After the Norman conquest all ordinary actions were begun by a writ issuing from the king, and ordering the defendant to be summoned before the court to answer the plaintiff.  These writs were issued as a matter of course, in the various well-known actions from which they took their names.  There were writs of debt and of covenant; there were writs of trespass for forcible injuries to the plaintiff’s person, or to property in his possession, and so on.  But these writs were only issued for the actions which were known to the law, and without a writ the court had no authority to try a case.  In the time of Edward I. there were but few of such actions.  The cases in which you could recover money of another fell into a small number of groups, for each of which there was a particular form of suing and stating your claim.

These forms had ceased to be adequate.  Thus there were many cases which did not exactly fall within the definition of a trespass, but for which it was proper that a remedy should be furnished.  In order to furnish a remedy, the first thing to be done was to furnish a writ.  Accordingly, the famous statute of 13 Edward I., c. 24, authorized the office from which the old writs issued to frame new ones in cases similar in principle to those for which writs were found, and requiring like remedy, but not exactly falling within the scope of the writs already in use.

Thus writs of trespass on the case began to make their appearance; that is, writs stating a ground of complaint [275] to a trespass, but not quite amounting to a trespass as it had been sued for in the older precedents.  To take an instance which is substantially one of the earliest cases, suppose that a man left a horse with a blacksmith to be shod, and he negligently drove a nail into the horse’s foot.  It might be that the owner of the horse could not have one of the old writs, because the horse was not in his possession when the damage was done.  A strict trespass property could only be committed against the person in possession of it.  It could not be committed by one who was in possession himself. 1 But as laming the horse was equally a wrong, whether the owner held the horse by the bridle or left it with the smith, and as the wrong was closely analogous to a trespass, although not one, the law gave the owner a writ of trespass on the case. 2

An example like this raises no difficulty; it is as much an action of tort for a wrong as trespass itself.  No contract was stated, and none was necessary on principle.  But this does not belong to the class of cases to be considered, for the problem before us is to trace the origin of assumpsit, which is an action of contract.  Assumpsit, however, began as an action of trespass on the case, and the thing to be discovered is how trespass on the case ever became available for a mere breach of agreement.