S.C. Code § 3-3-230
The lands, forts, fortifications and sites for the erection of forts on Sullivan's Island, James Island and Shutes Folly Island in Charleston County, as delineated in a plan of survey made by Robert Q. Pinckney on November 17 1846, under the direction of commissioners appointed under a resolution of 1845, have been ceded to the United States. Such lands, sites, forts and fortifications so ceded shall be exempt from any tax to be paid to this State. But all process, civil or criminal, issued under the authority of this State or any officer thereof shall and may be served and executed on any part of the lands, sites, forts and fortifications so ceded and on any person there being and implicated in matters of law. And nothing in such cession contained shall be construed to interfere with the rights and property of the citizens or so as to affect any of the streets, thoroughfares or public landings on said islands.
S.C. Code § 3-3-230