Following the King’s abdication. The Extraordinary (Abdication) Sejm in Warsaw. 1668.
The Sejm was convened in June 1668. The pre-Sejm local gatherings were held on 23 July 1668. Prior to the convocation of the Sejm, the Primate of Poland, Stanisław Prażmowski, had sent to the nobles a letter of notification of the intent of King Jan Kazimierz (John II Casimir Vasa) to renounce his Polish crown. The Sejm session began on 27 August and lasted until 16 September 1668. The Marshal of the Chamber of Envoys was Stefan Sarnowski, the Chamberlain of Łęczyca. The Sejm dealt with issues of the abdication aftermath. Jan Kazimierz resigned his crown on the last day of the Sejm session.
See: J. A. Chrapowicki, Diariusz. Część Druga: lata 1665-1669 (The Sejm Record. Part Two: years 1665-1669), ed. A. Rachuba, T. Wasilewski, Warsaw 1988, pp. 435-447; S. Ochmann-Staniszewska, Z. Staniszewski, Sejm Rzeczypospolitej za panowania Jana Kazimierza Wazy. Prawo-doktryna-praktyka, (Sejm of the P-L Commonwealth during the reign of John Casimir Vasa. Law-doctrine-practice), vol. 1, Wrocław 2000, pp. 573-593; W. Kłaczewski, Abdykacja Jana Kazimierza. Społeczeństwo szlacheckie wobec kryzysu politycznego lat 1667-1668 (Abdication of John Casimir. The nobility faced with the political crisis of 1667-1668), Lublin 1993; H. Olszewski, Sejm Rzeczypospolitej epoki oligarchii (1652-1763). Prawo-praktyka-teoria-programy (Sejm of the age of oligarchy of the Polish-Lithuanian Commonwealth (1652-1763)). Law-practice-theory-programs, Poznań 1966. Ustawodawstwo (Legislation), see: Volumina Constitutionum, vol. 4, part. II, edited by Stanisław Grodziski, Marcin Kwiecień, Krzysztof Fokt, Preface by Wacław Uruszczak, Warsaw 2017, pp. 348-354.