Capacity legislation aims to protect individual autonomy and avoid undue paternalism as far as possible, partly through ensuring patients are not deemed to lack capacity because they make an unwise decision. To this end, the law employs a procedural test of capacity that excludes substantive judgments about patients' decisions. However, clinical intuitions about patients' capacity to make decisions about their treatment often conflict with a strict reading of the legal criteria for assessing capacity, particularly in psychiatry. In this article I argue that this tension arises because the procedural conception of capacity is inadequate and does not reflect the clinical or legal realities of assessing capacity. I propose that conceptualising capacity as having ‘recognisable reasons’ for a treatment decision provides a practical way of legitimately incorporating both procedural and substantive elements of decision-making into assessments of capacity.