Is card counting legal?

Three different questions

Almost all the confusion on this subject comes from "is it legal?" being three separate questions, each with its own answer:

1. Is counting an offence? Not in any of the places covered here. No law forbids a person to think.
2. May the casino bar you for it? That depends entirely on where you are, and this is where the interesting legal differences lie.
3. Where does skill become cheating? At the point where a player stops observing the game and starts interfering with it — with a device, or by manipulating the cards.

Card counting is not cheating, and the difference is one of substance, not wording. Cheating changes the conditions of the game — a swapped card, marked equipment, a hidden device. A card counter touches nothing: they watch cards dealt face up, in front of everyone, and draw a conclusion. That is exactly the casino's difficulty with them — there is nothing to accuse them of.

Nevada: thinking is allowed, a device is not

In Nevada, counting in your head is not a criminal offence. What is an offence, expressly, is using help. Section 465.075 of the Nevada Revised Statutes forbids using, or possessing with intent to use, any computerized, electronic, electrical or mechanical device, or software or hardware, designed or programmed to gain an advantage at a game — including, in the section's own terms, a device that projects the outcome of a game, keeps track of the cards that have been played, or analyses the probability of an event in the game.

The line is sharp: exactly the same count is allowed in your head and forbidden in an app. Using a phone to keep a count at a live table is a crime in Nevada, not a matter of house policy.

What a Nevada casino may do is bar a counter. In Uston v. Hilton Hotels Corp. (1978), Ken Uston, one of the best-known counters in history, sued after being escorted out of a Las Vegas casino. He argued that because Nevada regulates casinos so closely, their exclusion of card counters counted as action by the state. The federal court rejected that as "without merit": a casino excluding a player is private conduct, and state regulation of a private industry does not turn it into state action.

New Jersey: the Uston ruling

The most significant ruling in the field is Uston v. Resorts International Hotel, decided by the Supreme Court of New Jersey in 1982. The same Ken Uston was barred from the blackjack tables at Resorts in Atlantic City because his way of playing improved his chances of winning. He sued again — and this time he won.

The court's reasoning was structural rather than moral: New Jersey's Casino Control Act gives the Casino Control Commission exclusive authority to set the rules of the licensed games, including how they may be played. Because that authority rests with the Commission, the casino itself has no right to bar a player for conduct that is not cheating.

Two qualifications that tend to be left out. First, the court did not decide that such exclusion could never be lawful — only that the Commission had not exercised its authority on the matter. Second, the regulatory response did not favour the counters: rather than permit exclusion, the rules were changed in ways that reduce the edge without throwing anyone out — above all, more frequent shuffling, which limits how deep into the shoe the dealer goes.

Other states: the right to exclude

New Jersey's answer turned on the wording of its own statute, and other states have read theirs differently. In Donovan v. Grand Victoria Casino & Resort (2010), the Supreme Court of Indiana held that a business owner's long-standing common-law right to exclude a customer extends to a casino barring a player for strategies that give the player a statistical advantage — and that Indiana's gambling statute does not take that right away.

So in the United States there is no single answer: counting itself is lawful, devices are a separate and serious matter, and whether a casino may bar you depends on the state.

Britain: where skill ends and cheating begins

In Great Britain, the Gambling Act 2005 makes cheating at gambling a criminal offence (section 42). The Act does not define cheating exhaustively, but it says it may consist in particular of "actual or attempted deception or interference" in connection with the process by which gambling is conducted, or with the game itself. No statute mentions card counting.

The leading case on where the line falls is Ivey v Genting Casinos, decided by the UK Supreme Court in 2017. The professional player Phil Ivey won about £7.7 million at baccarat using "edge-sorting": he had the croupier rotate certain cards so that he could later recognise them by tiny asymmetries in the pattern on their backs. The court held unanimously that this was cheating. The reason is the useful part: the court allowed that merely spotting and exploiting a difference in the cards might not be cheating, but Ivey "did much more than observe; he took positive steps to fix the deck".

The judgment does not discuss card counting. But the distinction it draws — observing the game versus interfering with it — is the one that separates counting from cheating. And the regulator, the Gambling Commission, has said it holds no guidance on the legality of card counting and takes a view case by case.

The rest of Europe

There is no European Union law on gambling. In the European Commission's words, there is "no sector-specific EU legislation in the field of gambling services", and each country organises its own. So the questions above — whether counting is an offence, whether a casino may bar you — are answered country by country, and the only honest general advice is to check the rules where you are.

What a casino can do

Even where counting is completely lawful, the house has a large toolkit — and most of it is practical rather than legal:

• Cut the penetration. Shuffling earlier erases the edge without touching the player. It is the most effective defence, and it is invisible.
• Limit the player. Cap their bet, or forbid raising it in the middle of a shoe.
• Back the player off. Politely ask them to stop playing blackjack, and offer other games.
• Refuse service and ask them to leave — where the law allows it, as in Nevada and Indiana. When Uston was asked to leave in Las Vegas, security read him Nevada's trespass statute.

Which is also the logic of camouflage: its purpose is commercial, not legal. A counter who is spotted stops being profitable not because they broke the law, but because the house simply changes the conditions of the game against them.