A judge may be disqualified from hearing or presiding over a matter in which provable facts suggest the judge has a disqualifying conflict of interest. The related legal process of recusal of a judge is generally based on the perception of impartiality due to circumstances that suggest a conflict of interest—but not to the same degree as the facts that establish disqualification.

The standards for disqualification of a judge vary from state to state, and disqualification is rare. But a judge is generally disqualified in any proceeding in which:

(1) the judge has served as a lawyer in the matter in controversy, or a lawyer with whom the judge previously practiced law served during such association as a lawyer concerning the matter;

(2) the judge knows that, individually or as a fiduciary, the judge has an interest in the subject matter in controversy; or

(3) either of the parties may be related to the judge by affinity or consanguinity within the third degree.

In South Dakota, a judge may be disqualified from presiding over a case if there are provable facts that suggest a conflict of interest, which could compromise the judge's impartiality. According to South Dakota Codified Laws (SDCL), a judge is typically disqualified from a proceeding if: (1) the judge has previously served as an attorney in the matter in question, or if an attorney with whom the judge has previously practiced law served in relation to the matter during their association; (2) the judge has a personal or fiduciary interest in the subject matter of the controversy; or (3) a party to the proceeding is related to the judge by blood or marriage within the third degree. The process of a judge stepping down from a case due to potential conflict of interest is known as recusal. While disqualification is not common, it is an important mechanism to ensure fairness and maintain public confidence in the judicial system.