[1][2] From 1942 to 1950, Murphy served as an Assistant United States Attorney for the Southern District of New York.
[2] He became head of the criminal division in 1944 and from 1949 to 1950 served as prosecutor in the two perjury trials of Alger Hiss, winning a conviction in the second after the first ended in a hung jury.
[2] Murphy presided at a jury trial that determined that the Swedish sex film I Am Curious (Yellow) was obscene.
He called it "repulsive and revolting" and ordered it confiscated, but was later overruled by the United States Court of Appeals for the Second Circuit.
Serving by designation on the United States District Court for the District of Connecticut, he presided at the trial of Vladimir Samarin, a former Yale University instructor, who was accused of lying about his activities as a Nazi propagandist during World War II both when immigrated and when seeking United States citizenship.