The 52nd Constitutional Amendment Act of 1985 is a constitutional amendment that introduced the Anti-Defection Law in India. It was enacted to solve the problem of frequent political defections by elected representatives, a phenomenon often referred to as "Aaya Ram, Gaya Ram" politics, which caused significant governmental instability in the 1960s and 1970s. The Act received Presidential assent on February 15, 1985, and came into effect on March 18, 1985.
The core mechanism of the Act is the addition of the Tenth Schedule to the Constitution of India, which provides for the disqualification of Members of Parliament (MPs) and Members of State Legislatures (MLAs) on the ground of defection. A legislator can be disqualified under Paragraph 2 of the Tenth Schedule if they voluntarily give up the membership of their political party or if they vote or abstain from voting in the House contrary to any direction (whip) issued by their party, without prior permission and without the party condoning the action within fifteen days. The power to decide on a member's disqualification rests with the Chairman or the Speaker of the respective legislative house. The Act also made consequential changes to Article 101, Article 102, Article 190, and Article 191 of the Constitution, which deal with the vacation of seats and disqualification from membership.
The Act initially allowed for an exception where a 'split' in a party, involving one-third of its members, would not lead to disqualification. However, this provision was removed by the Constitution (Ninety-First Amendment) Act, 2003, which strengthened the law by retaining only the 'merger' exception, where a party can merge with another if not less than two-thirds of its legislators agree, as specified in Paragraph 4 of the Tenth Schedule. The Supreme Court, in the landmark judgment of Kihoto Hollohan v. Zachillhu (1992), upheld the constitutional validity of the law but ruled that the decision of the Speaker/Chairman is subject to judicial review on grounds like mala fide intent.