The U.S. Supreme Court case Wisconsin et al. v. Illinois et al., 1932, revolved around a dispute over water diversion from Lake Michigan by the state of Illinois for its Sanitary and Ship Canal project. The states of Wisconsin, Michigan, New York and Pennsylvania argued that this diversion lowered lake levels significantly affecting their commercial interests and violating their rights to equitable use of the Great Lakes' waters under common law doctrine. They sought an injunction against further diversions by Illinois. Illinois countered that it had Congressional approval for its actions via a series of legislative acts dating back to 1889 which allowed them to divert up to 10,000 cubic feet per second (cfs) from Lake Michigan. The court ruled in favor of Illinois stating that while there was evidence showing some harm caused by the diversion, it wasn't significant enough to warrant an injunction or overturning previous congressional approvals given to Illinois regarding water usage.

In the dissenting opinion for Wisconsin et al. v. Illinois et al., it was argued that the Supreme Court should not have jurisdiction over this case, as it is essentially a political issue rather than a legal one. The dissenting justices believed that disputes between states about water rights and usage are matters best left to Congress or other legislative bodies, not the courts. They also expressed concern about setting a precedent where any state could bring another state to court over similar issues of resource allocation and environmental impact, potentially leading to an unmanageable number of cases before the Supreme Court. Furthermore, they disagreed with majority's conclusion on merits of case; they did not believe there was sufficient evidence proving Illinois' actions were causing significant harm to Wisconsin's water supply or environment.