He was born in Kristiania[1] as a son of Fredrik Lange-Nielsen (1891–1980) and Laura Stang Lund (1893–1961).
He was hired in the Office of the Attorney General of Norway in 1951, and worked here until 1972, only interrupted by a few years in his own law firm.
Despite passing the normal retirement age, he was then an extraordinary judge in Oslo City Court from 1991 to 1995.
[1] His special fields included insurance law—he chaired Norsk forsikringsjuridisk avdeling from 1971 to 1982—and tort law, in which he lectured at the University of Oslo.
[1] He did however become better known for unveiling and overturning miscarriage of justice cases, an endeavor to which he dedicated his later life.