Capacity generally refers to a person’s ability to understand the pros, cons, and alternatives to a decision, as well as their ability to communicate their decision. It is specific to every question and every decision, so capacity should be considered at every step of a decision.
When it comes to healthcare decisions, everyone has the right to provide informed consent for their healthcare decisions. Capacity to consent to treatment should be assessed and documented for each treatment or plan of treatment. An individual is presumed to have capacity to make a healthcare decision, to give or revoke an advance directive, and to designate or disqualify a surrogate”.
Legal capacity refers to the right of people with disabilities to recognition everywhere as people before the law.
Mental capacity and legal capacity are not the same things. However, the two are often conflated, and thus a person is assumed to lack legal capacity because of a mental or intellectual disability. Such an assumption is discrimination and a violation of Article 12 of the Convention on the Rights of Persons with Disabilities.
Source:
Vanderbilt Kennedy Center for Excellence in Developmental Disabilities, Informed Consent in Adults with Intellectual or Developmental Disabilities, Health Care for Adults with Intellectual and Developmental Disabilities: Toolkit for Primary Care Providers (2017), http://vkc.mc.vanderbilt.edu/etoolkit/general-issues/informed-consent/