The U.S. Supreme Court case Illinois v. City of Milwaukee, Wisconsin et al., 1971, revolved around the issue of water pollution in Lake Michigan. The state of Illinois filed a lawsuit against the city of Milwaukee and other defendants for allegedly discharging sewage into Lake Michigan which was causing significant environmental damage and posed health risks to residents living near or using the lake's waters in Illinois. The key question before the court was whether it had original jurisdiction over such interstate disputes under Article III Section 2 Clause 2 of the Constitution (which grants original jurisdiction to cases involving states as parties). In a unanimous decision, Justice William O Douglas delivered an opinion stating that federal common law does apply in matters pertaining to air and water disputes between states because they are considered public rights issues rather than private rights issues; hence, giving rise to federal questions that can be adjudicated by Federal Courts including Supreme Court under its original jurisdiction.

In the dissenting opinion for Illinois v. City of Milwaukee, Wisconsin et al., Justice Douglas argued that federal common law should not be applied to this case as it would undermine state sovereignty and interfere with their ability to manage their own resources. He contended that the majority's decision was an overreach of federal power into areas traditionally controlled by states, such as water pollution control. Furthermore, he expressed concern about the potential implications of allowing a single judge or court to dictate standards for interstate environmental issues without clear congressional authorization or guidance from expert administrative agencies like EPA. Instead, he believed these disputes should be resolved through cooperative efforts between states under existing statutory frameworks rather than judicial intervention based on uncertain legal principles.