S.C. Code § 23-1-15
Any real property which is used as a parking lot and is open to use by the public for motor vehicle traffic shall be within the police jurisdiction with regard to the unlawful operation of motor vehicles in such parking lot.
Such parking lots shall be posted with appropriate signs to inform the public that the area is subject to police jurisdiction with regard to unlawful operation of motor vehicles. The extension of police jurisdiction to such areas shall not be effective until the signs are posted.
In any such area the law enforcement agency concerned shall have the authority to enforce all laws or ordinances relating to the unlawful operation of motor vehicles which such agency has with regard to public streets and highways immediately adjoining or connecting to the parking area.
S.C. Code § 23-1-15