The article examines the main provisions of the conception of one of the most original Russian philosophers L. Petrazhitsky. He took an active political stance: he was among the originators of the cadet party and a member of its central committee; also he was a deputy of I State Duma. L. Petrazhitsky developed his ideological ideals in academic works and teaching activities. He considered a psychological factor to be the most important factor of jurisprudence and introduced the basic tenets of psychology of law according to the thesis that law is an inner relationship of Me and Another. The article also focuses on the L. Petrazysky’s understanding of policy of law as an academic discipline.