The locus standi rule to move the court was liberalized by the case

The locus standi rule to move the court was liberalized by the case of:

S.R. Bommai v. Union of India
Minerva Mills v. Union of India
S.P. Gupta v. Union of India
Kesavananda Bharati v. State of Kerala
This question was previously asked in
UPSC CAPF – 2015
The locus standi rule, which requires a party to have a direct and substantial interest in the outcome of a case to be able to file a suit, was significantly liberalized in India by the Supreme Court in the case of S.P. Gupta v. Union of India (1981), also known as the Judges’ Transfer case.
This case is considered a landmark in the development of Public Interest Litigation (PIL) in India, allowing any person acting bona fide and having sufficient interest to approach the court for judicial redress in cases where legal injury is caused to a person or class of persons who, by reason of their poverty, disability, or socially or economically disadvantaged position, cannot approach the court for relief.
Other mentioned cases are also significant: S.R. Bommai case (1994) related to Article 356 (President’s Rule); Minerva Mills case (1980) related to the basic structure doctrine and validity of constitutional amendments; Kesavananda Bharati case (1973) established the basic structure doctrine of the Constitution.