Recusal

Recusal refers to the the correct act of a judge or prosecutor being removed or voluntarily agreeing to step aside from a specific legal case typically due to conflict of interest or another good reason.

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Answers.com

A judge may recuse himself or herself, or refuse to participate in deciding a case, because of a special interest in the outcome that could influence his or her decision. The term recuse is derived from the Latin word recusare, which means “to refuse.” Chief Justice John Marshall, for example, recused himself in the case of Martin v. Hunter's Lessee (1816) because he had served as attorney to one of the parties (Martin) in an earlier phase of the case. In addition, he had a financial stake in the outcome of the case.

Wikipedia

Judicial disqualification, also referred to as recusal, refers to the act of abstaining from participation in an official action such as a legal proceeding due to a conflict of interest of the presiding court official or administrative officer. Applicable statutes or canons of ethics may provide standards for recusal in a given proceeding or matter. Providing that the judge or presiding officer must be free from disabling conflicts of interest makes the fairness of the proceedings less likely to be questioned.