On July 19, 1970, a group of about 1,500 members, including parliamentarians, academics, and others, gathered at the New Theatre of the Royal College, Colombo, and a Constitution Drafting Board was appointed under the chairmanship of Mr. Stanley Thilakaratne. The Constitution of Sri Lanka was adopted and enacted on May 22, 1972. Article 1 of the constitution declared Sri Lanka to be a free, sovereign, independent republic, and Article 2 declared it to be a unitary government. 

A presidency was established to replace the office of Governor-General William Gopallawa. Sections 4 and 5 stipulated that the government should be implemented by a National State Council consisting of representatives of the people. Furthermore, the name of Ceylon was changed to Sri Lanka by this constitution. When Sri Lanka became a republic in 1972, a new national emblem was created. Painter S.M. Seneviratne designed the state emblem. The President has the right to own and use the national emblem, which serves as the official seal of the state.

National Archives, 77/12, State Emblem

National Archives, Signed copy of 1972 Constitution