In the Constitutional Convention the necessity for some tribunal to preserve peace and harmony between the States was fully conceded by all, but the form of court was the subject of some discussion. One proposal was that the Senate should be a court to decide between the States all questions disturbing peace and harmony between the States, while the Supreme Court was given only jurisdiction in controversies over boundaries. Ultimately, however, the judicial power of the United States exercised through the Supreme Court was extended to “controversies between States,” without exception. To those who do not closely look into this jurisdiction of the Supreme Court it seems no different from that of the ordinary municipal court over controversies between individuals. The States are regarded merely as municipal or private corporations subject to suit process, trial, and judgment to be rendered on principles of municipal law declared by statute of State Legislature or Congress, or established as the common law. It is assumed that the Constitution has destroyed the independence and sovereignty of the States and made the arrangement a mere domestic affair. This is a misconception. The analogy between the function of the Supreme Court in hearing and deciding controversies between States and that of an international tribunal sitting to decide a cause between sovereign nations is very close. When the suit by one State against another presents a case that is controlled by provisions of the Federal Constitution, of course there is nothing international about it. But most controversies between States are not covered by the Federal Constitution. That instrument does not, for instance, fix the boundary line between two States. It does not fix the correlative rights of two States in the water of a non-navigable stream that flows from one of the States into another. It does not regulate the use which the State up stream may make of the water, either by diverting it for irrigation or by using it as a carrier of noxious sewage. Nor has Congress any power under the Constitution to lay down principles by Federal law to govern such cases. The Legislature of neither State can pass laws to regulate the right of the other State. In other words there is nothing but international law to govern. There is no domestic law to settle this class of cases any more than there would be if a similar controversy were to arise between Canada and the United States.