S.C. Code Ann. § 41-7-20: Agreement between employer and labor organization denying nonmembers right to work or requiring union membership.

Any agreement or combination between any employer and any labor organization whereby persons not members of such labor organizations shall be denied the right to work for such employer or whereby such membership is made a condition of employment, or of continuance of employment by such employer, or whereby any such union or organization acquires an employment monopoly in any enterprise, is hereby declared to be against public policy, unlawful and an illegal combination or conspiracy.