This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
The name "unilateral" has been suggested for contracts executed on one side and executory on the other, or at least for such contracts of this class as are created by performing the act required for acceptance of the offer.1 Contracts of this class are distinguishable from others in the fact that in the other simple contracts the acceptance furnishes the consideration, leaving the performance executory on both sides; while in contracts of this class the acceptance furnishes not only the consideration, but also the performance on one side.
A distinctive name for a contract of this sort is undoubtedly to be desired; and the term "unilateral" is satisfactory enough as far as derivation is concerned. The objection to it is that it is already used too much, with too many meanings. It is used in equity to denote contracts which can not be enforced specifically against one of the parties; and, according to some authorities, will not for this reason be enforced specifically against the other. It is thus employed of the void contract of a married woman, which she is attempting to enforce;2 or of a contract within the Statute of Frauds which has not been signed by the party who seeks to enforce it.3 It is said, accordingly, that such contract ceases to be unilateral when the person who has not signed, files a bill for specific performance,4 or takes possession of the land, so that specific performance can be enforced against him on the theory of part performance.5
5 Louisville, New Albany & Chicago Ry. v. Reynolds, 118 Ind. 170, 20 N. E. 711; Miller v. Sharp, - Ind. - , 100 N. E. 108; John King Co. v. Louisville & Nashville Ry. Co., 131 Ky. 46, 114 8. W. 306; rehearing denied in 116 S. W. 1201.
1 Langdell, Contracts, Sec. 183 et seq. See Sec. 106 and 152.
2 Richards v. Green, 23 N. J. Eq. 638.
3 Chesterman v. Mann, 9 Hare 206; Van Doren v. Robinson, 16 N. J. Eq. 256; Stengel v. Sergeant, 74 N. J. Eq.
20, 68 Atl. 1106; Krah v. Wassmer, 75 N. J. Eq. 109, 71 Atl. 404; Reid v. Savage, 59 Or. 301, 117 Pac. 306.
In most jurisdictions such contract can be enforced against the party who eigned the contract note or memorandum. See Sec. 1325.
4 Richards v. Green, 23 N. J. Eq. 636; Krah v. Wassmer, 75 N. J. Eq. 109, 71 Atl. 404.
5 Cramer v. Mooney, 59 N. J. Eq. 164, 44 Atl. 625.
6 Lafitto v. Shawcross, 12 Fed. 519.
The term "unilateral" is also used to denote a promise which has not been so accepted by the promisee as to impose any liability upon him; or which does not by its terms purport to impose any liability upon him,7 as of an unaccepted offer.8 An offer for value is spoken of as a unilateral contract before acceptance,9 even though the value for the option may itself be a promise and the entire transaction may be executory.10 A gratuitous promise is often spoken of as unilateral,11 such as a promise for which the only consideration is a counter-promise which is so indefinite as to be unenforceable.12 The term often imports an unenforceable promise, as distinguished from one that is enforceable.13 A contract is said to be "unilateral and unenforceable;"14 or "unilateral and void for want of mutuality."15 Conversely when it is said that a contract is not unilateral it is meant that it is valid.16 A contract or option is sometimes said not to be unilateral if it is supported by a consideration An option for the purchase of land which is contained in a lease of such land is said not to be "unilateral and without consideration." 17 As a result of these uses of the term, it is said that a contract can not be unilateral if it is really a contract.18 Even if the courts are speaking of a unilateral contract, they are likely to use the term "unilateral" of the offer rather than of the contract,19 and to say that when it becomes a contract it ceases to be unilateral. A unilateral contract is said to be a mere offer that, if subsequently accepted and acted upon by the other party to it, would ripen into a binding enforceable obligation.20 It is said to lack mutuality at its inception and to be binding only on performance by the promisee.21 A provision in a conveyance of timber, for an extension of timber at the election of the grantor,22 or a covenant to sell land at a certain price which does not impose upon the vendee the duty of paying such price and therefore can be accepted only by tendering such payment23 have each been said to be unilateral. An option for value is said to be unilateral, whether the consideration consists of an act, as is usually the case, or of a promise.24 In some cases the term "unilateral" is used in the sense originally suggested; that is, as meaning a valid contract in which the offer calls for acceptance by doing an act, and accordingly, the acceptance is not only acceptance but also consideration and performance as well.25
7 United States. Johnson v. Staen-glen, 85 Fed. 603; Tweedie Trading Co. v. Parlin & Orendorff Co., 204 Fed. 50.
Colorado. Hardwick v. McClurg, 16 Colo. App. 354, 65 Pac. 405.
Georgia. Harrison & Garrett v. Wilson Lumber Co., 119 Ga. 6; 45 S. E. 730; Atlanta Oil & Fertilizer Co. v. Phosphate Mining Co., 144 Ga. 75, 86 S. E. 216.
Illinois. Plumb v. Campbell, 129 111. 101; 18 N. E. 790; Joliet Bottling Co. v. Joliet Citizens' Brewing Co., 254 111. 215, 98 N. E. 263.
Kansas. It is said to be "unilateral and subject to revocation"; Braniff v. Baier, 101 Kan. 117, L. R. A. 1917E, 1036, 165 Pac. 816.
Kentucky. Turner v. Frazier, 157 Ky. 388, 163 S. W. 245; Goff v. Saxon, 174 Ky. 330, 192 S. W. 24.
New York. Levin v. Dietz, 194 N. Y. 376, 87 N. E. 454.