Career
He was the father of Professor Olaf-Mihkel Klaassen of Tartu University.
justice of the Supreme Court of Estonia
He was the father of Professor Olaf-Mihkel Klaassen of Tartu University.
Klaassen was a member of the Electoral Committee that decided the Soviet-era appointment of Johannes Vares as Prime Minister by Konstantin Päts had been illegal and stated, that Jüri Uluots is Prime Minister acting as President of the Estonian Republic on April 20, 1944.