Constitution of 3 May 1791
The Constitution of 3 May 1791, titled the Government Act, was a written constitution for the Polish–Lithuanian Commonwealth that was adopted by the Great Sejm that met between 1788 and 1792. The Commonwealth was a dual monarchy comprising the Crown of the Kingdom of Poland and the Grand Duchy of Lithuania; the new constitution was intended to address political questions following a period of political agitation and gradual reform that began with the Convocation Sejm of 1764 and the election that year of the Commonwealth's last monarch, Stanisław August Poniatowski.
Source: Wikipedia — Constitution of 3 May 1791 (CC BY-SA 4.0)