112 Justices have served on the Supreme Court of the United States, the highest judicial body in the United States. Justices have life tenure, and so serve until they die in office, resign or retire, or are impeached and removed from office (which has never happened; the one impeached Justice was acquitted). Of the current Chief Justice and eight Associate Justices, the longest serving is Justice Antonin Scalia, for a term to date of days ( years). For the 103 non-incumbent justices, the mean length of service was 6,112 days (16.7 years) with a standard deviation of 3,620 days (9.9 years). The median length of service was 5,740 days (15.7 years). Their period of service ranges from William O. Douglas's 13,358 days (36 years) on the Court to the 163–day tenure of Thomas Johnson.