India is a federation with a parliamentary system governed under the Constitution of India—the country's supreme legal document. It is a constitutional republic and representative democracy, in which "majority rule is tempered by minority rights protected by law". Federalism in India defines the power distribution between the union and the states. The Constitution of India, which came into effect on 26 January 1950, originally stated India to be a "sovereign, democratic republic;" this characterisation was amended in 1971 to "a sovereign, socialist, secular, democratic republic". India's form of government, traditionally described as "quasi-federal" with a strong centre and weak states, has grown increasingly federal since the late 1990s as a result of political, economic, and social changes.