Assumpsit

The term 'assumpsit' is part of the origins of contract law. It is a Latin word (from 'assumere') meaning ‘he has undertaken’, historically used in pleadings by the plaintiff to set out the defendant's obligation.

Originally it was an action at common law, describing an action to recover damages for breach or non-performance of a simple contract (not under seal), that is, a party taking on an obligation, express or implied, but then failing to perform that obligation.

Historically, actions in contract and in tort were both derived from trespass, whereas actions for breach of a deed were based upon an action on the covenant. Actions for breach of contract were based on assumpsit and actions in tort were ex delicto.

In the seventeenth century the courts began to draw procedural but not substantive distinctions between assumpsit and actions ex delicto. These distinctions became substantive differences during the nineteenth century, reflecting the political social and economic philosophy of 'laissez-faire', which emphasised the importance of the legal doctrines of freedom of contract and sanctity of contract.