A vital distinction in contracts exists between (1) those where each party promises some performance and, (2) those where only one party promises performance, the consideration from the promisee being actually given. The former are called bilateral, the latter unilateral. The recognition of unilateral contracts by the law antedated the recognition of bilateral contracts by about a century.41 Both bilateral and unilateral contracts may be made as contracts under seal, or as simple contracts. The distinction between these two kinds of contracts was fully recognized three hundred years ago, but lack of appropriate names caused the distinction and its consequences to be frequently overlooked in the later history of the law.41 Even to-day it is frequently said in the opinions of net, C. B., delivering the opinion of the judges to the House of Lords, Rann v. Hughes, 7 T. R. 350, note (a). See also Hillas v. Fuller, 143 N. Y. S. 15; Kime v. Tobyhanna Creek Ice Co., 240 Pa. 61, 87 Atl. 278. It in an illustration of the unfortunate ambiguity too common in the terminology of our law that "parol" is also used to distinguish written from oral contracts, e. g., under the so-called "parol evidence" rule.

40See infra, {99.


42The earliest use of the words bilateral or unilateral in our law, in the sense in which they are here used, seems to have been by Judge Dillon, in Barrett v. Dean, 21 ls. 423. Though Judge Story in D'Wolf v. Rahaud, 1 Pet 476, 500, 7 L. Ed. 227, speaks of contracts where one consideration is furnished by A in exchange for two several promises by B & C as "if one might use the phrase, a trilateral contract." Trilateral is used in the same sense in Aultman v. Fletcher, 110 Ala. 452, 458, 18 So. 215. The terms bilateral and unilateral were popular-used by Professor Langdell, and are now in common use in the reports. See, e. g., Stevenson v. McLean, 5 Q. B. D. 346, 351; Davis v. Wells, 104 U. S. 159, 166, 26 L. Ed. 686; Harmon v. Adams, 120 V. S. 363,365,30 L. Ed. 683; Howe v. Howe & Owen Co., 154 Fed. 820, 83 C. C. A. 536; Howard v. East Tenn. etc. R. Co., 91 Ala. 268, 269,8 So. 868; Los Angeles Traction Co. v. Wilshire, 135 Cal. 654, 658, 67 Pac. 1086; Plumb v. Campbell, 129 111. 101, 18 N. E. 790; Nowlin v. Pyne, 40 la. 166; Coleman v. Applegarth, 68 Md. 21, 25, 27, 11 Atl. 284, 6 Am. St. Rep. 417; First Nat. Bank v. Watkins, 154 Mass. 385, 387, 28 N. E. 275; Thomas v. Barnes, 156 Mass. 581, 31 N. E. 6S3; Averill courts that both parties must be bound, or that there must be mutuality of obligation in a contract.42 Such statements are true only of bilateral contracts. An offer of reward, an offer of a price for goods, or for services, becomes a contract when what is requested is given or done, though no obligation to give or to do anything ever exists.43

The term unilateral contract is not infrequently used with a slightly different meaning from that here given; namely, to designate a promise for which no consideration was requested, or for which no sufficient consideration was given.44 It will be noticed that in this use of the word unilateral as well as in the use suggested earlier in this section, the word indicates a promise made by one party to a bargain. If no sufficient consideration was requested for that promise or, if, though requested, the consideration was not given, the transaction is undoubtedly unilateral, but it is not a unilateral contract. A contract may give rise merely to an imperfectly enforceable obligation but one which creates no obligation is a contradiction in terms.45 Therefore the term unilateral contract should be reserved for cases where a binding obligation has been v. Boston, 193 Mass. 488, 494,80 N. E, 583; McMillan v. Ames, 33 Minn. 267, 22 N. W. 612; Stensguard v. Smith, 43 Minn. 11, 15.44N. W.669;Underwood Typewriter Co. v. Century Realty Co., 220 Mo. 522,119 S. W. 400, 25 L. R. A. (N. S.) 1173; Feudtner v. Roes, 74 N. J. Eq. 214, 69 Atl. 190; Stengel v. Sergeant, 74 N. 3. Eq. 20, 68 Atl. 1106; Post v. Frank, 132 N. Y. Supp. 807, 75 N. Y. Misc. 130; Wiley v. Broaddua Ac Lumber Co., 156 N. C. 210, 72 S. E. 305; Winders v. Kenan, 161 N. C. 628, 77 S. E. 687; Barrow 8. 8. Co. v. Mexican Cent. Ry. Co., 134 N. Y. 15, 24, 31 N. E. 261, 17 L. R. A. 859; Lemlet v. Bord, 80 Oreg. 224, 156 Pac. 427.

42aSee infra, Sec.140.

43See, e. g.. Peoples v. Citizens Ins. Co., 11 Ga. App. 177, 74 S. E. 1034; Train p. Gold, 5 Pick. 380, 384; Taylor v. Barbour, 90 Miss. 888, 44 So. 988, 122 Am. St. Rep. 328; Miller v. Mc-Kenxie, 95 N. Y. 575, 47 Am. Rep. 85;

Grossman v. Schenker, 206 N. Y. 466, 100 N. E. 39.

44 Great Northern Railway Co. p. Witham, L. R. 9 C. P. 16; Johnson v. Staenglen, 85 Fed. 603, 606,29 C. C. A. 369; Fuleowider v. Rowan, 136 Ala. 287, 306; Hardwick v. McCIurg, 16 Col. App. 354, 65 Pac. 405, 408; Harrison v. Wilson Lumber Co., 119 Ga. 6, 45 S. E. 730,731; Terry v. International Cotton Co., 136 Ga. 187, 70 S. E. 1100; Buick Motor Co. v. Thompson, 138 Ga. 282, 75 S. E. 354; Luke v. Livingston, 9 Ga. App. 116, 70 8. E. 21; Joliet Bottling Co. v. Joliet Brewing Co., 254 111. 215, 98 N. E. 263, 265; Levin v. Dietz, 194 N. Y. 376,87 N. E. 454,20 L. R. A. (N. S.) 251; Mutual Film Corp. v. Morris (Tex. Civ. App.), 184 S. W. 1060; Abba v. Smyth, 21 Utah, 109, 117, 59 Pac. 756.

45 In High Wheel Auto Parts Co. v. Journal Co., 50 Ind. App. 396,98 N. E. 442, 443, the Court said of the phrase crested, but only one party to the obligation has made a promise. Where there is no binding obligation, the transaction may be a unilateral promise or a unilateral offer, but it certainly cannot properly be called a unilateral contract.46 Contracts may be partly bilateral and partly unilateral; that is, the consideration on one or on both sides may consist partly of acts and partly of promises

Obligations have also been divided into unifactoral and bifactoral obligations: the former created by one party alone, the latter by the act of two.46a Simple contracts are necessarily bifactoral, but in the early common law at least, and in some jurisdictions still, assent on the part of the promisee is not essential to the validity of a contract under seal. A debt or a quasi-contractual obligation also may arise without any assent on the part of the debtor, and, occasionally, without any volition on the part of the creditor.47

Sec.14. Executed And Executory Contracts

If a transaction is fully executed on both Bides, it is not properly described as a contract. The term "executed contract" has, however, been sometimes used to describe executed consensual agreements, like sales completely carried out on both sides. The same term has also been used to describe unilateral contracts which are executed on one side only, as sales where the price has not yet been paid. Since the phrase if understood in the former meaning contains an improper use of the word contract, and in any event is ambiguous, its use is better avoided. The same criticism, so far as ambiguity is concerned, applies to the phrase "executory contracts." All unilateral contract as thus used, that it is a "legal solecism."

46A somewhat similar use of the word unilateral is occasionally found in cases where specific performance of a contract is sought and objection made that the contract lacks the so-called mutuality necessary for the allowance of the remedy of specfic performance. A bargain open to such an objection is sometimes said to be unilateral. See Pomeroy's Equity Jurisprudence (3d ed.) Sec. 1405, n. 3; Stengel v. Sergeant, 74 N. J. Eq. 20, 68 Atl. 1106.

46a Harriman, Contracts (2d ed.), Sec.617.

47 For instance, if A devises land to B subject to a charge that B shall pay C one thousand dollars, if B accepts the devise, C may bring debt against him for the money and no previous acceptance or assent by C seems necessary.

contracts to a greater or less extent are executory. When they cease to be so, they cease to be contracts.

Sec. 15. Void And Voidable Contracts

An agreement which produces no legal obligation is often called a void contract. Though the phrase is often convenient, it is a contradiction in terms. If the agreement is void it is not a contract. A voidable contract, however, is common in the law. Infancy, fraud, mistake, duress, some kinds of illegality, all afford ground for rescinding or refusing to perform a contract. Unless rescinded, however, a voidable contract imposes on the parties the same obligations as if it were not voidable. Some distinctions in different kinds of contracts which are called voidable are hereafter noticed.48