INDIA - CONSTITUTION January 26, 1930:   26 January was selected for the Republic Day because it was this day in 1930 when the Declaration of Indian Independence (Purna Swaraj) was proclaimed by the Indian National Congress. January 26, 1950:   The Constitution of India came into effect on this day. With its adoption, the Union of India officially became the Republic of India and it replaced the Government of India Act 1935 as the country's fundamental governing document.