Iowa constitution
Article V
Section 17

Members of all courts shall have such tenure in office as may be fixed by law, but terms of supreme court judges shall be not less than eight years and terms of district court judges shall be not less than six years. Judges shall serve for one year after appointment and until the first day of January following the next judicial election after the expiration of such year. They shall at such judicial election stand for retention in office on a separate ballot which shall submit the question of whether such judge shall be retained in office for the tenure prescribed for such office and when such tenure is a term of years, on their request, they shall, at the judicial election next before the end of each term, stand again for retention on such ballot. Present supreme court and district court judges, at the expiration of their respective terms, may be retained in office in like manner for the tenure prescribed for such office. The general assembly shall prescribe the time for holding judicial elections.