I examine what it is to have the ability to validly consent, and conclude that it is a Hohfeldian power. On that basis, I argue that the necessary conditions for the grant of consent must include all the necessary conditions for the exercise of a power. Using this idea, I attempt to isolate context-independent minimum conditions necessary for the grant of consent. I argue that the grant of consent requires an exercise of volition - the making of a choice - and that there exists no general requirement either that this choice be to invite a boundary crossing rather than merely to permit it, or that the choice invariably be accompanied by a performative token. Furthermore, I argue that the power to consent cannot be exercised so as to have retrospective effect. At most, the expectation of ratification may give rise to an entitlement to a supervening defence.