In the late 1960s and 70s, defections (elected legislators changing parties after the election) in Parliament and State Legislatures became very frequent, so frequent in fact, that the epithet "Aaya Ram Gaya Ram" was coined to describe the same.  To curb this problem which created instability in our legislatures, Parliament amended the Constitution.  They inserted the Tenth Schedule to the Constitution "to curb the evil of political defections".  As a result, we currently have an anti-defection law with the following features: 1.  If an MP/MLA who belongs to a political party voluntarily resigns from his party or, disobeys the party "whip" (a direction given by the party to all MPs/ MLAs to vote in a certain manner), he is disqualified.   The party may however condone the MP/ MLA within 15 days. 2.  An independent MP/ MLA cannot join a political party after the election. 3.  An MP/ MLA who is nominated (to the Rajya Sabha or upper houses in state legislatures) can only join a party within 6 months of his election. 4.  Mergers of well-defined groups of individuals or political parties are exempted from disqualification if certain conditions are met. 5.  The decision to disqualify is taken by the Speaker/ Chairman of the House. The table below summarizes provisions of anti-defection law in some other countries.  (For more, click here).  As one may note, a number of developed countries do not have any law to regulate defection.

Regulation of defection in some countries

Country Experi-ence Law on defection The Law on Defection
Bangladesh Yes Yes The Constitution says a member shall vacate his seat if he resigns from or votes against the directions given by his party.  The dispute is referred by the Speaker to the Election Commission.
Kenya Yes Yes The Constitution states that a member who resigns from his party has to vacate his seat.  The decision is by the Speaker, and the member may appeal to the High Court.
Singapore Yes Yes Constitution says a member must vacate his seat if he resigns, or is expelled from his party.  Article 48 states that Parliament decides on any question relating to the disqualification of a member.
South Africa Yes Yes The Constitution provides that a member loses membership of the Parliament if he ceases to be a member of the party that nominated him.
Australia Yes No  
Canada Yes No  
France Yes No  
Germany Yes No  
Malaysia Yes No  
United Kingdom Yes No  

We wrote an FAQ on Parliamentary Privilege for IBN Live. See http://ibnlive.in.com/news/what-puri-bedi-are-guilty-of-parl-privilege-faqs/179977-37.html The full text is reproduced below. Several MPs have given breach of privilege notices against actor Om Puri and ex-policewoman Kiran Bedi for using "derogatory and defamatory" language against Members of Parliament. In light of this, we explain the concept of breach of privilege and contempt of Parliament. What is parliamentary privilege? Parliamentary privilege refers to rights and immunities enjoyed by Parliament as an institution and MPs in their individual capacity, without which they cannot discharge their functions as entrusted upon them by the Constitution. Are these parliamentary privileges defined under law? According to the Constitution, the powers, privileges and immunities of Parliament and MP's are to be defined by Parliament. No law has so far been enacted in this respect. In the absence of any such law, it continues to be governed by British Parliamentary conventions. What is breach of privilege? A breach of privilege is a violation of any of the privileges of MPs/Parliament. Among other things, any action 'casting reflections' on MPs, parliament or its committees; could be considered breach of privilege. This may include publishing of news items, editorials or statements made in newspaper/magazine/TV interviews or in public speeches. Have there been earlier cases of breach of privilege? There have been several such cases. In 1967, two people were held to be in contempt of Rajya Sabha, for having thrown leaflets from the visitors' gallery. In 1983, one person was held in breach for shouting slogans and throwing chappals from the visitors' gallery. What is the punishment in case of breach of privilege or contempt of the House? The house can ensure attendance of the offending person. The person can be given a warning and let go or be sent to prison as the case may be. In the case of throwing leaflets and chappal, the offending individuals were sentenced to simple imprisonment. In the 2007 case of breach of privilege against Ambassador Ronen Sen, the Lok Sabha Committee on privileges held that the phrase "headless chicken" was not used by Shri Sen in respect of MPs or politicians. No action was taken against him. In 2008, an editor of an Urdu weekly referred to the deputy chairman of Rajya Sabha as a "coward" attributing motives to a decision taken by him. The privileges committee held the editor guilty of breach of privilege. The committee instead of recommending punishment stated that, “it would be better if the House saves its own dignity by not giving undue importance to such irresponsible articles published with the sole intention of gaining cheap publicity.”