Salmiala completed his PhD in jurisprudence at the University of Helsinki in 1924 and became a career academic, serving as a professor of criminal law at the institution from 1925 to 1959.

[1] Salmiala also had an extensive career in the civil service, first as the deputy Parliamentary Ombudsman (1924–1928), then as a prosecutor (1926–1930) and finally as the head of the Criminal law institute (1955–1959).

[1] Salmiala's first involvement in politics came in 1928 when he was appointed to the board of directors of Uusi Suomi, the organ of the conservative National Coalition Party.

[2] An opponent of the violent tactics sometimes employed by the IKL due to his legal background he was nonetheless ideologically radical in contrast to the more conservative likes of Herman Gummerus and Erkki Räikkönen.

[1] Salmiala dropped out of politics after the Second World War and, as well as continuing his academic work, was a member of the Finnish Radio and Television Committee.