278 U.S. 367 (1929)
Wisconsin v. Illinois was a landmark case addressing interstate environmental disputes and the authority of the U.S.
Can one state unilaterally divert water from an interstate body, thereby potentially harming other states, without federal consent?
The Supreme Court has the equitable power to apportion natural resources across states in disputes over shared resources such as water bodies.
The Supreme Court held that Illinois could not lawfully appropriate the waters of Lake Michigan to the exclusion of the interest of other states. The Court determined that federal jurisdiction was necessary to balance these competing interstate interests.
For law students, Wisconsin v. Illinois is significant not only as a study of interstate dispute resolution but also as an exemplar of the Court’s role in managing conflicts involving shared natural resources. It highlights how federal intervention may be necessary when states' actions have adverse interstate impacts, which is vital in learning about state sovereignty, federalism, and environmental policy. This case serves as a cornerstone for understanding how natural resources falling across state borders are judicially regulated.