Splits and mergers and anti-defection law
Splits, mergers and alliances have frequently disrupted the compositions of political parties. This has led to a number of disputes over which section of a divided party gets to keep the party symbol, and how to classify the resulting parties in terms of national and state parties. The Election Commission has to resolve these disputes, although its decisions can be challenged in the courts.
Election Petitions
Any elector or candidate can file an election petition if he or she thinks there has been malpractice during the election. An election petition is not an ordinary civil suit, but treated as a contest in which the whole constituency is involved. Election petitions are tried by the High Court of the State involved, and if upheld can even lead to the re-staging of the election in that constituency.
Reference:
Election Commission of India, http://eci.nic.in/.