In the Commonwealth of the Two Nations, significant legal texts were implemented under the rule of King Stanislaw August, the most important being the Constitution of May 3, 1791, adopted during the Four-Year Sejm (1788-1792). Its framers faced numerous challenges, first, because then only nobles were considered as constituting the Republic, one was to define who should be considered as a member of the People, who could be elected deputy to the Sejm, and at which condition. Second, since the 1569 Union of Lublin the Commonwealth is made of two distinct states: Poland (the Crown) and the Grand-Duchy of Lithuania, drafters had to handle Lithuanian statehood in a Constitution, which was primarily seen as a way to enhance unification of the two nations. Third, the Grand-Duchy of Lithuania having its own legislation, enclosed in the Lithuanian statute, (adopted in 1529, followed with a Second Statute in 1566, and a Third Statute in 1588), the question of its maintaining or not too had to be taken into consideration by framers. We hope that considering how these different issues were handled will shed a new light on the permanence of Lithuanian laws and political tradition in the May 3 Constitution.