Wager, in law, a contract by which two parties agree that a certain thing shall be done by one for the benefit of the other, on the happening or not happening of a contingent event. Wagers were certainly valid contracts at common law, but from early ages many exceptions were made. They were void if immoral, or opposed to public policy, or indecent, or tending to restrain or prevent marriage. In the United States, the objection has been extended to any wager about the age, height, weight, wealth, situation, or circumstances of any person, of any age or either sex. So, too, all wagers are void, and perhaps punishable, if such as to interfere with the free and honest exercise of the elective franchise. By the statute 8 and 9 Victoria, ch. 100, sec. 18, all wagers are null and void. Many of the states have similar statutes, and the general tendency of adjudication has been in the direction of making all wagers nullities. It may be said to be the general rule that money deposited on a wager may be recalled before the event is decided, and in many, perhaps in a majority of the states, at any time before it has been paid over.

In some states by statute anything won on a wager and actually paid over may be recovered by the loser, and wagers, particularly on elections, are made punishable as offences. In Missouri, New York, and Wisconsin, by constitutional provisions, and in some other states by statutes, wagers on an election disqualify the parties making them from voting at that election. It may be doubted now whether an action by a winner of a mere wager or bet against a loser would be sustained in any court.