Marked Cards


There are hundreds of ways to mark cards, and new systems seem to be surfacing every year—mostly high-tech systems. Developing a system that detects all forms of marked cards is no easy challenge, but it’s a solvable problem, a fact that ST proved after embarking on the most comprehensive marked card study ever conducted!

There are plans to publish the complete study later in 2017, but for now, due to confidentiality considerations, only a few of the study’s sources are listed below.

  • Dozens of casino executives and game-protection experts were interviewed to get a sense of which marked-card scams and methods were most common and most dangerous.

  • ST was allowed access to the largest collection of marked cards known to exist, consisting of approximately 3,000 decks with over 500 different marking systems. The collection also included the corresponding ‘keys’ (instructions for reading a marking system) and customer records from some of the most prominent crooked gambling supply houses (still operating into the 1970s, although they eventually closed down due to new federal laws prohibiting the interstate transportation of gambling equipment).

  • ST was also allowed access to several of the largest private gambling libraries. Sources starting from the 1840s to the present, pertaining to cheating and especially marked cards, including books, magazines, newspapers, pamphlets, and catalogs, were reviewed.

  • Dozens of online crooked-gambling-supply companies from all over the world, currently selling high-tech cheating equipment and marked cards, were also reviewed.

As a result of this extensive research, hundreds of marking systems were revealed. Every system, substance, formula, and method uncovered was then listed, categorized, and evaluated from an algorithmic perspective. This is the key. The only way to detect all forms of marked cards—past, present, and future—is with a comprehensive, analytical strategy and synergy of sophisticated algorithms. To ensure the integrity of every assessment, ST works on the premise that an anomaly independent of several supporting factors does not indicate a marked card. Repeatable tests and multiple layers of confirmation are required before ST reaches its first threshold: an indicator that one or more anomalies are unlikely to have occurred by chance. After the system reaches its second threshold, only then does it provide proof of foul play. The ST system is wholly based on scientific precision and redundancy, and has been specifically developed with the goal of eliminating false positives.

Finally, when the data generated by individual shufflers is shared with all other shufflers, comparative thresholds are created that allow operators to make game-protection decisions on individual games that are supported by information derived from all games.