S.C. Code Ann. § 1-11-320
The Board shall ensure that all state-owned motor vehicles are identified as such through the use of permanent state-government license plates and either state or agency seal decals. No vehicles shall be exempt from the requirements for identification except those exempted by the Board.
This section shall not apply to vehicles supplied to law enforcement officers when, in the opinion of the Board after consulting with the Chief of the State Law Enforcement Division, those officers are actually involved in undercover law enforcement work to the extent that the actual investigation of criminal cases or the investigators' physical well-being would be jeopardized if they were identified. The Board is authorized to exempt vehicles carrying human service agency clients in those instances in which the privacy of the client would clearly and necessarily be impaired.