ENThe article discusses the legislative output of the Sejm of 1615. There is a common opinion in reference to the seventeenth century that the constitution was a concordant conclusion of the three parliamentary estates combined with a promulgation. However, the conducted analysis reveals that despite the lack of agreement to the conclusion of the 1615 Sejm, it adopted normative acts: both at the beginning and at the end of the parliamentary proceedings. In addition, a new type of law sources has been characterised, i. e. resolutions of the Chamber of Deputies, which at that time were equal in rank to Sejm constitutions.