One way of increasing the supply of organs available for transplant would be to switch to an opt-out system of donor registration. This is typically assumed to operate on the basis of presumed consent, but this faces the objection that not all of those who fail to opt out would actually consent to the use of their cadaveric organs. This paper defuses this objection, arguing that people's actual, explicit or implicit, consent to use their organs is not needed. It borrows David Estlund's notion of 'normative consent' from the justification of political authority and applies it to the case of organ donation. According to this idea, when it is wrong to withhold consent to something, the moral force of that lack of consent may be null and void. If it is wrong of a person to refuse to donate their cadaveric organs to others, then it may be that their actual consent is not needed. This supports an opt-out system, which provides protection for those who have genuine reasons to refuse donation, and spares the worries as to what the deceased would actually have wanted.