Because of its tendency to promote illegal acts a contract to save the promisee harmless from the consequences of an act which is necessarily unlawful is itself invalid.17 Thus a contract to indemnify an officer against the consequences of making such a seizure of property as is necessarily tortious in view of such facts known to the parties is invalid;18 though if the illegality depended upon extrinsic facts unknown to the parties, the contract of indemnity would be valid.19 A contract to indemnify a publisher against the consequences of publishing a libel is similarly invalid.20 But where it was not anticipated that any libel would be contained in a book, though out of abundant caution there was inserted in the contract of publication an undertaking by the author that he would indemnify the publisher against the consequences of any libel which the book might contain, the contract was upheld;21 and for the same reason agreements to indemnify trustees against formal breaches of trust are in practice constantly assumed to be valid, both in England,22 and in the United States.

Contracts insuring against the consequences of negligence, and undertakings by contractors to assume liability for all damages incurred in the prosecution of work are upheld.23 A contract to indemnify against the consequences of an illegal act already committed is also valid,24 unless there was an understanding prior to the commission of the illegal act that subsequently indemnity should be given;25 or unless the illegal act in question was an unprosecuted crime, in which case the agreement would be open to the objection of tending to stifle prosecution.26

17 Bierbauer v. Wirth, 5 Fed. 336; Cooper v. Northern Pac. Ry. Co., 212 Fed. 533; Collier's Adm'r v. Windham, 27 Ala. 291, 62 Am. Dec. 767; James v. Hendree's Adm'r, 34 Ala. 488; Kenna v. Calumet Ac. Co. (111.), 120 N. E. 259; Lebanon Carriage Co. v. Faulkner, 25 Ky. L. Rep. 1037, 76 S. W. 1083; Jose v. Hewett, 50 Me. 248; Babcock v. Terry, 97 Mass. 482. In Boylston Bottling Co. v. O'Neill, 231 Mass. 498, 121 N. E. 411, the defendant guaranteed the collections made by the plaintiff's driver. Recovery on the guaranty was denied because the drivers' duty partly consisted of delivering liquor in a no-license town in violation of law. Cf. Messersmith 9. American Fidelity Co., 187 N. Y. App. D. 35, 175 N. Y. S. 169.

18 Martyn v. Blithman, Yelv. 197; Thompson v. Rock, 4 M. & S. 338;

Samuel 9. Evans, 2 T. R. 569; Mosedel v. Middleton, T. Raymu 222; Knipe v. Hobart, 1 Lutw. 229; Buffendeau 9. Brooks, 28 Cal. 641; Hodsdon v. Wilkins, 7 Me. 113, 20 Am. Dec. 347; Ayer v. Hutchins, 4 Mass. 370, 3 Am. Dec. 232; Love v. Palmer, 7 Johns. 159; Webber v. Blunt, 19 Wend. 188, 32 Am. Dec. 445.

19 See supra, Sec. 1631.

20 Clay v. Yates, 1 H. & N. 73; Col-burn v. Patmore, 1 C. M. & R. 73; Shackell 9. Rosier, 2 Bing. (N. C.) 634; Gale v. Leckie, 2 Stark. 107; Arnold v. Clifford, 2 Sumn. 238; Lea v. Collins, 4 Sneed, 393; Atkins v. Johnson, 43 Vt. 78, 5 Am. Rep. 260.

21 C. F. Jewett Publishing Co. v. Butler, 159 Mass. 517, 34 N. E. 1087, 22 L. R. A. 253, Lathrop, J., dissented.

22 Wald's Pollock, Cont. 3d ed. 377 note (m).