The control of international relations being exclusively vested in the Federal Government, it necessarily follows that the several States have no authority to enter into any diplomatic or .political relations with foreign powers.1 Nevertheless, from an excess of caution, the federal Constitution declares that, "No State shall enter into any treaty, alliance or confederation," and that, "No State shall, without the consent of Congress, . . . enter into any agreement or compact with another State, or with a foreign power."
It will be noticed that in the latter of these two constitutional clauses, the qualification "without the consent of Congress " is introduced. There has, therefore, never been any doubt, but that, when this congressional consent is given, the several States of the American Union may enter into agreements and compacts with one another, so long as their effect is not to create what in political language is termed an "alliance " or "Confederation." 2 Not only this; it has been held that there are a variety of subjects concerning which the several States may enter into agreements with one another without the necessity of obtaining the consent of Congress. Upon this point, in Virginia v. Tennessee,3 the Supreme Court say: "There are many matters upon which different States may agree that can in no respect concern the United States. If, for instance, Virginia should come into possession and ownership of a small parcel of land in New York which the latter State might desire to acquire as a site for a public building, it would hardly be deemed essential for the latter State to obtain the consent of Congress before it could make a valid agreement with Virginia for the purchase of the land. If Massachusetts, in forwarding its exhibits to the World's Fair at Chicago, should desire to transport them a part of the distance over the Erie Canal, it would hardly be deemed essential for that .State to obtain the consent of Congress before it could contract with New York for the transportation of the exhibits through the State in that way. If the bordering line of the two States should cross some malarious and disease-producing district, there could be no possible reason, on any conceivable public grounds, to obtain the consent of Congress for the bordering States to agree to unite in removing the cause of the disease. So, in the case of threatened invasion of cholera, plague, or other causes of sickness and death, it would be the height of absurdity to hold that the threatened States could not unite in providing means to prevent and repel the invasion of the pestilence without obtaining the consent of Congress, which might not be at the time in session."
1 See chapter XXXII (Foreign Relations: The Treaty Power).
2 Green v. Biddle, 8 Wh. 1; 5 L, ed. 547; Poole v. Fleeger, 11 Pet. 185; 9 L. ed. 680.
3 148 U. S. 503; 13 Sup. Ct. Rep. 728; 37 L. ed. 537.
"If, then," the court asks, "the terms 'compact' or 'agreement' in the Constitution do not apply to every possible compact or agreement between one State and another, for the validity of which the consent of Congress must be obtained, to what compacts or agreements does the Constitution apply?" " Looking at the clause in which the terms 'compact' or 'agreement' appear," answers the court, "it is evident that the prohibition is directed to the formation of any combination tending to the increase of political power in the States, which may encroach upon or interfere with the just supremacy of the United States." 4
The court continue: " Compacts or agreements - and we do not perceive any difference in the meaning, except that the word 'compact' is generally used with reference to more formal and serious engagements than is usually implied in the term 'agreement' - cover all stipulations affecting the conduct or claims of the parties. The mere selection of parties to run and designate the boundary line between two States, or to designate what line should be run, of itself imports no agreement to accept the line run by them, and such action of itself does not come within the prohibition. Nor does legislative declaration, following such line, that it is correct, and shall thereafter be deemed the true and established line, import by itself a contract or agreement with the adjoining State. It is a legislative declaration which the State and individuals affected by the recognized boundary line may invoke against the State as an admission, but not as a com-pact or agreement. The legislative declaration will take the form of an agreement or compact when it recites some consideration for it from the other party affected by it, for example, as made upon a similar declaration of the border or contracting State. The mutual agreements may then be reasonably treated as made upon mutual considerations. The compact or agreement will then be within the prohibition of the Constitution or without it. according as the establishment of the boundary line may lead or not to the increase of the political power or influence of the States affected, and thus encroach or not upon the full and free exercise of federal authority. If the boundary estab-lished is so run as to cut off an important and valuable portion of a State, the political power of the State enlarged would be affected by the settlement of the boundary; and to an agreement for the running of such a boundary or rather for its adoption afterward, the consent of Congress may well be required. But the running of a boundary may have no effect upon the political influence of either State, it may simply serve to mark and define that which actually existed before, but was undefined and unmarked. In that case the agreement for the running of the line, or its actual survey, would in no respect displace the relation of either of the States to the General Government. There was, therefore, no compact or agreement between the States in this case which required, for its validity, the consent of Congress, within the meaning of the Constitution, until they had passed upon the report of the commissioners, ratified their action, an 1 mutually declared the boundary established bv them to be the true and real boundary between the States. Such ratification was mutually made by each State in consideration of the ratification of the other." 5
4 The court go on to quote with approval from Story's Commentaries upon the Constitution, Sec. 1403.