this point Mr. Justice White said, and his opinion coincided with that of the majority, that 'It is not necessary to trace the want of authority of the United States to impose a license exaction on the agents of the State to an express provision of the Constitution, since the court has constantly held that the absence of authority in the Government of the United States to tax or burden the agencies or instrumentalities of a state government, and the like want of authority on the part of the States to tax the agencies or instrumentalities of the National Government, results from the dual system of government which the Constitution created, and that the continuance in force of such a prohibition is absolutely essential to the preservation of both governments.' 1 But it is believed that the opinion of the minority and the judgement of the court safeguard the right of the State as a political unit and the exercise of its sovereign powers. Within that sphere the individual citizen may not enter, but when the State, leaving its preferred sphere, comes down to the plane of the citizen, doing what he does and competing with him in industry and commerce, there does not appear to be any compelling reason why the act of the State should be treated differently from the act of the individual, when each is the same. When the State elects to stand in the shoes of the citizen the foot may be pinched. As a State, and in the exercise of its functions as such, it is and should be exempt from taxation. As a man of affairs, and to the extent of its business transactions, it should be subjected to, not be above, the law; and it is in the interest of its people that this should be so. There is, however, a difference of opinion on this question, both at home and abroad, just as there is a difference of opinion whether a diplomat, everywhere entitled to immunity, loses that immunity if he goes into business and to the extent of the business. This the opinion of the majority would confirm; this the opinion of the minority would deny. It is believed that correct principle and sound doctrine are admirably combined and felicitously expressed by Mr. Chief Justice Marshall, who in delivering the opinion of the Supreme Court in Bank of the United States v. Planters' Bank of Georgia (9 Wheat. 904, 907) said as long ago as 1824: It is, we think, a sound principle, that when a government becomes a partner in any trading company, it divests itself, so far as concerns the transactions of that company, of its sovereign character, and takes that of a private citizen. Instead of communicating to the company its privileges and prerogatives, it descends to a level with those with whom it associates itself, and takes the character which belongs to its associates, and to the business which is to be transacted. 55. State of Missouri v. State of Illinois. The first case of Missouri v. Illinois (180 U.S. 208), turned upon two points, whether, admitting the facts stated in complainant's bill, the Supreme Court could take jurisdiction of the controversy, and, admitting the jurisdiction, whether the facts as pleaded constituted a cause of action. The court, it will be observed, in the opinion delivered by Mr. Justice Shiras, was very careful to confine itself to State of South Carolina v. United States (199 U.S. 437, 464–5). Dispute as to the facts. Existence of nui the question of jurisdiction and to the justiciable nature of the controversy, without expressing any opinion as to the facts, although a demurrer to an answer admits the truth of the facts properly pleaded, and the court would have been justified in so considering them as true. As, in controversies between individuals, the defendant is ordinarily allowed to answer if the demurrer is overruled, so and especially, in controversies between States, the defendant would be allowed to answer, notwithstanding the overruling of the demurrer. Counsel for Illinois availed themselves of the permission to file answers to the complaint of the State of Missouri after the demurrer they had interposed was not sustained by the court, and upon the facts made out by the pleadings, consisting of the complainant's bill and the defendant's answers, the second case of Missouri v. Illinois (200 U.S. 496) came before the Supreme Court and was decided by that body in 1906 in favour of the defendant, dismissing the bill without prejudice-that is to say, dismissing the bill upon the facts as then stated, and leaving the State of Missouri free to appear before the court at some subsequent time with evidence supporting its cause and justifying an injunction. It will perhaps aid the reader if, to the decision of the court, the summary of the case of Missouri, contained in the official report, be here prefixed: The substantial purpose of the complaint is to subject the construction and operation of the drainage channel from the Chicago River at Chicago, southwestwardly to the Desplaines River at Lockport, a point immediately above Joliet, to the court's supervision, upon the charge that the method of construction and operation creates and constitutes a continuing nuisance, dangerous to the health of the people of Missouri; and which if not restrained, results in the daily transportation, by artificial means, and through an unnatural channel, of large quantities of undefecated sewage, and of accumulated deposits in the harbor of Chicago, and in the bed of the Illinois River, which poison the water supply of the inhabitants of Missouri and injuriously affect that portion of the Mississippi River which lies within complainant's jurisdiction. No attack is made upon the canal or artificial channel as an unlawful structure, nor is any attempt made to prevent its use as a waterway. Complainant seeks relief against the pouring of undefecated and unpurified sewage and filth through it by the artificial arrangements into the Mississippi River to the detriment of complainant and its inhabitants.1 Such was the contention of the complainant. The contention of the defendant, as stated in the answer, and in the opinion of the court apparently substantiated by the proof presented, was thus summarized in the official report: The water of the Illinois River at Grafton since the opening of the drainage canal, as disclosed by chemical and bacterial surveys covering a long period of time, sance is, if anything, in a better sanitary condition since the opening of the drainage canal denied by than it was prior thereto. Illinois. The Illinois River at its mouth, from a sanitary standpoint, based upon chemical and bacterial analyses, is less polluted and less dangerous to health than is either the Missouri River or the Mississippi River, and the Illinois River, emptying into the Mississippi and Missouri Rivers, is contaminated and polluted by these two rivers, instead of contaminating and polluting the combined waters of the Mississippi and Missouri Rivers.2 After stating the facts as disclosed in the pleadings of plaintiff and defendant in the first case, and the overruling of the demurrer, Mr. Justice Holmes briefly touches State of Missouri v. State of Illinois (200 U.S. 496, 497). 2 Ibid. (200 U.S. 496, 510). upon the jurisdiction of the court decided in the previous case, and thus states it in Judgeterms interesting to the States of the Union and to the nations of the society of nations : ment of the Court in favour of Illi The decision upon the demurrer discussed mainly the jurisdiction of the court, nois. and, as leave to answer was given when the demurrer was overruled, naturally there was no very precise consideration of the principles of law to be applied if the plaintiff should prove its case. That was left to the future with the general intimation that the nuisance must be made out upon determinate and satisfactory evidence, that it must not be doubtful and that the danger must be shown to be real and immediate. The nuisance set forth in this bill was one which would be of international importance a visible change of a great river from a pure stream into a polluted and poisoned ditch. 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 rose between independent sovereignties, might lead to war. Whatever differences of opinion there might be upon matters of detail, the jurisdiction and authority of this court to deal with such a case as that is not open to doubt. But the evidence now is in, the actual facts have required for their establishment the most ingenious experiments, and for their interpretation the most subtle speculations of modern science, and therefore it becomes necessary at the present stage to consider somewhat more nicely than heretofore how the evidence is to be approached.1 The learned Justice next takes up three matters of importance in order to show: first, that the commission of an act which might prove to be a nuisance was not forbidden by the Constitution of the United States, and, in support of this proposition, cites the leading case of Pennsylvania v. Wheeling and Belmont Bridge Company (13 Howard, 518), discussed in the first case, and the case of Kansas v. Colorado (185 U.S. 125), with the facts and holding in which the reader is familiar; second, that the Congress of the United States could pass an act regulating the use of the waters of these navigable streams, inasmuch as the regulation of interstate commerce is, by the Constitution, vested in the Congress, and that in the present case Congress had not exercised the power with which it was vested; and third, that the State of Illinois had authorized the construction of the drainage system, and that, in the absence of a constitutional prohibition, or legislation of Congress, the act of the State of Illinois in its sovereign capacity was not subject to the supervision of the equally sovereign State of Missouri, and that the exercise of the right of each sovereign was to be determined by the principles of law applicable to such cases. The language of the court on each of these points is especially important, because of the international bearings of the case, and Mr. Justice Holmes had the advantage which his predecessor did not have, of delivering the unanimous opinion of his brethren. On the first point the learned Justice says: The first question to be answered was put in the well-known case of the Wheeling bridge. Pennsylvania v. Wheeling & Belmont Bridge Co., 13 How. 518. In that case, also, there was a bill brought by a State to restrain a public nuisance, the erection of a bridge alleged to obstruct navigation, and a supplemental bill to abate it after it was erected. The question was put most explicitly by the dissenting judges, but it was accepted by all as fundamental. The Chief Justice observed that if the bridge was a nuisance it was an offense against the sovereignty whose law had been violated, and he asks what sovereignty that was. 13 How. 581; Daniel, J., 13 How. 599. See also Kansas v. Colorado, 185 U.S. 125. It could not be Virginia, because that 1 State of Missouri v. State of Illinois (200 U.S. 496, 517-18). No sovereignty is here violated. the matter, State had purported to authorize it by statute. The Chief Justice found no prohibition by the United States. 13 How. 580. No third source of law was suggested by any one. The majority accepted the Chief Justice's postulate, and found an answer in what Congress had done.1 As to the second point, the learned Justice thus speaks: Congress It hardly was disputed that Congress could deal with the matter under its power could to regulate commerce. The majority observed that although Congress had not regulate declared in terms that a State should not obstruct the navigation of the Ohio, by bridges, yet it had regulated navigation upon that river in various ways and had sanctioned the compact between Virginia and Kentucky when Kentucky was let into the Union. By that compact the use and navigation of the Ohio River, so far as the territory of either State lay thereon, was to be free and common to the citizens of the United States. The compact, by the sanction of Congress, had become a law of the Union. A State law, which violated it was unconstitutional. Obstructing the navigation of the river was said to violate it, and it was added that more was not necessary to give a civil remedy for an injury done by the obstruction. 13 How. 565. 566. At a later stage of the case, after Congress had authorized the bridge, it was stated again in so many words that the ground of the former decision was that 'the act of the Legislature of Virginia afforded no authority or justification. It was in conflict with the acts of Congress, which were the paramount law'. 18 How. 421, 430.2 On the third point, and directly touching the case in hand, the learned Justice states: but has bidden the act of Illinois. In the case at bar, whether Congress could act or not, there is no suggestion that not for it has forbidden the action of Illinois. The only ground on which the State's conduct can be called in question is one which may be implied from the words of the Constitution. The Constitution extends the judicial power of the United States to controversies between two or more States and between a State and citizens of another State, and gives this court original jurisdiction in cases in which a State shall be a party. Therefore, if one State raises a controversy with another, this court must determine whether there is any principle of law, and, if any, what, on which the plaintiff can recover. But the fact that this court must decide does not mean, of course, that it takes the place of a legislature. Some principles it must have power to declare. For instance, when a dispute arises about boundaries, this court must determine the line, and in doing so must be governed by the rules explicitly or implicitly recognized. Rhode Island v. Massachusetts, 12 Pet. 657, 737. It must follow and apply those rules, even if legislation of one or both of the States seems to stand in the way. The words of the Constitution would be a narrow ground, upon which to construct and apply to the relations between States the same system of municipal law in all its details which would be applied between individuals. If we suppose a case which did not fall within the power of Congress to regulate, the result of a declaration of rights by this court would be the establishment of a rule which would be irrevocable by any power except that of this court to reverse its own decision, an amendment of the Constitution, or possibly an agreement between the States sanctioned by the legislature of the United States.3 In view of the express decision of the court in the first case of Missouri v. Illinois, and the language used by Mr. Justice Shiras on behalf of the majority of his brethren, it may seem that the facts stated by Mr. Justice Holmes were unnecessary, inasmuch as he was scattering grain, as it were, upon a field already sown. He himself was aware of this, but the international aspect of the case appealed very strongly to him 1 State of Missouri v. State of Illinois (200 U.S. 496, 518). a Ibid. (200 U.S. 496, 519-20). as a justification for going over ground already covered; and he had in mind the case of Kansas v. Colorado (185 U.S. 125), in which the international element was uppermost, and which was considered and decided by the court in the interval between the two cases of Missouri v. Illinois. The learned Justice thus met the objection, if any, which his brethren did not make, for the court was unanimous and thus obviates criticism on the part of the reader that he is familiar with the principles just laid down by the learned Justice: The purpose of the foregoing observations is not to lay a foundation for departing from that decision, but simply to illustrate the great and serious caution with which it is necessary to approach the question whether a case is proved. It may be imagined that a nuisance might be created by a State upon a navigable river like the Danube, which would amount to a casus belli for a State lower down, unless removed. If such a nuisance were created by a State upon the Mississippi the controversy would be resolved by the more peaceful means of a suit in this court. But it does not follow that every matter which would warrant a resort to equity by one citizen against another in the same jurisdiction equally would warrant an interference by this court The with the action of the State. It hardly can be that we should be justified in declaring Court will statutes ordaining such action void in every instance where the Circuit Court might if the intervene in a private suit, upon no other ground than analogy to some selected system nuisance of municipal law, and the fact that we have jurisdiction over controversies between is clearly States. . . . proved. Before this court ought to intervene the case should be of serious magnitude, clearly and fully proved, and the principle to be applied should be one which the court is prepared deliberately to maintain against all considerations on the other side. See Kansas v. Colorado, 185 U.S. 125.1 As an illustration of the caution to be observed in cases of this kind, the learned It is a question of the first magnitude whether the destiny of the great rivers is to be the sewers of the cities along their banks or to be protected against everything which threatens their purity.2 And after calling attention to the fact that the practice of discharging refuse into the river is general, including that of Missouri, he reaches the conclusion that such action of the States is permissible and is only to be forbidden when the act is an abuse of a general practice. The line is to be drawn, to be sure, but it must be clear that the evil complained of was produced by the defendant State and that the complainant, by its discharges in the river above the point where the Illinois flows into the Mississippi has not contributed to the evil. The question thereupon becomes one of fact, for if the Mississippi from the juncture of the Illinois is not polluted, and its waters continue, as before, to flow in their accustomed purity or impurity, the case of Missouri falls of its own weight. The difficulty before the court was very great in this part of the case, for it had to weigh and to strike a balance between the evidence of the plaintiff, tending to show a nuisance, and the evidence of the defendant, tending to negative it—a task for experts in sanitation rather than for experts in jurisprudence. But the court bent itself to the task, Mr. Justice Holmes stating on its behalf : We have studied the plaintiff's statement of the facts in detail, and have perused the evidence, but it is unnecessary for the purposes of the decision to do more than 1 State of Missouri v. State of Illinois (200 U.S. 496, 520—1). Ibid. (200 U.S. 496, 521). only act |