The word recuse or recusal, disqualify or disqualification relates to a judge being removed from presiding over a case.
The judge can self-recuse or self-disqualify, or a party to the case can request that the judge be removed.
If the party makes a motion, it’s ruled upon like any motion in the case, and under certain procedural rules, appellate review of the judge’s decision can be sought. In Minnesota, the party whose motion to disqualify is denied by the sitting judge, must be quickly brought to the attention of the Court of Appeals (instead of waiting to appeal the issues at the end of the case).
The rules of judicial conduct require recusal/disqualification in certain situations. The federal rules and statutes govern recusals of federal judges. See Code of Conduct for United States Judges.
For state judges in Minnesota see Canon 2, and Rule 2.11,
(A) A judge shall disqualify himself or herself in any proceeding in which the judge’s impartiality might reasonably be questioned, including but not limited to the following circumstances:
(1) The judge has a personal bias or prejudice concerning a party or a party’s lawyer, or personal knowledge of facts that are in dispute in the proceeding.
(2) The judge knows that the judge, the judge’s spouse, a person with whom the judge has an intimate relationship, a member of the judge’s household, or a person within the third degree of relationship to any of them, or the spouse or person in an intimate relationship with such a person is:
(a) a party to the proceeding, or an officer, director, general partner, managing member, or trustee or a party;
(b) acting as a lawyer in the proceeding;
(c) a person who has more than a de minimis interest that could be substantially affected by the proceeding; or
(d) likely to be a material witness in the proceeding.
(3) The judge knows that he or she, individually or as a fiduciary, or the judge’s spouse, parent, child, or any other member of the judge’s family residing in the judge’s household, a person with whom the judge has an intimate relationship, or any other member of the judge’s household, has an economic interest in the subject matter in controversy or in a party to the proceeding.
(4) The judge, while a judge or a judicial candidate, has made a public statement, other than in a court proceeding, judicial decision, or opinion, that commits or appears to commit the judge to reach a particular result or rule in a particular way in the proceeding or controversy.
(5) The judge:
(a) served as a lawyer in the matter in controversy, or was associated with a lawyer who participated substantially as a lawyer in the matter during such association;
(b) served in governmental employment, and in such capacity participated personally and substantially as a lawyer or public official concerning the proceeding, or has publicly expressed in such capacity an opinion concerning the merits of the particular matter in controversy;
(c) was a material witness concerning the matter; or
(d) previously presided as a judge over the matter in another court.
(B) A judge shall keep informed about the judge’s personal and fiduciary economic interests, and make a reasonable effort to keep informed about the personal economic interests of the judge’s spouse, a person with whom the judge has an intimate relationship, and any member of the judge’s household.
(C) A judge subject to disqualification under this Rule, other than for bias or prejudice under paragraph (A)(1), may disclose on the record the basis of the judge’s disqualification and may ask the parties and their lawyers to consider, outside the presence of the judge and court personnel, whether to waive disqualification. If, following the disclosure, the parties and lawyers agree, without participation by the judge or court personnel, that the judge should not be disqualified, the judge may participate in the proceeding. The agreement shall be incorporated into the record of the proceeding.