S.C. Code § 25-1-1820
The National Guard shall not be subject to active duty other than training duty, except (a) in case of war, (b) in event or danger of invasion by a foreign nation, (c) there is a rebellion or danger of rebellion against the authority of the government of the United States, (d) the President issues orders to execute the laws of the United States, (e) for preventing, repelling or suppressing invasion, insurrection or riot, (f) for aiding civil officers in the execution of the laws, in which cases the Governor or local commander as provided for in Sections 25-1-1840 to 25-1-1880 shall order out for active service, by draft or otherwise, as many of the National Guard as necessity demands, or (g) during natural disaster or local emergency whenever the lives and property of the State's citizens are threatened.
S.C. Code § 25-1-1820