Exercising legal capacity refers to engaging in legal transactions and relationships and is essential for the full inclusion of people with disabilities in society. The United Nations Convention on the Rights of Persons with Disabilities has enumerated the right to legal capacity on an equal basis and has created a state obligation to provide access to support for the exercise of legal capacity. This article examines the use of assistive devices as support for decision-making in exercising legal capacity for individuals with physical and cognitive impairments; for example, the use of voice recognition programmes, screen readers, and screen enlargement applications to support people with mobility and sensory impairments to use online portals essential for legal actions such as banking. It also discusses the experimental use of cognitive assistance, including computer or electrical assistive devices, to facilitate communication for people with cognitive impairments including those with no external signs of consciousness. It highlights the diversity of options for ‘support for the exercise of legal capacity’ showing how they can assist people with various disabilities. Finally, the article examines the boundaries of the state obligation to provide such support, including issues of practical implementation and resource allocation.