Precautionary principle
A principle allowing or requiring preventive action where serious or irreversible environmental harm is plausible despite scientific uncertainty.
The precautionary principle shifts environmental law from reacting to proven damage toward preventing credible risks before full scientific certainty exists. It may justify monitoring, restrictions, authorization conditions, burden-of-proof rules or phased approvals for activities with potentially serious impacts. Swiss environmental law strongly reflects precaution, particularly through emission limitation and preventive planning. The principle must still be applied proportionately, with attention to evidence, alternatives, economic reasonableness and fundamental rights. International and EU law use similar concepts, though legal force and thresholds vary.