Former Estonian Supreme Court Justice and member of the country's Electoral Committee.
He became a Supreme Court Justice in 1924.
He helped the Estonian Electoral Committee come to the conclusion that the Soviet-era appointment of Johannes Vares as Prime Minister was illegal.
His son, Olaf-Mihkel Klaassen, became a professor at Tartu University.
He was active in Estonia during the same period as fellow politician Juri Uluots.