The 10th Schedule is a provision of the Indian Constitution, commonly known as the Anti-Defection Law. It was introduced by the 52nd Amendment Act in 1985 to curb the problem of political defections, which had caused significant instability in governments, famously characterized by the phrase "Aaya Ram, Gaya Ram". The law was enacted to ensure that elected representatives remained loyal to the party on whose ticket they won and to prevent defections motivated by personal gain or material benefits.
The mechanism of the 10th Schedule provides for the disqualification of Members of Parliament (MPs) and Members of State Legislatures (MLAs) on four main grounds: if an elected member voluntarily gives up their membership of a political party; if they vote or abstain from voting in the House contrary to any direction (whip) issued by their party; if an independently elected member joins any political party; or if a nominated member joins a party after six months of taking their seat. The authority to decide on questions of disqualification under Paragraph 6 rests with the Speaker or Chairman of the respective House.
The law has been significantly connected to the 91st Amendment Act of 2003, which tightened the provisions by deleting the exception that allowed for a split in a political party (where one-third of members defected) without disqualification. The only exception that remains is a merger, which is permitted only if at least two-thirds of the members of a legislative party agree to merge with another party. A crucial related concept is the landmark Supreme Court judgment in Kihoto Hollohan v. Zachillhu (1992), which upheld the constitutional validity of the 10th Schedule but ruled that the decision of the Speaker/Chairman is subject to judicial review on grounds like mala fides or perversity, striking down the provision in the original law that barred judicial scrutiny.