Politics in India take place within the framework of its constitution, as India is a federal parliamentary democratic republic in which the President of India is the head of state and the Prime Minister of India is the head of government. India follows the dual polity system, i.e. a double government which consists of the central authority at the centre and states at the periphery. The constitution defines the organisation, powers and limitations of both central and state governments, and it is well-recognised, rigid and considered supreme; i.e. laws of the nation must conform to it. There is a provision for a bicameral legislature consisting of an Upper House, i.e. Rajya Sabha, which represents the states of the Indian federation and a lower house i.e. Lok Sabha, which represents the people of India as a whole. The Indian constitution provides for an independent Judiciary which is headed by the Supreme Court. The court's mandate is to protect the constitution, to settle disputes between the central government and the states, inter-state disputes, and nullify any central or state laws that go against the constitution.