A contract, the performance of which is forbidden by rules of law, or the performance of which the law will not enforce, is ordinarily an illegal or a void contract because of the nature of its subject-matter.1 There are, however, cases in which contracts have been held to be unenforceable on the theory that the covenant was one which was legally impossible.2 The leading case on this subject is the case by which an agent agreed to cause the discharge of a debt which was due to his principal.8 Possibly the agent was seeking a private advantage for himself, since the courts referred to the contract as "illegal." If this were the case, the theory of legal impossibility would be superfluous.4 If he was not seeking a personal advantage, but was assuming to act as agent, he was exceeding his authority. Whatever legal consequences might follow, it is not ordinarily regarded as a case of impossibility. It has been held that a contract by which one party covenants that the land of another will sell for a certain price at a certain time, is legally impossible.5 Recent authorities, however, do not regard a contract of this sort as legally impossible.6 A contract by a town to pay for a system of waterworks, which involves the use of wells which the town has not been authorized by law to use, has been held to be invalid as legally impossible.7 A contract which involves the sale of mining land by a locator, in violation of the mining laws of the United States,8 or a contract by which one corporation agrees to discharge its debts by issuing stock of another corporation which is to be formed in the future,9 or a contract by which a parent agrees to transfer the custody of an adult child,10 all have been regarded as contracts to perform legal impossibilities.

8 See ch. LXXXVII.

1 See Sec. 660 et seq.

2 Harvey v. Gibbons, 2 Lev. 161; Providence Albertype Co. v. Kent & Stanley Co., 19 R. I. 561, 35 Ail. 152;

Specht v. Collins, 81 Tex. 213, 16 S. W. 934; Stevens v. Coon, 1 Pinn. (Wis.) 356.

3 Harvey v. Gibbons, 2 Lev. 161.

4 See Sec. 879.

Outside of cases in which no consideration exists, or the subject-matter is such as to render the contract void or illegal, the tendency of modern authorities seems to be strongly against the recognition of the doctrine of legal impossibility.11 A contract by which A agrees to sell B's property at a certain price,12 is regarded as legally possible. A contract by which A agrees to obtain the release of a mortgage which is due to B, and which has been given to secure a debt which is past due, is said to be legally possible, since B can be compelled to accept payment.13

5 Stevens v. Coon, 1 Pinn. (Wis ) 356.

6 Hampe v. Sage, 87 Kan. 536, 125 Pac. 53; Hurless v. Wiley, 91 Kan. 347, L. R. A. 1915C, 177, 137 Pac. 9S1.

7 Smith v. Stoughton, 185 Mass. 329, 70 N. E. 195.

8 Miller v. Thompson, 40 Nev. 35, 160 Pac. 775.

9 Providence Albertype Co. v. Kent & Stanley Co., 19 R. I. 561, 35 Atl. 152.

lO Dittrich v. Gobey, 119 Cal. 599, 51 Pac, 962.

11 England. Hibblewhite v. M'Mor-ine, 5 M. & W. 462.

Alabama. Baker v. Lehman, 1S6 Ala. 493, 65 So. 321.

California. Brimmer v. Salisbury, 167 Cal. 522, 140 Pac. 30.

Kansas. Hampe v. Sage, 87 Kan. 636, 125 Pac. 53; Hurless v. Wiley, 91 Kan. 347, L. R. A. 1915C, 177, 137 Pac. 981.

Michigan. Tyng v. Converse, 180

Mich. 195, 146 X. W. 629.

Oregon. Page v. Ford, 65 Or. 450, 45 L. R. A. (N.S.) 247, 131 Pac. 1013.

A contract by which A agrees to sell property to B. which A does not own at the time of making the contract is legally possible.

England. Hibblewhite v. M'Morine, 5 M. & W. 462.

Alabama. Baker v. Lehman, 186 Ala. 493, 65 So. 321.

California. Brimmer v. Salisbury, 167 Cal. 522, 140 Pac. 30.

Michigan. Tyng v. Converse, 180 Mich. 195, 146 N.W. 629.

Oregon. Page v. Ford, 65 Or. 450, 45 L. R. A. (N.S.) 247, 131 Pac. 1013.

12 Hampe v. Sage, 87 Kan. 536, 125 Pac. 53; Hurless v. Wiley, 91 Kan. 347, L. R. A. 1915C, 177, 137 Pac. 981.

13 Waterman v. Dutton, 6 Wis. 265. (B could not, however, be compelled to accept payment from any one except his debtor or the agent of the debtor.)

As in the case of subsequent impossibility,14 a contract to perform one of two covenants in the alternative, is not regarded as impossible, although performance of one of the covenants is originally impossible, since performance of the alternative covenant is legally possible.15 Even if a covenant by which A agrees that B's land shall sell for a certain price is legally impossible, a covenant by which a vendor agrees that the land which he sells to the vendee shall sell at a certain profit within a certain time, or that in default thereof, the vendor will repurchase such land, and pay the purchase price to the vendee, is enforceable, since the last covenant is legally possible.16