Colo. Const. art. VI, § 18

Justices and judges of courts of record shall receive such compensation as may be provided by law, which may be increased but may not be decreased during their term of office and shall receive such pension or retirement benefits as may be provided by law. No justice or judge of a court of record shall accept designation or nomination for any public office other than judicial without first resigning from his judicial office, nor shall he hold at any other time any other public office during his term of office, nor hold office in any political party organization, nor contribute to or campaign for any political party or candidate for political office. No supreme court justice, judge of any intermediate appellate court, district court judge, probate judge, or juvenile judge shall engage in the practice of law. Justices, district judges, probate judges, and juvenile judges when called upon to do so, may serve in any state court with full authority as provided by law. Any county judge may serve in any other county court, or serve, as hereinafter may be authorized by law, in any other court, if possessing the qualifications prescribed by law for a judge of such county court, or other court, or as a municipal judge or police magistrate as provided by law, or in the case of home rule cities as provided by charter and ordinances.