Was a member of Rada of the Belarus National Republic. Has published many books about Belarus, recognized the right of the people of Belarus to self-determination. Such books as "History of Belarusian (Krivich) book", "Short history of Belarus" propagandizes the idea.
In 1922-1925 he was the prime-minister of the BNR and the initiator of its actual dissolution. Lastouski was also a member of the Academy of sciences of Belarus. He was accused by case of "the Union for liberation of Belarus". He was sentenced to dispatch, but was seized and shot by the Soviets.
