The Second Polish Republic adopted the March Constitution on 17 March 1921, after ousting the occupation of the German/Prussian forces in the 1918 Greater Poland Uprising, and avoiding conquest by the Soviets in the 1920 Polish-Soviet War. The Constitution, based on the French one, was regarded as very democratic. Among others, it expressly ruled out discrimination on racial or religious grounds.

It was partially adjusted by the 1926 August Novelization, and superseded by the Polish Constitution of 1935 (April Constitution).