These are lists of Article III United States federal judges by longevity of service.
Senate confirmation along with presidential appointment to an Article III court entails a lifelong appointment, unless the judge is impeached, resigns, retires, or assumes senior status.
The caseload of a senior judge may range from full to inactive.
[1][2] Data on judges' dates of service is maintained by the Federal Judicial Center.
[3] Their tenures generally differ from those found at list of United States Supreme Court justices by time in office by several days, as that page uses a justice's oath of office, rather than their date of commission, as their start date.