The General Sejm was the bicameral legislature of the Polish–Lithuanian Commonwealth. It was established by the Union of Lublin in 1569 following the merger of the legislatures of the two states, the Sejm of the Kingdom of Poland and the Seimas of the Grand Duchy of Lithuania. It was one of the primary elements of the democratic governance in the Commonwealth. The sejm was a powerful political institution that the king could not pass laws without its the approval.

The Polish–Lithuanian Commonwealth, formally known as the Kingdom of Poland and the Grand Duchy of Lithuania, or simply Poland–Lithuania, was a bi-confederal state, sometimes called a federation, of Poland and Lithuania ruled by a common monarch in real union, who was both King of Poland and Grand Duke of Lithuania. It was one of the largest and most populous countries of 16th- to 17th-century Europe. At its largest territorial extent, in the early 17th century, the Commonwealth covered almost 1,000,000 km2 (400,000 sq mi) and as of 1618 sustained a multi-ethnic population of almost 12 million. Polish and Latin were the two co-official languages, and Roman Catholicism served as the state religion.