S.C. Code § 44-77-30
If a person eighteen years of age or older adopts a declaration that is substantially in the form provided in Section 44-77-50, whether executed before or after an amendment is made to the form, and that on its face is duly executed, witnessed, and authenticated as provided in Section 44-77-40 or on its face is in compliance with the law of the state of the declarant's domicile at the time that the declaration is adopted, if the declaration provided for by the law expresses an intent that is substantially the same as the intent of the declaration provided in Section 44-77-40, and the person's present condition is certified to be terminal or to be in a state of permanent unconsciousness by two physicians who personally have examined the declarant, one of whom is the declarant's attending physician, and the other of whom is a physician other than the attending physician, then life-sustaining procedures may be withheld or withdrawn upon the direction and under the supervision of the attending physician. A certification based upon a diagnosis of permanent unconsciousness may not be made until the declarant has remained unconscious for at least ninety consecutive days, or at any time if the declarant has experienced massive destruction or atrophy of the cortex as evidenced by neurodiagnostic studies or gross inspection of the brain, or some other characteristic of the declarant's condition allows a diagnosis of permanent unconsciousness to be made with a high degree of medical certainty.
All patients with life-threatening conditions that are diagnosed as terminal or in a state of permanent unconsciousness must be administered active treatment for at least six hours following the diagnosis before the physician may give effect to a declaration.
S.C. Code § 44-77-30