Precautionary Principle

The precautionary principle requires action to prevent environmental harm even when scientific knowledge about the risk is incomplete. Where there are threats of serious or irreversible damage, lack of full scientific certainty cannot justify postponing proportionate and cost-effective preventive measures.

What the principle requires

Decision-makers must address credible environmental risks before damage occurs, rather than waiting for conclusive proof or attempting repair afterward.

• Authorities must anticipate, prevent and attack the causes of environmental degradation.
• A project must be appraised using available scientific evidence, including the nature, magnitude and reversibility of possible harm.
• Safeguards may include alternatives, mitigation, monitoring, restrictions or refusal of permission where risks remain unacceptable.
• The response should be proportionate to the possible harm; precaution does not mean that every uncertain activity must automatically be prohibited.

Burden under environmental decision-making

In Vellore Citizens Welfare Forum v. Union of India, 1996, the Supreme Court treated the principle as an essential feature of sustainable development and part of Indian environmental law.

• The Court stated that scientific uncertainty should not postpone measures for preventing environmental degradation.
• The onus of proof may fall on the developer or industrial actor to show that the proposed activity is environmentally benign.
• The principle therefore supports prior environmental appraisal and informed scrutiny rather than approval first and assessment after damage.

Constitutional and regulatory relevance

The principle is read with the right to life under Article 21, the State's environmental duty under Article 48A, and the citizen's duty under Article 51A(g).

• Environmental impact assessment operationalises precaution by examining likely impacts before specified projects receive environmental clearance.
• The Environment (Protection) Act, 1986 provides the broad statutory framework under which environmental clearance requirements are issued.

How UPSC asks this