Born in Rødenes, he was chief editor of Nationen newspaper from 1913 to 1942 and chaired the Norwegian Press Association from 1931 to 1934.

[1][2] In the Norwegian parliamentary election of 1927 Aadahl was the third candidate on the list presented by the short-lived far-right National Legion, behind Karl Meyer (the party's leader) and Frøis Frøisland, and ahead of Jens Bratlie.

[3] In a press release, the National Legion stated that it had deliberately chosen "strong" personalities able to withstand the rigours of Norwegian politics.

[4] Frøisland denounced the list in a piece he wrote in Aftenposten, stating that neither he, Aadahl, nor Bratlie were willing candidates; they had not even been aware of their nomination.

Norwegian electoral law provided no legal grounds, however, for persons listed in the ballot to refuse their nomination.