In July 1955, d'Alquen was sentenced by a Berlin Denazification court to pay a fine of 60,000 DM, followed by a loss of pension rights for three years. He was found guilty of having played a significant role in war propaganda and incitement against churches, Jews and foreigners in the Nazi state. After further investigation of d'Alquen's income from this activity, he was sentenced to pay another fine of 28,000 DM in January 1958.