The chief instrument through which judicial activism has flourished in India is public interest litigation (PIL) or social action litigation (SAL). It refers to litigation undertaken to secure public interest and demonstrates the availability of justice to socially-disadvantaged parties and was introduced by Justice P. N. Bhagwati. It is a relaxation on the traditional rule of locus standi. Before 1980s the judiciary and the Supreme Court of India entertained litigation only from parties affected directly or indirectly by the defendant. It heard and decided cases only under its original and appellate jurisdictions. However, the Supreme Court began permitting cases on the grounds of public interest litigation, which means that even people who are not directly involved in the case may bring matters of public interest to the court. It is the court's privilege to entertain the application for the PIL. History One of the earliest public interest litigation was filed by G. Vasantha Pai who filed a case in the Madras High Court against the then sitting Chief Justice of the Madras High court S. Ramachandra Iyer after it was found the judge had forged his date of birth to avoid compulsory retirement at the age of 60 and his younger brother sent invitations to celebrate his 60th birthday and Pai found evidence after photographing his original birth register which showed his real age. Ramachandra Iyer resigned on a request from the then Chief Justice of India P. B. Gajendragadkar as the case would damage the judiciary and he had resigned before the case came up for hearing this led the case to be dismissed as he had resigned. In December 1979, Kapila Hingorani filed a petition in regards to the condition of the prisoners detained in the Bihar jail, whose suits were pending in court. The petition was signed by prisoners of the Bihar jail and the case was filed in the Supreme Court of India before the bench headed by Justice P. N. Bhagwati. The petition was filed under the name of a prisoner, Hussainara Khatoon, and the case was therefore named Hussainara Khatoon Vs State of Bihar. The Supreme Court decided that prisoners should receive free legal aid and fast hearings. As a result, 40,000 prisoners were released from jail. Thereafter many similar cases have been registered in the Supreme Court. It was in the case of SP Gupta vs Union of India that the Supreme Court