As will appear from the following sections, wagers and gaming contracts are generally illegal. The typical wager is familiar but the essential feature of a wager making it illegal must be understood in order that the various kinds of agreements which come within the inhibition of the law as wagering or gambling agreements may be understood. It is the essence of such an agreement that if its terms are carried out and a promisor is compelled by the happening of the condition of his promise to perform it, on the one hand neither he nor a third person will have received anything of commensurate value, or regarded by the parties as of commensurate value, with the performance which he himself renders, and on the other hand the promisee will have suffered no detriment commensurate or regarded as commensurate with the performance. It is not essential that both parties shall make an aleatory promise. Doubtless such a bilateral chance is essential in what is strictly called a wager or bet; and in a jurisdiction where the illegality of wagering or gaming contracts depends wholly upon statutes, the words of the statute must be considered;1 but no such narrow limits can be fixed for the prohibitions of public policy in a jurisdiction which holds wagering contracts invalid, apart from statute. It is the characteristic of a lottery that one party pays a definite sum in return for a promise of receiving a greater sum or greater value in a certain contingency. Yet "every lottery has the characteristics of a wager or bet although every wager is not a lottery." 2 Lotteries though almost universally prohibited by state constitutions and statutes, seem open, apart from legislation, to the same objection as any gambling contract in jurisdictions where the common law denies validity to wagers. Therefore a contract by which a purchaser pays a fixed sum in return for a promise to convey such a one of a number of lots, as may be determined by the drawing of lots, is invalid.3 A wagering policy of insurance also is invalid,4 though but one of the parties makes an aleatory promise.
1 So in England it has been said "If either of the parties may win but cannot lose or may lose, but cannot win, it is not a wagering contract." Hawkins, J., in Garlill v. Carbolic Smoke Ball Co.,  2 Q. B. 484, 401. See also Thacker v. Hardy, 4 Q. B. D. 685, 605; Forget v. Ostigny,  A. C. 318, 326; Quarles v. State, 5 Humph. 561. Cf. the definition of "gambling " in Lang v. Merwin, 99 Me. 486, 59 Atl. 1021, 105 Am. St. 293; and see
Richards v. Starck  1 K. B. 296, 302, where Channel!, J., said of the English definition that "a state of things has arisen which makes one doubt whether the definition can be treated as exhaustive." In that case although the plaintiff was to receive back, in any event, a deposit which he made, the loss of interest which he suffered if no profit was made was held to bring the transaction within the English Statute.