[1] He was called to the bar by the Middle Temple in 1925, and was the pupil of Walter Monckton, before joining the chambers of Lord Wright at 5 Crown Office.

During World War II, Salmon was commissioned into the Royal Artillery in 1940, and was attached to the Eighth Army as a judge advocate.

He served as Recorder of Gravesend between 1947 and 1957, and was appointed a Commissioner of Assize for the Wales and Chester Circuit in 1955.

Salmon was appointed to the High Court in 1957 and assigned to the Queen's Bench Division, and received the customary knighthood.

On 10 January 1972, he was appointed a Lord of Appeal in Ordinary, being created, at the same time, a life peer with the title Baron Salmon, of Sandwich in the County of Kent.