ASSUMPSIT (“he has undertaken,” from Lat. assumere), a word applied to an action for the recovery of damages by reason of the breach or non-performance of a simple contract, either express or implied, and whether made orally or in writing. Assumpsit was the word always used in pleadings by the plaintiff to set forth the defendant’s undertaking or promise, hence the name of the action. Claims in actions of assumpsit were ordinarily divided into (a) common or indebitatus assumpsit, brought usually on an implied promise, and (b) special assumpsit, founded on an express promise. Assumpsit as a form of action became obsolete after the passing of the Judicature Acts 1873 and 1875. (See further Contract; Pleading and Tort.)