Code of Civil Procedure 170.6 provides the statutory basis to disqualify a judge from hearing a proceeding. A peremptory challenge is usually made by filing an affidavit or declaration under penalty of perjury that the judge is prejudiced against a party or attorney for a party using a locally approved form.
If the affidavit is duly presented (timely), no further act or proof is required and a new judge must be assigned, except that no party or attorney shall be permitted to make more than one such motion in any action or proceeding, and if there are multiple plaintiffs or defendants, only one motion for each side may be made.
What about the circumstance where an appeal is taken from a judgment or interim order? In that circumstance, section 170.6 provides that a successful party on appeal may exercise a second peremptory challenge provided the appeal is from a final judgment, but not if the appeal is from an interim order.
The case is McNair v. Superior Court (National Collegiate Athletic Assn.): “…[W]e hold that Code of Civil Procedure section 170.6, subdivision (a)(2) allows a party to exercise a second peremptory challenge only after prevailing in an appeal from a final judgment, but not following reversal of an interim decision.”