The closest definition under South Carolina law comes from Title 62 of the South Carolina Code. It states in part:
Unless otherwise apparent from the context, in this Code:
"(1) "Incapacitated person" means any person who is impaired by reason of mental illness, mental deficiency, physical illness or disability, advanced age, chronic use of drugs, chronic intoxication, or other cause (except minority) to the extent that he lacks sufficient understanding or capacity to make or communicate responsible decisions concerning his person or property."
A Durable Power of Attorney is valid upon signing by the principal and survives incapacity, but is subject to revocation by a principal at any time through the execution of a new Power of Attorney (which would revoke any prior existing POA) or notification to their agent(s) that they are revoking the POA, so long as they are able to contract to do so (to put it another way, they have to be competent enough to do so).
With a durable power of attorney, a principal creates an agency in another that continues despite the principal's later physical disability or mental incompetency. See § 62-5-501; see also 3 Am.Jur.2d Agency § 28 ("The only requirement is that an instrument creating a durable power contain language showing that the principal intends the agency to remain effective in spite of his later incompetency."). Moreover, in order for the principal to create the agency relationship in the first instance, the principal must have the mental capacity to contract. 3 Am.Jur.2d Agency § 12 ("A person who is not in a mental condition to contract and conduct his business is not in a condition to appoint an agent for that purpose."). Therefore, in order to execute or revoke a valid power of attorney, the principal must possess contractual capacity. See
In re Thames, 544 S.E.2d 854, 344 S.C. 564 (S.C.App. 2001 ; Timmons v. Starkey, 671 S.E.2d 101, 380 S.C. 590 (S.C.App. 2008).