Answer: William O. Douglas. Douglas, the New Deal liberal appointed by FDR in 1939, served more than 36 years, the longest tenure in Court history. In April 1970, House Minority Leader Gerald Ford, acting at the Nixon administration’s urging and widely seen as retaliating for the Senate’s defeat of nominees Clement Haynsworth and G. Harrold Carswell, launched a drive to impeach him, citing Douglas’s ties to a foundation, an article he’d published in a magazine Ford deemed obscene, and his unconventional lifestyle, including his four marriages. A House Judiciary subcommittee investigated for six months and cleared Douglas, and the effort collapsed. Read more here.