Tennessee Code Title 33. Mental Health and Substance Abuse and Intellectual and Developmental Disabilities § 33-3-102

(a) No person with mental illness, serious emotional disturbance, or developmental disability hospitalized or admitted, whether voluntarily or involuntarily, or ordered to participate in nonresidential treatment or service under this title, shall, solely by reason of the hospitalization, admission, or order, be denied the right to dispose of property, execute instruments, make purchases, enter into contractual relationships, give informed consent to treatment, and vote, unless:

(b) No person shall make decisions for a service recipient on the basis of a claim to be the service recipient's conservator, legal guardian, guardian ad litem, caregiver under title 34, chapter 6, part 3, or to be acting under a durable power of attorney for health care under title 34, chapter 6, part 2, until the person has presented written evidence of the person's status.