In order to qualify for the office of chief judge, a judge must have been in active service on the court for at least one year, be under the age of 65, and have not previously served as chief judge. A vacancy in the office of chief judge is filled by the judge highest in seniority among the group of qualified judges. The chief judge serves for a term of seven years or until age 70, whichever occurs first. The age restrictions are waived if no members of the court would otherwise be qualified for the position. Unlike the Chief Justice of the United States, a chief judge returns to active service after the expiration of his or her term and does not create a vacancy on the bench by the fact of his or her promotion. See 28 U. S. C. § 45.