S.C. Code Ann. § 59-67-210: School bus passing another school bus unlawful.

It shall be unlawful for any person operating a school bus to pass another school bus unless the lead bus is in a stopped position and the driver of the lead bus has signalled to the operator of the bus in the rear that it is safe to pass. Any person violating the provisions of this section shall be guilty of a misdemeanor and, upon conviction, shall be fined the sum of one hundred dollars or be imprisoned for a term of thirty days.