Kesavananda Bharati v. State of Kerala is a seminal case on constitutional law that established the 'basic structure doctrine,' limiting Parliament's power to amend the Constitution. While it was brought by an individual whose property rights were affected, its scope was a fundamental constitutional challenge, predating the modern concept of PIL which evolved in the late 1970s. The other cases are classic examples of PIL: Vineet Narain (Hawala scam, CBI independence), ADR (electoral reforms), and Vincent Panikurlangara (banning harmful drugs, public health).