S.C. Code Ann. § 25-1-2715: Challenges.

The military judge and members of a general or special court-martial may be challenged by the accused or the trial counsel for cause stated to the court. The military judge or, if none, the court, shall determine the relevancy and validity of challenges for cause, and may not receive a challenge to more than one person at a time. Challenges by the trial counsel shall ordinarily be presented and decided before those by the accused are offered.

Each accused and the trial counsel are entitled to one peremptory challenge, but the military judge may not be challenged except for cause.