A former CIA analyst and an American law professor are scheduled to testify against the United States at a hearing in the World Court next week on Nicaraguan charges that Washington is violating international law by supporting rebels trying to overthrow the Sandinista government.

Paul Reichler, a Washington lawyer representing Nicaragua in the case, said that "old hands at the court" in The Hague believe that it is the first time lawyers and witnesses have opposed their own country in the court. He added that American Judge Stephen Schwebel had voted against the United States in preliminary proceedings, another first for the court.

The two U.S. witnesses scheduled to testify on behalf of Nicaragua are David MacMichael, who worked at the CIA as a contract employe from 1981 to 1983, and Michael J. Glennon, a professor at the University of Cincinnati who went to Nicaragua in February to investigate reports of atrocities by the U.S.-supported rebels known as contras, or counterrevolutionaries.

Abram Chayes, a former Kennedy administration official and professor at Harvard Law School who also is representing Nicaragua in the case, said Managua contends that the United States violated international law by funding, organizing, controlling and directing the anti-Sandinista rebels.

The lawyers said they would present evidence casting doubt on the stated U.S. reasons for backing the rebels as well as information on the extent of the U.S. aid. Two Nicaraguan officials -- Deputy Interior Minister Luis Carrion and Finance Minister William Hupper -- also are scheduled to testify.

The United States withdrew from the case in January, saying that the court did not have the right to decide a political matter. Washington also said the U.S. role in Central America was a matter of self-defense because Nicaragua was aiding rebels fighting to overthrow the government of El Salvador, a U.S. ally.

Chayes said that even though the United States does not recognize the jurisdiction of the court in the case, a decision favorable to Nicaragua "will be taken very seriously" in Western European and Latin American countries whose economic and political support is important to the Sandinistas.

He added that although "the United States is not likely to change its policy" of opposing the Sandinistas, that policy is "under continuous discussion" in Congress and among the general public and an "authoritative statement" by the World Court that the policy is illegal could affect that debate.

Glennon, the University of Cincinnati law professor, said he had decided to testify for Nicaragua because he had found evidence of "terroristic violence directed against civilians" by the contras. "I have a responsibility to make available relevant information in my possession," he added, saying this was "in the highest tradition of the American people."

Two days before Nicaragua presented its case to the court in April of last year, the United States -- anticipating the move -- declared that it would not accept the court's jurisdiction over U.S. actions in Central America for the next two years. It continued to be represented, however, by a State Department legal adviser.

A month after Nicaragua brought the case, the World Court, formally known as the International Court of Justice, voted to urge the United States to stop mining Nicaraguan harbors and to end all activities that jeopardize Nicaragua's "sovereignty and independence."

Judge Schwebel voted with the rest of the court on the first part but dissented in the second.

In November, the court rejected the U.S. argument that it lacked jursidiction in the case, opening the way for the hearings on the merits that begin Thursday.

In January, the United States announced that it was withdrawing from the case, saying, "The conflict in Central America . . . is not a narrow legal dispute; it is an inherently political problem that is not appropriate for judicial resolution."