City of Milwaukee v. Illinois

Nine years ago, in Illinois v. Milwaukee, 406 U. S. 91 (1972), this Court unanimously determined that Illinois could bring a federal common-law action against the city of *333Milwaukee, three other Wisconsin cities, and two sewerage commissions. At that time, Illinois alleged that the discharge of raw and untreated sewage by these Wisconsin entities into Lake Michigan created a public nuisance for the citizens of Illinois. The Court remitted the parties to an appropriate federal district court, “whose powers are adequate to resolve the issues.” Id., at 108.

Illinois promptly initiated the present…