The National Day of 3 May commemorates the passing of the Government Act, known as the 3rd of May Constitution, by the Great Sejm in 1791. It was the first document of its kind in modern Europe and the second in the world, after the American Constitution.

The 3rd of May Constitution provided a vision and a programme of reforms for the Polish state. It changed the system of the state to a hereditary monarchy, abolished the liberum veto and limited the privileges of the nobility. An important solution was the introduction of the tripartite division of power into the legislative, executive and judiciary.

For Poles, the 3rd of May Constitution became a symbol of modern thinking about the state and responsibility for its fate. It is a document creating the identity of a sovereign nation.