On 28 August 1996, a three-judge Bench led by Justice Kuldip Singh held that 'sustainable development', the 'precautionary principle' and the 'polluter pays' principle are part of the law of the land — and ordered the discharge of pollution fees by tanneries in Tamil Nadu that had contaminated the River Palar and rendered 35,000 hectares of agricultural land unfit for cultivation. The judgment, together with *M.C. Mehta (Oleum Gas Leak)*, supplies the foundational architecture of Indian environmental law. A digest of the doctrines, the directions, and what they require.