M.C. Mehta v. Union of India (2004)12 SCC 118

Court explained the scope of "precautionary principle" observing that it requires anticipatory action to be taken to prevent harm. The harm can be prevented even on a reasonable suspicion. It is not always necessary that there should be direct evidence of harm to the environment. The concept of "sustainable development" has been explained that it covers the development that meets the needs of the person without compromising the ability of the future generation to meet their own needs. It means the development, that can take place and which can be sustained by nature/ecology with or without mitigation. In such eventuality, a balance has to be struck, for the reason that if the activity is allowed to go, there may be irreparable damage to the environment and there may be irreparable damage to the economic interest.