Tadeusz Matuszewicz was a politician, civil servant, and statesman. He lived at the turn of the 18th and 19th centuries, taking part in several important events of this period, the most significant of which were participation in the drafting of the Constitution of 3 May 1791 and its adoption, and holding the post of the Minister of Treasury both in the Duchy of Warsaw and the Kingdom of Poland. He also took part in the Civil Reform Committee, which prepared changes to the administrative system. The details of Matuszewicz’s biography should therefore illuminate a number of public and legal issues of the era. The reviewed book of Dominika Rychel-Mantur is intended as a biography of Matuszewicz’s public activities. In fact, it only slightly expands the knowledge concerning some aspects of Matuszewicz’s life between 1809 and 1815. Other public activities are either omitted or superficially elaborated. The author did not use the basic archival sources and omitted important pieces of literature on the subject. Many of the findings presented against the source materials used turn out to be untrue due to their misunderstanding or misreading. Unfortunately, Dominika Rychel-Mantur’s book can hardly be regarded as successful.