Yes — a person may leave one party and join another. But once someone has been elected on a particular party's ticket, leaving that party is called defection, and the law then attaches consequences to it.
The chapter defines defection as abandoning or switching from the party under whose banner the candidate was elected. It includes joining another party, and also "choosing to act independently of the party's decisions, particularly in matters such as voting in the legislature."
The chapter deliberately gives you both readings of the same act:
| Read through party discipline and stability | Read through conscience and public expectations |
|---|---|
| The voter chose the candidate partly because of the party's programme. Switching afterwards changes what the voter bought without asking them, so it is seen as political opportunism, and repeated switching can bring down governments and make policy unstable. | A member may come to believe the party is wrong, or that opinion in the constituency has moved. On this reading, obeying one's conscience or responding to changing public expectations is a legitimate part of representing people rather than a betrayal. |
What the law does. The Anti-Defection Law was passed in 1985 through the 52nd Constitutional Amendment Act, to prevent defection and give the elected government stability. Under it, a member of Parliament or of a State Assembly who voluntarily gives up party membership, or votes against the party's instructions (whip), can be disqualified from the House. The Speaker or Chairman of the House decides such cases.