May 3: Constitution Day in Poland and Japan, World Press Freedom Day.
- 1791 - The Polish Constitution of May 3, one of the earliest codified national constitutions in the world, was adopted by the Sejm.
- 1939 - Subhash Chandra Bose (pictured) formed the Forward Bloc of the Indian National Congress.
- 1945 - World War II: German ocean liner Cap Arcona, left to float defencelessly in the Bay of Lübeck with thousands of prisoners from various concentration camps on board, was attacked and sunk by RAF Typhoons.
- 1947 - A new Constitution of Japan went into effect.