Under The Representation of the People Act, 1951 (RPA), disputes arising out of the election of a Member of Parliament or a State Legislature are exclusively resolved through a structured judicial process, ensuring the integrity of India's democratic system.

Procedures to Decide Disputes:
The primary mechanism for challenging an election is an Election Petition. This petition must be filed by an elector or a candidate within 45 days from the date of election of the returned candidate. Critically, these petitions are filed directly in the High Court of the state within whose jurisdiction the election took place. The High Court holds original jurisdiction over such matters, ensuring a high level of judicial scrutiny. The proceedings are conducted akin to a civil suit, involving evidence, arguments, and witness examinations.

Grounds for Voiding an Election:
An election can be declared void on several explicit grounds enumerated in the RPA, including:

1. Corrupt Practices: As defined under Section 123 of the Act, these encompass activities like bribery, undue influence, appeal to religious/caste symbols, publishing false statements, or exceeding election expenditure limits.

2. Improper Acceptance/Rejection of Nomination: If a nomination paper was improperly accepted or rejected, and such improper decision materially affected the election outcome.

3. Disqualification of Candidate: If the returned candidate was disqualified under the Constitution or the RPA itself at the time of election.

4. Non-compliance with the Act/Rules: If there was any non-compliance with the provisions of the Constitution or the RPA that materially affected the result of the election.

5. Illegal Votes: If a substantial number of illegal votes were polled in favour of the returned candidate or legal votes were illegally rejected.

Remedy to Aggrieved Party:
If an aggrieved party is dissatisfied with the High Court's decision on an election petition, the ultimate remedy available is to file an appeal directly to the Supreme Court of India. This ensures a final judicial pronouncement by the apex court, providing the highest level of judicial oversight.

Relevant Case Laws:
The landmark case of Indira Nehru Gandhi v. Raj Narain (1975) is a classic example. The Allahabad High Court, applying the RPA, found the then Prime Minister Indira Gandhi guilty of corrupt practices (using government machinery for election purposes) and declared her election void. While the Supreme Court later provided a conditional stay, this case profoundly underscored the judiciary's power under the RPA to scrutinize and nullify elections on statutory grounds, reinforcing the rule of law in electoral democracy.