Gerard Quinn advances the proposition that there is a ‘legal culture’, which consists of unstated values and institutional expectations that underpin legal orders and constitute a ‘morality’ which enables law to be possible. He focuses on the United Nations Convention on the Rights of Persons with Disabilities (CRPD 2006), in particular on Article 12-Equal recognition before the law, to discuss the limited power (to date) that it has had in dislodging fundamental assumptions in legal cultures concerning legal capacity. Quinn uses this example to show how changes to ideas of legal personhood and mental capacity are difficult to achieve because of ‘legal fictions’ that lie at the heart of legal systems’ legal cultures. Quinn puts forward some ways to dislodge the historical ‘legal fictions’ embedded in legal culture.