If the obligation which it is sought to enforce is one which is created by the express agreement of the promisor, it is laid down as a general rule, subject to exceptions which are considered hereafter,1 that subsequent impossibility does not excuse performance.2 Since there are certain wellrecognized exceptions to this rule,3 it is clear that the rule itself is not intended as a complete or agreed statement of the law. In most cases in which it is necessary to lay down a general rule and then to qualify the rule by a number of exceptions, either the original rule is stated inadequately, on the one hand, or else the courts have decided the cases as they arise without any regard to general theory. The lack of a general theory is apparent as soon as an attempt is made to state the classes of the exceptions to the general rule; and it is even more apparent when an attempt is made to formulate a general principle which underlies the specific classes of exceptions and which will solve new cases as they arise. Attempts have been made to state a general principle which will explain all the recognized exceptions.

20 Pittsburg, C. C. & St. L. R. Co. v. Chicago, 242 Ill. 178, 44 L. R. A. (N.S.) 358, 89 N. E. 1022; Missouri Pacific Ry. v. Nevill, 60 Ark. 375, 46 Am. St. Rep. 208, 28 L. R. A. 80, 30 S. W. 425.

21 Merchants' Despatch Co. v. Smith, 76 Ill. 542.

22 Herter v. Mullin, 159 N. Y. 28, 70 Am. St. Rep. 517, 44 L. R. A. 703, 53 N. E. 700; Grice v. Todd, 120 Va. 481, L. R. A. 1917D, 512, 91 S. E. 609.

Contra, Mason v. Wierengo, 113 Mich. 151, 67 Am. St. Rep. 461, 71 N. W. 489.

23 Herter v. Mullen, 159 X. Y. 28, 70 Am. St. Rep. 517, 44 L. R. A. 703, 53 N. E. 700.

24 Grice v. Todd, 120 Va. 481, L. R. A. 1917D, 512, 91 S. E. 609.

25 Haynes v. Aldrich, 133 N. Y. 287, 28 Am. St. Rep. 636, 31 N. E. 94.

1 See Sec. 2676 et seq.

2 England. Prince v Haworth [1905] 2 K. B. 768.

United States. Dermott v. Jones, 69 U. S. (2 Wall.) 1, 17 L. ed. 702; The Harriman, 76 U. S. (9 Wall) 161, 19 L. ed. 629; Jones v. United States, 96 U. S. 24, 24 L. ed. 644; Chicago, M. & St. P. Ry. v. Hoyt, 149 U. S. 1, 37 L. ed. 625; Jacksonville, M. P. R. & Nav. Co. v. Hooper, 160 U. S. 514, 40 L. ed. 515; Northern P. R. Co. v. American Trading Co., 195 U. S. 439, 49 L. ed. 269; Barry v. United States, 229 U. S. 47, 57 L. ed. 1060; Columbus Railway, Power & Light Co. v. Columbus, 249 U. S. 399, - L. ed. - [affirming, 253 Fed. 4991; Central Trust Co. v. Wabash, St. L. & P. R. Co., 31 Fed. 440; Robson v. Mississippi River Logging Co., 61 Fed. 893;

Link Belt Engineering Co. v. United States, 142 Fed. 243; Ferguson v. Omaha & S. W. R. Co., 227 Fed. 513; Berg v. Erickson, 234 Fed. 817, L. R. A. 1917A, 648.

Alabama. McGehee v. Hill, 4 Port. (Ala.) 170, 29 Am. Dec 277; Meriwether v. Lowndes County, 89 Ala. 362, 7 So. 198.

California. Law v. San Francisco Gas & Electric Co., 168 Cal. 112, 142 Pac. 52.

Connecticut School Dist v. Dauchy, 25 Conn. 530, 68 Am. Dec. 371.

Illinois. Summers v. Hibbard, 153 Ill. 102, 46 Am. St. Rep. 872, 38 N. E. 899.

Indiana. Prather v. Latshaw, -Ind. -, 122 N. E. 721.

Iowa. Mahaska County State Bank v. Brown, 159 Ia. 577, 141 N. W. 459.

Kansas. Cox v. Chase, 95 Kan. 531, L. R. A. 1915E, 590, 148 Pac. 766; Carter v. Wilson, 102 Kan. 200, 169 Pac. 1139.

Kentucky. Louisville & N. R. Co. v. Crowe, 156 Ky. 27, 49 L. R. A. (N.S.) 848, 160 S. W. 759.

Maryland. Ess-Arr Knitting Mills v. Fischer, 132 Md. 1, 103 Atl. 91.

Massachusetts. Adams v. Nichols, 36 Mass. (19 Pick.) 275, 31 Am. Dec. 137; Rowe v. Peabody, 207 Mass. 226, 93 N. E. 604.

Minnesota. Cowley v. Davidson, 13 Minn, 92; Stees v. Leonard, 20 Minn. 494; Anderson v. May, 50 Minn. 280, 36 Am. St. Rep. 642, 17 L. R. A. 555, 62 N. W. 530; Belle Plaine First National Bank v. McConnell, 103 Minn. 340, 123 Am. St. Rep. 336, 14 L. R. A. (N.S.) 616, 114 N. W. 1129 (obiter); Halloran v. Schmidt Brewing Co., 137 Minn. 141, L. R. A. 1917E, 777, 162 N. W. 1082.

Mississippi. Hood v. Moffett, 109 Miss. 757, L. R. A. 1916B, 622, 69 So. 664.

New York. Beach v. Crain, 2 N. Y. 86, 49 Am. Dec. 369; Tompkins v. Dudley, 25 N. Y. 272, 82 Am. Dec. 349; Dexter v. Norton, 47 N. Y. 62, 7 Am. Rep. 415; Stewart v. Stone, 127 N. Y. 500, 14 L. R. A. 215, 28 N. E. 595.

North Dakota. Grady v. Schweinler,

16 N. D. 452, 125 Am. St. Rep. 674, 14 L. R. A. (N.S.) 1089, 113 N. W. 1031; Gile v. Interstate Motor Car Co., 27 N. D. 108, L. R. A. 1915B, 109, 145 N. W. 732.

Pennsylvania. Hoy v. Holt, 91 Pa. St. 88, 36 Am. Rep. 659. Rhode Island. Parker v. Macomber,

17 R. I. 674, 16 L. R. A. 858, 24 Atl. 464. Virginia. Virginia Iron, Coal & Coke

Co. v. Graham, - Va. -, 98 S. E. 659.

West Virginia. Vale v. Suiter, 58 W. Va. 353, 52 S. E. 313.

3 See Sec. 2676 et seq.

It has been said that any subsequent act or event which prevents performance must be regarded as operative impossibility which will discharge the contract, as it appears that the parties intended such act or event as an implied condition subsequent upon the happening of which the contract should be discharged.4 As in other cases in which the doctrine of implied conditions is invoked,5 the courts are attempting to justify the result, which they have reached on other grounds, by the use of a fiction which is unnecessary and which gives no help to the solution of cases in advance. Until we know whether the court regards the subsequent act or event as amounting to operative impossibility which discharges the contract, it is impossible to know whether the court regards such act or event as an implied condition subsequent.

Another attempt to state the general theory which underlies the exceptional cases in which operative impossibility exists, puts the principle in the following form: If the subsequent act or event which prevents performance is one which is not fairly within the meaning of the contract, and which the parties can not be assumed to have contemplated when they entered into the contract, such act or event amounts to operative impossibility and discharges performance.6