Preemptive bid

Preempt (also spelled "pre-empt") is a bid in contract bridge whose primary objectives are (1) to thwart opponents' ability to bid to their best contract, with some safety, and (2) to fully describe one's hand to one's partner in a single bid. A preemptive bid is usually made by jumping, i.e. skipping one or more bidding levels. Since it deprives the opponents of the bidding space, it is expected that they will either find a wrong contract (too high or in a wrong denomination) of their own, or fail to find any. A preemptive bid often has the aim of a sacrifice, where a partnership bids a contract knowing it cannot be made, but assumes that (even when doubled), the penalty will still be smaller than the value of opponents' bid and made contract.

The tables at right help to illustrate the limits of the scoring advantage to be gained in duplicate bridge by preempting or sacrificing when the opponents may be successful in making a game contract. The level to which one may preempt, bid competitively or ultimately sacrifice is heavily influenced by the vulnerability status of each side and the assumption that the defending side will double the contract. There are four possible scenarios:

In summary, based upon the expectation that the opponents are likely to bid and make game, it is advantageous to preempt, compete or sacrifice for down three when vulnerability is favorable, down two when equal and down one when unfavorable.

A preemptive opening bid is one made on the second or higher level, typically showing a weak hand containing a long, strong suit. Preemptive opening bids on the third or higher level are common for most bidding systems; for example, the hand of ♠ 4 ♥ KQJ9854 ♦ J62 ♣ 95 is a typical 3♥ opener. The bid is made on presumption that, without any additional tricks from the partner, at least six tricks can be taken with hearts as trump, and the potential penalty of 500 points in 3♥ doubled is smaller than the value or opponents' likely game or slam.

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