After 1898 the United States not only solidified its position as an economic colossus, but by annexing Puerto Rico and the Philippines it had also added for the first time semi-permanent, heavily populated colonies unlikely ever to attain statehood. In short order followed a formal protectorate over Cuba, the "taking" of Panama to build a canal, and the announcement of a new Corollary to the Monroe Doctrine, proclaiming an American duty to "police" the hemisphere. Empire had been an American practice since the nation's founding, but the new policies were understood as departures from traditional methods of territorial expansion. How to match these actions with traditional non-entanglement constituted the central preoccupation of U.S. foreign relations in the early twentieth century.
International lawyers proposed instead that the United States become an impartial judge. By becoming a force for law in the world, America could reconcile its republican ideological tradition with a desire to rank with the Great Powers. Lawyers' message scaled new heights of popularity in the first decade and a half of the twentieth century as a true profession of international law emerged. The American Society of International Law (ASIL) and other groups, backed by the wealth of the Carnegie Endowment for International Peace, held annual meetings and published journals.