P sought to restrain the discharge of the sewage of Chicago through an artificial channel into the Desplaines river. That river empties into the Illinois river, and the latter empties into the Mississippi at a point about 43 miles above the city of St. Louis. It was alleged that the discharge would send 1,500 tons of poisonous filth daily into the Mississippi. It was alleged that the defendant sanitary district was acting in pursuance of a statute of the state of Illinois and as an agency of that state. On a demurrer to the motion for leave to file a bill of complaint, D argued that the Sanitary District was the proper defendant and that D should not have been made a party. That argument was rejected. A supplemental bill alleges that since the filing of the original bill the drainage canal has been opened and put into operation, and has produced and is producing sewage. D alleges that the new plan sends the water of the Illinois river into the Mississippi much purer than it was before, that many towns and cities along the Missouri and Mississippi discharge their sewage into those rivers, and that if there is any trouble P must look nearer home for the cause. The only question presented was whether, as between the states of the Union, this court was competent to deal with a situation which, if it arose between independent sovereignties, might lead to war.