however, was found illegal in a court case in Nevada involving Keith Taft, a professional gambler known for his innovations in blackjack computers and other gambling technology. In this case, two members of Keith Taft’s team were convicted of cheating for using a video device to gain knowledge of a blackjack dealer’s hole card. At the time of the Taft team trial, however, there was no anti-device law in Nevada, and the law that was written after this case is considered by many attorneys to be unconstitutionally vague. Still, the law has been adopted by most other states with casinos, and no player has yet tried the constitutionality of the law.
Casinos don’t tolerate card counters or practitioners of other legal professional gambling techniques willingly and, if permitted by their jurisdiction, may ban counters from their casinos; in Nevada, where the casinos are ruled to be private places, the only prerequisite to a ban is the full reading of the Trespass Act to ban a player for a year. Some skilled counters try to disguise their identities and playing habits; however, some casinos have claimed that facial recognition software can often match a camouflaged face with a banned one. In the experience of most professional gamblers, this is untrue, and a 2004 book by a Las Vegas casino surveillance director, The Card Counter’s Guide to Casino Surveillance, also declares this assertion to be an overstatement. Approximately 100 casinos in the United States used the Griffin Investigations consulting firm to help them track down and monitor card counters, before the firm’s bankruptcy as a result of a lawsuit for libel filed by professional gamblers.
Other modern technology that has been marketed as an aid in catching card counters includes the MindPlay system and Blackjack Survey Voice software.