Q. I suspect that a state judge had private communications' with a group or its affiliates that was party to a major lawsuit.  Is the judge's private email or other correspondence subject to FOIA requests?

A.  In 2014, the South Carolina Attorney General issued a formal opinion addressing the applicability of South Carolina's Freedom of Information Act to the judiciary: 

Our Supreme Court has not yet addressed the question of whether the judiciary or a court is a "public body" for purposes of FOIA's applicability.  However, the court has stated that restrictions upon public access to judicial records "may be based on a statute or the court's inherent power to control its own records." Ex Parte Capital U-Drive It Inc. v. Beaver. 396 S.C. 1,10, 630 S.E. 2d 464, 469 (2006) (emphasis added).  Thus, based upon the foregoing authorities, our courts might well conclude that the records of the judicial branch are not subject to FOIA.

I am not aware of South Carolina court decisions concerning FOIA's applicability to private email accounts.  I can only suggest that you confer with a lawyer licensed in the state or, for the cost of a stamp, simply submit a FOIA request to the court and see what happens.