Ethical and legal discourse pertaining to the ability to consent to treatment and research in England operates within a dualist framework of “competence” and “capacity”. This is confusing, as while there exists in England two possible senses of legal capacity – “first person” legal capacity and “delegable” legal capacity, currently neither is formulated to bear a necessary relationship with decision-making competence. Notwithstanding this, judges and academic commentators frequently invoke competence to consent in discussions involving the validity of offering or withholding (...) consent as a synonym for legal capacity to consent. I argue that this gives rise to a conflation, jeopardising clarity and consistency in law. This is somewhat less problematic in instances of “first-person” legal capacity that are heavily informed by criteria for decision-making competence than in the second sense of legal capacity, which is qualitatively different from decision-making competence, or with first-person legal capacity when defined in different terms from competence. The paper concludes by proposing that the soundest resolution to this problem is by making decision-making competence a necessary and sufficient condition of first-person legal capacity, affording a more scrupulous distinction between the two different forms of legal capacity that exist. (shrink)