This article examines non-statutory executive powers, which are commonly employed in the modem state but rarely studied as a distinct concept. The article assesses three treatments of these powers available in current English public law-prerogative, common law powers which rely on analogies between the state and legal persons, and judicial review-and argues that they fail to provide a proper balance between legality and need. Royal prerogative connotes a shrinking reservoir of ancient powers, while non-statutory powers respond to unexpected futures and statute's intrinsic eventual failings. Analogies to legal persons fail to address the particularities of executive powers. Judicial review provides only a partial solution, since absence of parliamentary approval is not, in itself, ground for special treatment of executive action. The author joins calls for theoretization of public law and advances a model of executive powers that draws on a composite theory of the executive branch and its functions.