After decades of putting its constituents through permitting purgatory, San Francisco took the other side and won. In doing so, it avoided billions of dollars in fines from the Environmental Protection Agency because the Supreme Court held on March 4 that the Clean Water Act did not give the agency the power to punish the city for accidental discharges of pollutants after it complied with previously issued permits.

Passed in 1972, the Clean Water Act superseded the Federal Water Pollution Control Act of 1948, which had empowered the attorney general to collect civil damages in federal court from polluters who created a “public nuisance” in interstate waters. This system proved ineffective as there was always more than one polluter of any body of water, and it was difficult for courts to determine who was responsible for what percentage of the pollution in any case.