Dahl got his Cand.jur. degree in 1928. From 1929 to 1933 he was hired as a deputy judge in Notodden. From 1933 to 1935 he was the deputy prosecutor in the same town. In 1935, he took a job as a deputy within the office of the County Governor of Vestfold. After World War II in 1945, he became took a leadership role for the whole county government. In 1948, when the new county governorOscar Torp left the county to serve in the Storting in Oslo, Dahl was named acting county governor in his absence. Torp served in the top levels of government including as Prime Minister of Norway, so he did not return to Vestfold to be county governor. When Torp died in 1958, Dahl was appointed as the new County Governor of Vestfold, a job he held until his death in 1964.