Czeslaw Znamierowski (1888-1967) is an author of an original theory of law, in which he developed the concept of social phenomena. He was analyzing the ways of constructing and reasoning of moral and legal norms. His works play important role in the development of Polish philosophy of law. Czeslaw Znamierowski represented critical approach to German Idealism. However one can find links between his views and Kant's practical philosophy and especially Kant's deontological ethics. In this context one can point to the relations between Znamierowski's concept of common goodwill and Kant's practical imperative.