Defendants in the 40-year-old Supreme Court decisions that were used to justify wartime internment of 110,000 Japanese Americans are planning to seek a reopening of their cases, citing postwar evidence that the government withheld crucial information from the court.

The information, including Navy and FBI intelligence reports then in government possession, contradicted the government's claim at the time that "military necessity" required the curfews and evacuation orders imposed on the Japanese Americans. That claim formed the core of the rulings.

The defendants seek an unprecedented Supreme Court admission of error in the cases that would nullify their convictions for violations of restrictions and serve as a powerful symbol of apology by the court at a time of revived interest in the Japanese-American community about the internment.

The decisions in Yasui vs. U.S., Hirabayashi vs. U.S. and Korematsu vs. U.S. are cited as a low point in the court's history, comparable to the pre-Civil War Dred Scott ruling justifying slavery, because the court uncritically allowed the government to take action based solely on the victims' race at the time of World War II when Japan was an American enemy.

The wartime internment in desolate barbed-wire camps is widely regarded now as a gross injustice, the product of hysteria and racism following the Japanese attack on Pearl Harbor.

A congressionally established wartime relocation commission is considering redress for victims and their heirs.

Experts, in interviews, could recall no occasion when the Supreme Court agreed to reopen such a major case. Two of the defendants, Gordon Hirabayashi and Minoru Yasui, believe the effort will have important symbolic significance even if unsuccessful.

"We are trying to preserve the constitutional principles of our country," said Yasui, a lawyer and director of the Denver Human Rights Commission. "In this country, we try to rectify our errors. The possibilities are not good, but it seemed to me we ought to make the effort."

A Supreme Court reversal would work little or no change in the law since subsequent rulings in unrelated cases, though not wartime cases, have dramatically expanded safeguards for racial minorities.

Yasui said the defendants were "aiming" for Dec. 15 to file petitions, possibly in the U.S. 9th Circuit Court of Appeals in California, to have their convictions and related rulings declared errors.

Hirabayashi, a professor of sociology at the University of Alberta in Canada, said lawyers had been working on the petitions for months in Seattle and San Francisco under the leadership of Peter H. Irons, a lawyer and scholar researching a book on the cases.

Irons said this weekend that he had found new information about alleged "destruction" of evidence by the government during the war that will form the basis for seeking a reopening.

But he declined to provide details unless The Washington Post agreed not to publish them until the petition is filed in December.

The government's case and the court's rulings were based largely on statements by the West Coast military commander, Gen. J.L. DeWitt, who later became famous for declaring that the Japanese were "an enemy race."

DeWitt spoke of reports of "fifth column" activity and mysterious signaling from the shore to Japanese ships, among other things, in arguing potential disloyalty of Japanese Americans.

The court cited these claims in support of its unanimous ruling in the Hirabayashi case. All of the claims later proved unfounded, and no sabotage or attempted sabotage by a Japanese American has been proven.

Among other things, the government did not provide the court with Navy and FBI intelligence reports saying evacuation was unnecessary. FBI Director J. Edgar Hoover, for example, told President Roosevelt that "the necessity for mass evacuation is based primarily upon public and political pressure rather than on factual data."

These documents became available after the war and have been authenticated and cited by historians.

Irons presented some of his case for reopening to the commission studying redress in a hearing last December, saying he had additional documents showing internal debate in the Justice Department about the ethics of withholding such data.

Hirabayashi and Yasui were convicted of violating the 8 p.m.-to-6 a.m. curfews imposed on Japanese Americans after the Pearl Harbor attack Dec. 7, 1941. Fred Korematsu was convicted of challenging DeWitt's order "excluding" Japanese Americans from parts of California, Oregon and Washington.

The Hirabayashi and Yasui cases were resolved unanimously June 21, 1943, by a court composed of Chief Justice Harlan Fiske Stone and Justices Owen J. Roberts, Hugo L. Black, Stanley Reed, Felix Frankfurter, William O. Douglas, Frank Murphy, Robert H. Jackson and Wiley Rutledge.

The court decided the Korematsu case Dec. 18, 1944, with Black writing and dissents by Roberts, Murphy and Jackson.

After the war, Yale Law School professor Eugene V. Rostow wrote a now-celebrated Yale Law Journal article attacking the court's failure to reexamine the basis of the claim of military necessity and calling the rulings "potentially a major breach in the principle of equality."

Former Supreme Court justice Arthur J. Goldberg, a member of the commission studying redress, recently called Korematsu "one of the most ill-conceived decisions handed down by the Supreme Court, perhaps second only to Dred Scott vs. Sanford."

But in a widely circulated letter to commission member William M. Marutani, a Philadelphia judge, he questioned the wisdom of reopening it. It "runs the danger of legitimating this bad decision, in public perception, in the virtually certain event of denial by the court of reopening the case," Goldberg wrote.

The wartime relocation commission has been considering recommending congressional action to help reopen the case.