A total of 113 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 they 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). The longest - serving member of the current court is Associate Justice Anthony Kennedy, with a term to date of 7004108520000000000 ♠ 10,852 days (29 years). For the 104 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.
who is currently the longest serving supreme court justice
Anthony Kennedy