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 next step in the development of assumpsit was to differentiate it from the other forms of trespass on the case. This was a slow process. At one time the courts seemed inclined to take the position that assumpsit was not to be classed with contracts at all.1 For a long time the courts which enforce executory contracts and which recognize the action of assumpsit, call it an action on the case. It becomes more and more frequent, however, to find the heading "assumpsit" added wherever the action is based upon an executory contract; but up to a very late stage, the court feels free to refer to the action as one on the case without thinking it necessary to distinguish between assumpsit and the other forms of action on the case. Assumpsit is regularly referred to as an action on the case in assumpsit or an action on the case on a promise.2 Blackstone refers to "an action on the case for what is called the assumpsit or undertaking of the defendant."3 The abridgment makers made no effort to separate tort cases and contract cases under the general heading of action on the case until the latter part of the seventeenth century.4 As time passes on, however, greater stress is constantly being placed on the "assumpsit" and less on the trespass on the case, until, at last, assumpsit is taken out of the general class of trespass on the case and grouped with contract.
17 For discussions of the history of the law of contracts, see II Pollock & Maitland (2d Ed.), 184 et seq.; III Holdsworth's History of English Law, 318 et seq.; The History of Assumpsit, by James Barr Ames, 2 Harvard Law Review, 1, 53; 3 Select Essays in Anglo-American Legal History, 259; Parol Contracts Prior to Assumpsit, by James Barr Ames, 8 Harvard Law Review, 252; 3 Select Essays in Anglo-American Legal History, 304; The Origin of Assumpsit, by George F. Deiser, 25 Harvard Law Review, 428; Contracts in Early English Law, by Sir Frederick Pollock, 6 Harvard Law Review, 389; History of Contract, by John W. Salmond, 3 Law Quarterly Review, 166; 3 Select Essays in Anglo-American Legal History, 320.
18 The Surety, by Wm. H. Loyd, 66
University of Pennsylvania Law Review, 40.
1 Sidenham and Worlington's Case, 2 Leon. 224.
This is the result of the constant tendency at any given time to restrict the word "contract" to the rights which were protected by the earlier actions and to deny it to the rights which the newer actions were beginning to protect. See Sec. 34.
An additional action, for trying property rights in personal property, the action of trover, developed out of case. This was classed with the actions in tort as was case, while assumpsit has been classed as an action ex contractu.
2 It is called "action sur le case sur promise": Jackson's Case, Bendloes, 172.
3 Blackstone's Com. III, 157.
Two results followed from the inclination of the courts to classify assumpsit as a form of trespass on the case. What seems to us the anomaly of classifying breach of contract as a form of tort,5 was the very fact, however, that made it possible for assumpsit, on ultimately freeing itself from trespass on the case to take shape as a means of enforcing all breaches of enforceable agreements not already provided for by the actions of debt and covenant. After assumpsit became an established and distinct form of action, there was nothing in the technicalities of actions or procedure to prevent the enforcement by the courts of any promises which the law might hold enforceable. The persistent action of the courts in treating assumpsit as a form of trespass on the case, and the further fact that it finally took definite shape before rights were grouped on the basis of their inherent nature, caused the extension of the action of assumpsit to have a profound effect upon the classification of the law of contracts. When it was finally conceded that an assumpsit was a contract, the converse proposition that every right upon which assumpsit would lie was a contract, was assumed without discussion. The result is that to this day contract is regarded as including not only genuine contract, but also quasi-contract, in which are included some forms of tort. These questions are discussed in detail hereafter.6