The document discusses several important public interest litigations (PILs) in India related to environmental protection. It summarizes key PIL cases that have established important legal precedents, including the first PIL filed in 1983 to stop limestone quarrying (Dehradun case), cases that reduced pollution in the Ganga River by industries (Ganga Water Pollution cases), and other cases related to industrial pollution, vehicular emissions, and more. The document also discusses prominent Indian environmental lawyer M.C. Mehta and his role in bringing many landmark PILs on environmental issues.