At a time of an intriguing liberal constitutional experiment inthe Polish lands subordinated to the Russian Tsar, a liberalparliamentary group became active. It formed a kind of proto-opposition, focused in particular on accentuating unlawfulgovernmental activities and assessing parliamentary projects notonly from the point of view of their merits but, first and foremost,from the point of view of their compliance with the Constitutionof the Kingdom of Poland, octroyed in 1815 by Tsar Alexander.This article focuses on this activity and its ambiguous assessments