Assumpsit

Assumpsit [he undertook] (to pay or perform) as set forth of the defendant by the plaintiff in the ancient pleading. The action of assumpsit (which, as a technical name, fell into desuetude with the passing of the Judicature Acts, 1873 and 1875, and is now generally superseded by the term 'action for breach of contract') was an action on the case, grounded originally on damages for breach of a promise; it lies for the recovery of damages for loss or injuries sustained by reason of the breach or non-performance of a promise, either express or implied, not under seal, but founded on a proper consideration. See PLEADING.

The ordinary division of this action was into (1) common or indebitatus assumpsit, brought for the most part on an implied promise; and (2) special assumpsit, founded on an express promise, Steph. Plead., 7th ed., 11, 13.