The Delimitation Bill is a legislative proposal (Bill) introduced in Parliament that, upon being passed, becomes a Delimitation Act. Its purpose is to provide for the readjustment of the allocation of seats in the House of the People (Lok Sabha) and the total number of seats in the Legislative Assembly of each State, and to divide each State into territorial constituencies.
The concept originates from the constitutional mandate in Article 82 for the Parliament to enact a Delimitation Act after every Census, and Article 170 for the adjustment of State Assembly constituencies. The process was created to solve the problem of unequal representation by ensuring that each constituency represents a roughly equal share of the population, upholding the principle of "one person, one vote, one value". Delimitation Commissions were established under Acts in 1952, 1962, 1972, and 2002.
The mechanism works by establishing a high-powered Delimitation Commission, typically chaired by a retired Supreme Court judge, which redraws constituency boundaries based on the latest Census data. The Commission's orders are final and cannot be called into question in any court, as per Article 329(a) of the Constitution. The process also includes determining the seats to be reserved for Scheduled Castes (SCs) and Scheduled Tribes (STs) under Articles 330 and 332.
The process was historically frozen by the 42nd Amendment (1976) to encourage population control, and this freeze was extended by the 84th Amendment (2002) until the first Census after 2026. A significant recent change is the proposed Delimitation Bill, 2026, which is intended to repeal and replace the Delimitation Act, 2002. This Bill, along with the proposed Constitution (131st Amendment) Bill, 2026, aims to remove the decades-long freeze and allow a new delimitation exercise to proceed based on a Census chosen by Parliament, potentially the 2011 Census, which would fundamentally restructure the electoral landscape.