Tenn. Code Ann. § 52-3-210: Lack of capacity

A person "lacks capacity" under this title for a decision about a routine medical, dental, or mental health treatment if:

(1) The person supported, due to an intellectual disability or mental impairment related to a developmental disability, is unable to make an informed decision about the routine medical, dental, or mental health treatment; and

(2) The incapacity is shown by the fact that the person is not able to understand the proposed procedure, its risks and benefits, or the available alternative procedures.