India's anti-defection law lives in the Tenth Schedule of the Constitution. It is a short text doing very heavy work: deciding when a sitting legislator forfeits their seat because of how they have voted, or which side of the aisle they have walked to.
1. Origin: the 52nd Amendment, 1985
The Tenth Schedule was inserted into the Constitution by the Constitution (Fifty-second Amendment) Act, 1985. The political context is familiar: through the 1960s and 1970s, governments at the Centre and in the States were repeatedly destabilised by floor-crossings, often coordinated and openly transactional. Parliament chose to constitutionalise a response.
The Schedule applies to members of both Houses of Parliament and the State Legislatures. Its central question is straightforward: when does a legislator's conduct amount to defection, and what follows?
2. The grounds for disqualification
Read functionally, the Schedule identifies two principal grounds on which a member of a House may be disqualified:
- Voluntarily giving up membership of the political party on whose ticket the member was elected. The phrase has been read broadly by the Supreme Court to include conduct, not just formal resignation.
- Voting or abstaining contrary to a direction (a "whip") issued by the party, without prior permission and without subsequent condonation within fifteen days.
Independents who join a political party after election, and nominated members who join one after the relevant six-month window, are likewise within the Schedule's reach.
The Tenth Schedule asks one constitutional question of every legislator: did you remain, in substance, the person the electorate sent to the House?
3. The Speaker's role — and its limits
Disqualification questions under the Tenth Schedule are decided not by a court at first instance but by the presiding officer of the House — the Speaker of the Lok Sabha or a State Assembly, or the Chairman of the Rajya Sabha or a State Council. That choice of forum has been the most contested feature of the law.
In Kihoto Hollohan v. Zachillhu (1992), the Supreme Court upheld the constitutional validity of the Schedule but read down the finality clause: the Speaker's order is subject to judicial review on limited grounds, including mala fides, perversity, and violation of natural justice. Later decisions, including Keisham Meghachandra Singh (2020), have pressed the Speakers to decide references within a reasonable time, treating prolonged delay as itself reviewable.
4. The split and the merger
The original Schedule recognised a "split" — a defence available when a significant block of legislators in a party left together. The Ninety-first Amendment (2003) deleted that defence. What survives is the narrower "merger" route in paragraph 4: a member is protected from disqualification only where two-thirds of the legislative party agree to merge with another political party.
5. What the law leaves open
Several questions continue to invite litigation and academic comment:
- What counts as "voluntarily giving up" party membership when the act is one of speech or association rather than a formal resignation?
- How long may a presiding officer take to decide a disqualification petition, and what is the remedy when delay distorts the political consequence?
- Should the adjudicatory function be moved away from the Speaker — to a tribunal or to the Election Commission — to address concerns about partisanship?
6. Where the volumes go further
The two-volume reference treats each of these threads with the case law and parliamentary practice that any practitioner needs in front of them. For a public-facing overview, PRS Legislative Research maintains a useful explainer; for the deeper apparatus, the book is the natural next step.