The idea of establishing a world judicial body was not originated in Paris in 1919, but had been discussed on many occasions, most recently at the Second Hague Conference in 1907.
The Covenant of the League of Nations called for the creation of such a body with judges to be selected by the league’s council and assembly from a list of nominees submitted by the Hague Court of Arbitration. Despite not being a member of the League, the United States sent the distinguished diplomat Elihu Root to assist in the drafting of the court’s protocol or constitution.
The expectation was that the U.S. would participate actively in the court. A recommendation to that effect was made by Secretary of State Charles Evans Hughes, who urged President Harding to act favorably on the matter. The League of Nations attempted to smooth the way by making an exception to its rules and allowing a non-member to have a role in naming judges to the court.
Despite the efforts of the forces favoring American participation, isolationists in the Senate succeeded in blocking ratification of the court’s protocol. They feared that membership in the judicial body would be a first step toward membership in the League of Nations.
During the Coolidge administration, American public opinion continued to oppose any thought of membership in the League of Nations, but favored "adherence" to the World Court. Both political parties gave support to those views in their platforms in 1924. However, the Irreconcilables in the Senate feared that cooperation with the court might be used as a backdoor entry into the league, and, indeed, many supporters of the court hoped that to be the case. Foes of the court on the Senate Foreign Relations Committee succeeded in blocking for some time a Senate vote on the protocols for adhering to the court. They and their colleagues on the committee also added a series of reservations, aiming to secure independence from the league as well as equal status with other members. When a Senate vote was finally forced through cloture in January 1926, the protocols with reservations were ratified 76 to 17. Regrettably, when presented to the World Court members for their approval, parts of the reservations proved unacceptable to them. On November 11, 1926, President Coolidge, recognizing that the senate would not consider revising its reservations at that point, announced that the United States would not join the court.
Informal efforts — centering around Root — to correct the difficulties began soon thereafter. It took time and effort to work out the complexities involved, but they were successfully resolved as the Coolidge Administration came to an end and their resolution was officially announced shortly after Hoover's inauguration on March 4, 1929. Joining the court was still important, because the World Court complemented the Kellogg-Briand Pact, which was being implemented at the time — the two went together, as was recognized then.
Hoover, however, failed to submit the revised protocols for approval of the Senate before the problems of the Depression took center stage. As a result, it was not until 1935 that FDR submitted the revised protocols to the Senate. There was a battle cry of popular opposition (Huey Long, Father Coughlin, the Hearst press led the charge) and the protocols were defeated.
Even though the United States was not a member, a number of distinguished American jurists served on the court, including John Bassett Moore, Hughes and Frank B. Kellogg.
See other diplomatic issues during the Harding and Coolidge administrations.