<P> In Berubari Case (1960), The amendability & the Significance of the same came to the force . An important & very interesting question was raised relating to the powers of the Parliament to cede Indian territory to a foreign country, as an interpretation of the Article 3 . Supreme Court had held that the power of Parliament to diminish the area of a state as guaranteed in article 3 of the Constitution does not cover cession of the Indian territory to a foreign country . Hence, Indian territory can be ceded to a foreign country only by means of amendment of the Constitution under the Article 368 . Consequently, the 9th Constitutional Amendment Act, 1960 was enacted to transfer the Berubari Union to Bangladesh (erstwhile East Pakistan). Supreme Court also held the view that Preamble cannot be a part of the constitution but later in Kesavananda Bharati Case (1973), the Supreme Court gave a comprehensive verdict . It said that Preamble is Part of Constitution and is subject to the amending power of the parliament as any other provisions of the Constitution, provided the basic structure of the constitution is not destroyed . </P> <P> It has been clarified by the Supreme Court of India that being a part of Constitution, the Preamble can be subjected to Constitutional Amendments exercised under article 368, however, the basic structure cannot be altered . </P> <P> The preamble has been amended only once so far . On 18 December 1976, during the Emergency in India, the Indira Gandhi government pushed through several changes in the Forty - second Amendment of the constitution . A committee under the chairmanship of Sardar Swaran Singh recommended that this amendment be enacted after being constituted to study the question of amending the constitution in the light of past experience . Through this amendment the words "socialist" and "secular" were added between the words "Sovereign" and "democratic" and the words "unity of the Nation" were changed to "unity and integrity of the Nation". </P>

When was the expression unity and integrity of the nation added in the preamble to the constitution