Contract bridge grand slam exists. The modern game of contract bridge was the result of innovations to the scoring of auction bridge by Harold Stirling Vanderbilt and others. The most significant change was that only the tricks contracted for were scored below the line toward game or a slam bonus, a change that resulted in bidding becoming much more challenging and interesting. Also new was the concept of "vulnerability", making sacrifices to protect the lead in a rubber more expensive. The various scores were adjusted to produce a more balanced and interesting game. Vanderbilt set out his rules in 1925, and within
Boston (card game) in a contract to win at least eight tricks between them. The higher bid of Independence offers to win at least eight tricks playing solo. In either way, there is an extra bonus for winning all thirteen tricks formerly called "la vole", but now "le chelem", from English "Slam". All bids are solo, the lowest being to take four tricks in any suit. Each may be over-called by bidding higher number of tricks, or the same number in a better suit. For this purpose a better suit is that of Preference, previously determined by turning the last card of the