Although he was commissioned as an artillery captain, he also served as a judge advocate where he oversaw hundreds of courts-martial.

[8] Prettyman was nominated by President Harry S. Truman on September 12, 1945, to an Associate Justice seat on the United States Court of Appeals for the District of Columbia (United States Circuit Judge of the United States Court of Appeals for the District of Columbia Circuit from June 25, 1948) vacated by Judge Justin Miller.

Prettyman was a chairman of the Judicial Conference of the United States from 1959 to 1960, and was known for advocating for court expansion and improving juvenile adjudication.

[4] He established a program at Georgetown University to provide better legal assistance to indigent clients.

[8] In March 1997, the E. Barrett Prettyman Federal Courthouse in Washington, D.C. was named in his honor.