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 Illinois, a judge may be disqualified from presiding over a case if there are provable facts that suggest a conflict of interest that could affect the judge's impartiality. The Illinois Code of Judicial Conduct provides specific circumstances under which a judge must disqualify themselves. These include situations where the judge has previously served as a lawyer in the matter, or if a lawyer with whom the judge previously practiced law served concerning the matter during their association. Additionally, a judge must disqualify themselves if they have a personal or fiduciary interest in the subject matter of the controversy, or if there is a close familial relationship (by affinity or consanguinity within the third degree) with any of the parties involved in the case. The process of a judge stepping down from a case due to potential conflict of interest is known as recusal, and it is based on maintaining the perception of impartiality. While disqualification is relatively rare, the standards are in place to uphold the integrity of the judicial process and ensure fair proceedings.