The obligation of the principal debtor, in the absence of an express undertaking, to indemnify his surety, had its origin in equity.2 Lord Mansfield had no hesitation, however, in enforcing it at law in an action for money paid to the principal's use:

1 Brown v. Hodgson, 1811, 4 Taunt. 189, (plaintiff, a carrier, who had misdelivered goods to defendant instead of to P. and who paid P. the value of the goods, allowed to recover from defendant); Brittain v. Lloyd, 1845, 14 Mees. & Wels. 762, (auctioneer who had paid duty allowed to recover from his employer); Lewis v. Campbell, 1849, 8 C. B. 541.

2 Layer v. Nelson, 1687, 1 Vera. 456.

Decker v. Pope, 1757, 1 Selw. N. P. 76 n.: "Lord Mansfield directed the jury to find for the plaintiff; observing, that where a debtor desires another person to be bound with him or for him, and the surety is afterwards obliged to pay the debt, this is a sufficient consideration to raise a promise in law, and to charge the principal in an action for money paid to his use."

Lord Mansfield's statement that the obligation of the principal arises upon payment by the surety indicates clearly a quasi contractual character. In a number of cases it appears to have been so regarded.1 That it has come to be treated generally as a genuine implied contract, however, is evidenced by the abundant authority which holds that the obligation arises when the surety becomes bound, rather than when the surety pays.2

1 Toussaint v. Martinnant, 1787, 2 Term R. 100; Townsend v. Sullivan, 1906, 3 Cal. App. 115; 84 Pac. 435; Vermeule v. York Cliffs Improvement Co., 1909, 105 Me. 350.; 74 Atl. 800; 134 Am. St. Rep. 553; Norton v. Coons, 1851, 6 N. Y. 33; Tobias v. Rogers, 1855, 13 N. Y. 59; Johnson v. Harvey, 1881, 84 N. Y. 363; 38 Am. Rep. 515; Oldham v. Broom, 1874, 28 Oh. St. 41; Aldrich p. Al-drich, 1883, 56 Vt. 324; 48 Am. Rep. 791.

"Again, it is an equitable principle of very general application that where one person is in the situation of a mere surety for another, whether he became so by actual contract or by operation of law, if he is compelled to pay the debt which the other in equity and justice ought to have paid, he is entitled to relief against the other, who was in fact the principal debtor. And when courts of law, a long time since, fell in love with a part of the jurisdiction of the court of chancery and substituted the equitable remedy of an action of assumpsit upon the common money counts, for the more dilatory and expensive proceedings by a bill in equity in certain cases, they permitted the person thus standing in the situation of surety, who had been compelled to pay money for the principal debtor, to recover it back again from the person who ought to have paid it, in this equitable action of assumpsit as for money paid, laid out, and expended for his use and benefit." - Walworth, Ch., in Hunt v. Amidon, 1842, 4 Hill (N. Y.) 345, 348; 40 Am. Dec. 283.

2 In re Stout, 1900, 109 Fed. 794, (D. C. Mo.); Keel v. Larkin, 1882, 72 Ala. 493; Choteau v. Jones, 1849, 11 111. 300; 50 Am. Dec. 460; Sargent v. Salmond, 1847, 27 Me. 539; Appleton v. Bascom, 1841, 3 Metc. (Mass.) 169; Labbe v. Bernard, 1907, 196 Mass. 551; 82 N. E. 688; 14 L. R. A. (N. S.) 457 (semble); Loughridge & Bogan v. Bowland, 1876, 52 Miss. 546; Carlisle v. Rich, 1835, 8 N. H. 44,