Section 150 in The Representation Of The People Act, 1951.
150. Casual vacancies in the State Legislative Assemblies.
When the seat of a member elected to the Legislative Assembly of a State becomes vacant or is declared vacant or his election to the Legislative Assembly is declared void, the Election Commission shall, subject to the provisions of sub- section (2), by a notification in the Official Gazette, call upon the Assembly constituency concerned to elect a person for the purpose of filling the vacancy so caused before such date as may be specified in the notification, and the provisions of this Act and of the rules and orders made thereunder shall apply, as far as may be, in relation to the election of a member to fill such vacancy.
If the vacancy so caused be a vacancy in a seat reserved in any such constituency for the Scheduled Castes or for any Scheduled Tribes, the notification issued under sub- section (1) shall specify that the person to fill that seat shall belong to the Scheduled Castes or to such Scheduled Tribes, as the case may be.