Assumpsit ("he has undertaken", from Latin, assumere),[1] or more fully, action in assumpsit, was a form of action at common law used to enforce what are now called obligations arising in tort and contract; and in some common law jurisdictions, unjust enrichment. The origins of the action can be traced to the 14th century, when litigants seeking justice in the royal courts turned from the writs of covenant and debt to the trespass on the case.[2]