William O. Douglas became the 79th justice of the U.S. Supreme Court in 1939 at the relatively young age of 40.Nominated by President Franklin D. Roosevelt, Douglas was one of the youngest justices to be confirmed to the court. When Douglas retired on Nov. 12, 1975, after suffering a debilitating stroke, his term of 36 years, 209 days was and remains the longest term in the history of the Supreme Court.Early life and careerDouglas was born in Maine Township, Minn., on Oct. 16, 1898, to Julia Bickford (Fisk) and William …