The rules of the game are referred to as the 'Laws' as promulgated by various bridge organizations. [edit]Laws of duplicate bridge Main article: Laws of Duplicate Bridge The official rules of duplicate bridge are promulgated by the World Bridge Federation (WBF) as the "International Code of Laws of Duplicate Bridge, 2007".[14] The Laws Committee of the WBF, composed of world experts, updates the Laws every 10 years; it also issues a Laws Commentary advising on interpretations it has rendered. In addition to the basic rules of play there are many additional rules covering playing conditions and the rectification of irregularities which are primarily for use by tournament directors who act as referees and have overall control of procedures during competitions. In addition, some details of procedure are left to the discretion of the zonal bridge organisation for tournaments under their aegis and some (for example, the choice of movement) to the sponsoring organisation (e.g. the club). The zonal organisations of the WBF also publish editions of the Laws. For example, the American Contract Bridge League publishes "Laws of Duplicate Bridge, 2008",[15] "Laws of Contract Bridge, 2003"[16] and additional supporting documentation including: Director Decisions, Tech Files and Casebook (appeals from national bridge championships).[17] [edit]Rules of rubber bridge There are no universally accepted rules for rubber bridge promulgated by bridge governing bodies; instead local rules such as The Laws of Contract Bridge as published by the American Contract Bridge League constitute the rules for those wishing to abide by a published standard.[18] The majority of rules mirror those of duplicate bridge in the bidding and play and differ primarily in procedures for dealing and scoring. [edit]Law of online play In 2001, the World Bridge Federation promulgated a set of Laws for online play. The American Contract Bridge League (ACBL) is the largest contract bridge organization in North America.[1] It promotes the game of bridge in the United States, Mexico, Bermuda, and Canada, and is a member of the World Bridge Federation.[2] ACBL games and tournaments use the duplicate bridge method of scoring, where the luck of getting a series of good hands doesn't necessarily mean a better score. The ACBL, a not-for-profit organization, was founded in 1937[1] in New York City and later moved its company headquarters to Greenwich, Connecticut. ACBL moved from Greenwich, Connecticut to Memphis, Tennessee in 1971[3] and to Horn Lake, Mississippi in 2010.[4] It has a full-time staff of 75 employees in the headquarters, plus about 170 tournament directors throughout the country.[1] As of 2009 it had more than 160,000 members.[1] Members receive the Bridge Bulletin magazine, but for many of them, the most significant role of the ACBL is its sanctioning of club games and tournaments to award masterpoints. If an event has the ACBL sanction, then the highest-finishing players are awarded specified numbers of masterpoints, which can be recorded with the ACBL. Most players value the increase in their masterpoint total as a measure of their success at the game. Unlike the Elo rating system developed for chess, the masterpoint system is strictly one of accumulation. A player's masterpoint total can never decline. Besides the Bridge Bulletin, other ACBL publications include the Laws of Duplicate Bridge (its name was Laws of Duplicate Contract Bridge until 2008), the ACBL Bridge Series of lessons for beginners, and free instructional software. The ACBL certifies bridge teachers and club directors.