The United Nations Convention on the Rights of Persons with Disabilities (CRPD), which entered into force in 2008, has been ratified or acceded to by 183 countries. The author examines the elusive juridical notion of “legal capacity” set out in Article 12 of the Convention and the concomitant concept of “supported decision-making” (SDM). States Parties to the CRPD reaffirm that persons with disabilities have the right to “recognition everywhere as persons before the law” and “enjoy legal capacity on an equal basis with others” in all aspects of life. Parties also agree to “take appropriate measures to provide access by persons with disabilities to the support they may require in exercising their legal capacity” and to ensure that these measures “provide for appropriate and effective safeguards to prevent abuse in accordance with international human rights law.” Some signatories registered Declarations or Reservations regarding Article 12, on the distinction between rights and performance or capacity to act. This includes nations where Islamic influence is strong. SDM is cherished in the disability community as the antidote to guardianship and other antiquated frameworks for governing the lives of people with mental health, psycho-social and intellectual disabilities. References to disability (and cognitive disability in particular) are found in the Qur’an and other Islamic texts and in contemporary commentary and legislation in Muslim majority nations. Closely intertwined with the concept of legal agency is the last core Article 12 element: implementation of decision-making with support.  The analysis in this article relies on CRPD Committee commentary as well as cultural, religious and secular interpretations, and on reflections based on the author’s personal experience.