When courts hear a case where the case was filed not by the aggrieved persons but by others on their behalf and the case involves issue of public interest is called Public Interest Litigation or PIL.

1. PIL has become the most important vehicle of judicial activism.

2. Since the cases or issues of poor who do not have money to approach courts, could be appealed by anyone and could be heard in courts, made judiciary popular among the masses.

3. Clean air, unpolluted water, decent living etc. are rights for the entire society, and every man has the right to these. Whenever such rights are violated PIL are appealed by social workers or any spirited citizen on behalf of the aggrieved.