Grand slam force Grand slam force The Grand Slam Force is a bidding convention in contract bridge that was developed by Ely Culbertson in 1936. It is intended to be used in cases where the combined hands of a partnership are so strong that a slam (winning at least 12 tricks) is a near-certainty and a grand slam (winning all 13 tricks) is a possibility. It allows one partner to gain information on the quality of trumps in the other partner's hand. When this convention is in force, a bid of 5NT (five notrump), when it does not conflict with other conventions used
American Contract Bridge League American Contract Bridge League The American Contract Bridge League (ACBL) is the governing body for contract bridge in the United States, Mexico, Bermuda and Canada and is a member of the World Bridge Federation, the international bridge governing body. It is the largest such organization in North America having the stated mission ""to promote, grow and sustain the game of bridge and serve the bridge-related interests of our Members."" Its major activities are: , it had more than 165,000 members. A not-for-profit organization, the ACBL was founded on December 23, 1937 in New York City and later moved its company