On September 3, 1940, President Franklin D. Roosevelt sent to Congress a message in which he stated, in part:

The crisis of practical international law has forced the science of international law to take stock of its most fundamental notions. Discussion is in full sway about the essence of international law, about its adequacy and its development, and about the factors conditioning its growth and effectiveness. Together with this survey of the entire phenomenon of positive international law, attempts are being made to revise the theoretical construction, the philosophy of, and the method of approach to, international law. The most persistent trend in this discussion seems to be toward a functional conception of international law. As yet there is no agreement as to the exact meaning of functionalism. Perhaps it is not even desirable to define this meaning too rigidly during this early phase of the discussion.

The rights secured by the United States through the conclusion of the Hay-Pauncefote Treaty and the Hay-Varilla Convention afforded the United States legal bases upon which to embark upon the excavation, construction, operation and protection of an interoceanic canal in the Isthmus of Panama. They formed a foundation for the erection of a vast edifice of powers and jurisdiction over the Panama Canal, the Canal Zone, and over vessels and persons in and about the Canal.

I. In the field of international law every subject generally acts in person, through its own organs, without resorting to cooperation with other subjects. However, international practice shows that members of the community of nations sometimes act on behalf of other members, with the legal effect that the transactions performed by the acting subject in the name and for the account of the other have for the latter the same legal consequences as if it had acted in person. This happens, for example, when a state, duly authorized, concludes through its own organs a treaty for another state: the latter is thus bound by the treaty exactly in the same way as if it had concluded the treaty itself, through its own organs. This legal phenomenon implies a split between the immediately acting international person and the person to whom the legal effects of these acts are imputed.

Beginning with participation in the Cape Spartel Light Convention of May 31, 1865, the United States has become a party to about a hundred multipartite administrative treaties, including revisions and amendments of the same. The number of parties to a treaty varies with the treaty, from three or four, as in the case of the Fur Seals Convention of July 7, 1911, to ninety, as in the case of the Universal Postal Convention concluded at Cairo, March 20, 1934. The agreements, usually technical in character, deal with a variety of humanitarian, economic, and cultural subjects, ranging from agriculture to whales. Many of these agreements, such as those dealing with postal matters, publicity of customs documents, and publication of customs tariffs, are primarily of concern to administrative services.