It has been a stain on the nation's conscience for five decades, a shameful mistake for which apologies have been made and reparations paid.

In the courts of public opinion and history, the detention of more than 110,000 U.S. residents of Japanese ancestry during World War II was repudiated long ago.

But at the U.S. Supreme Court, where the policy was held constitutional in 1944, the case of Korematsu vs. United States has never been reconsidered. Some legal scholars of varying political views have said that in the aftermath of the Sept. 11 terrorist attacks, the long-derided Korematsu decision could be invoked again to restrict civil liberties in ways most Americans would have thought unthinkable just five weeks ago.

"Korematsu has been severely criticized in peacetime, and I emphasize in peacetime," said Douglas Kmiec, a legal scholar and former assistant attorney general in the Reagan administration. "It has never been overruled."

Jerry Kang, a law professor at the University of California at Los Angeles, said the infamous decision is still considered "good law."

"I think we have too easily said that we have learned the lessons of Korematsu," Kang said. "One could imagine similar deprivations, I think, of Arab-American civil liberties on the grounds of military necessity."

And though the wholesale internment of Arab Americans seems improbable, some scholars say the likelihood of severe and perhaps selective restrictions of liberty for Arab Americans could increase dramatically if there are further terrorist strikes

A growing body of more recent law ensuring equal protection stands in contrast to the Korematsu decision's validation of race-based policy. And, in the past month, President Bush and others have argued forcefully against lashing out at Muslims and Arab Americans.

But already the signs of a jittery public are rampant: A letter with a Saudi Arabian postmark prompts an evacuation at city hall in Bridgeport, Conn. A resident tells state police in Colchester, Conn., that Middle Eastern neighbors are arguing loudly -- and may be terrorists. The FBI is contacted when the owner of an East Windsor, Conn., convenience store abruptly returns to his native Pakistan.

"If more attacks come on the order of 9/11, all bets are off," Kang said. "It's when the next shoe drops that we're really going to test the mettle of the nation."

History makes clear that, when national security is at issue, civil liberties -- rightly or wrongly -- are among the first casualties.

Abraham Lincoln suspended the writ of habeas corpus, by which prisoners ask judges to review the legality of their confinement, during the Civil War. Suspected communists were deported during the McCarthy era. Since the Oklahoma City bombing, the Immigration and Naturalization Service has been permitted to use secret evidence, kept even from the defendant, in detention and deportation proceedings against noncitizens suspected of being terrorists.

In a recent book on civil liberty and wartime, Chief Justice William H. Rehnquist defended much of the Korematsu decision, including the central principle that courts must defer to the government where national security is at stake. Rehnquist alluded to the ancient legal maxim -- inter arma silent leges -- that in times of war, the law is silent.

"It is neither desirable nor is it remotely likely that civil liberty will occupy as favored a position in wartime as it does in peacetime," Rehnquist wrote in "All the Laws But One," published in 1998. "The laws will thus not be silent in times of war, but they will speak with a somewhat different voice."

Detention camps

In 1942, that different voice came in the form of Executive Order 9066. Three months after Pearl Harbor was attacked, President Roosevelt granted the secretary of war power to designate certain regions as "military areas" in which travel might be restricted and certain people excluded.

In less than a month, amid fear of espionage and sabotage, the entire West Coast had become such an area. By August, more than 110,000 people of Japanese extraction -- 77,000 of them U.S. citizens -- were removed from their homes and interned in 10 detention camps in Arkansas, Utah and Wyoming.

Fred T. Korematsu, born in the United States to Japanese parents, was at the time a young man working as a welder in San Francisco shipyards. He had twice tried to enlist in the Army but was rejected because of a physical disability. Hoping to remain with his Italian-American girlfriend, Korematsu defied the order and tried to remain, unnoticed, in the Bay Area.

He was arrested in May 1942.