By the 1960 military coup on 27 May, the 11th Parliament was abolished. On 9 July 1961, a referandum was held for a new constitution, and on 15 October 1961 Turkey returned to democratic political system. On 4 April 1963, a public holiday was enacted to commemorate the new constitution. The holiday was on the 27 May. The public holiday was abolished on 17 March 1981 following the 12 September 1980 military coup.