The article considers the problem of reaction of the greatest Polish opposition party to the post-1926 “Sanation”, namely, the right-wing National Democrat attitudes to the ideas of changes of the Polish Constitution of 1921. The author focuses on the King John Casimir University in Lviv milieu (mostly professors, but also graduates and those allied with these circles – lawyers and journalists). Among many advocates protesting against ruling party’s reforms of the Polish law was Władysław Tarnawski – the professor of English Philology at the University and one of the leaders of Lviv’s right wing. An analysis of the discourse on Polish law carried out by opposition parties against the post-May government allows to grasp the richness of Polish parliamentary life in the authoritarian period. Despite the numerous studies in Polish historiography dealing with the milieu of the National Democrats between 1918 and 1939, the Lviv branch of this party has been understudied.