There is a disconcerting pick-up-your-marbles appearance to the administration's decision to terminate the United States' 39-year-old declaration accepting the compulsory jurisdiction of the World Court. It looks as though this country merely decided it was taking too much heat in Nicaragua's current suit alleging that American support of the contras violates international law. Not many Americans may know exactly what international law is, but it is something of an article of national faith that American conduct in the world should be in conformity with it. The spectacle of the United States walking off the field is not a pleasant one.

In fact, the reality differs from the appearance. American acceptance of the compulsory jurisdiction of the International Court of Justice in political cases (on a reciprocal basis) represented the part of the American postwar outlook holding that the terrible conflagration of World War II could usher in a rule of law. Few countries -- no unfriendly ones -- ever followed the American example. At that, the United States ruled its domestic affairs out of the court's jurisdiction and made plain that it would not allow it to compromise American security. So it jarred many American lawyers, including those with no sympathy for President Reagan's foreign policy, when the court in Nicaragua asserted jurisdiction for the first time in a continuing armed conflict.

But that does not fully explain the administration's reaction. Insisting that the court is essentially a political forum, and an unfriendly one, the United States declined to stand up to Nicaragua's charges and to avail itself of the opportunity to present the American counterclaim that the Sandinistas are subverting their neighbors. The United States could have considered withdrawing partially from the court's compulsory jurisdiction, making the national security reservation that other states have made. Instead it withdrew entirely.

A strong argument can be made that the World Court made a mistake by taking the Nicaragua case; the dispute between Managua and Washington is political and should have gone to a political forum -- the United Nations. At this late date, furthermore, few people mistake the court for mankind's last best hope. But it is an institution with its modest uses, and the United States, as the preeminent country of law in the world, has a greater interest than any other in seeing it strengthened, not diminished.