First sejm in 17th century. General sejm in Warsaw. 1601.
The sejm was convened in October 1600, as a result of a previous, ineffective sejm that took place in the same year. The pre-sejm sejmiks were held in December 1600 and January 1601. The sejm debated from 7 February to 13 March 1601. Jan Zbigniew Ossoliński, the marshal of the tribunal (and later a voivode), was elected the marshal of the sejm. During the proceedings the examination of royal demesnes was voted for.
See: B. Janiszewska-Mincer, Rzeczpospolita Polska w latach 1600-1603 [The Commonwealth in years 1600-1603], Bydgoszcz 1984. Ustawodawstwo zob. Volumina Constitutionum, T. 2, cz. 2, Design and layout prepared by S. Grodziski, Warszawa 2008, s. 268-321.