Wetlands provide a range of ecosystem services related to water quality, flood control, aquifer recharge, shoreline stabilization and species habitats. A broader lesson is that environmental law, to be effective, must take science into account. … Sadly, the US Supreme Court’s recent ruling in Sackett v. Environmental Protection Agency demonstrates that a majority of the justices never learnt that lesson. The case has eviscerated federal protection of wetlands under the Clean Water Act, the principal federal law responsible for the improvement of the country’s water quality over the past 50 years.