In the wake of the Sept. 11, 2001, attacks, Seton Hall University Law School students clamored to sign up for a new seminar titled "Terrorism and Civil Liberties." Besides the timely topic, the limited-enrollment class had a professor of some prominence: U.S. Appeals Court Judge Samuel A. Alito Jr.

Alito's nomination last week for the Supreme Court means that his former students gained far more than legal education. Two hours a week, for 14 weeks, they witnessed the workings of Alito's legal mind on a crucial frontier of law he will help define if he is confirmed: the tension between individual constitutional rights and what President Bush calls the war on terror. On Monday, the Supreme Court agreed to hear a constitutional challenge this spring to the Bush administration's use of military tribunals to try foreign terrorist suspects.

There was no hint, Alito's former students said, that he had resolved the tension in his own mind -- only that he was wrestling intellectually with it. He told them the course was an academic exercise for him as well as them because there is little guidance in the Constitution or case law for where executive power ends and civil liberties begin in times of national emergency.

His questions pushed them sometimes to the right, sometimes to the left, but never to a conclusion, they said, as they debated the constitutionality of the USA Patriot Act, military tribunals, detention of enemy combatants without trial, expanded use of electronic surveillance and more.

"One of the great things about the class was if you went in knowing his conservative reputation, you came out questioning that reputation," said Robert G. Marasco, who took the class in 2003 and is now an associate at Gibbons, Del Deo in Newark. "I had no idea where he stood afterwards or if he has even reached a conclusion of his own."

Marasco was surprised when Alito gave him an A on his final paper, in which he said he took "an extremely liberal position, for the sake of argument" on the constitutional rights of suspected terrorists. Jacqueline C. Pirone, who took the course in 2004 and is now an associate at Jackson, Lewis in Morristown, N.J., remembered taking the opposite position in many class discussions, and getting an A-minus.

One day in February 2004, Alito created a hypothetical scenario for his students: The government had captured a foreign terrorist believed to be en route to an attack that would kill thousands of Americans. Was it constitutional for U.S. interrogators to use torture if by doing so they could thwart the attack and save American lives? Should there be a "ticking time bomb" exception to protect citizens against terrorism?

Alito did not answer the question, instead leaving the students to debate it, according to an account at the time in the Bergen Record. "If we do the things that we criticize other nations for doing, it makes us no better than those nations," student Naazneen Khan was quoted as saying.

Pirone said she argued the other side. "The 9/11 attacks happened in our first week of law school. Students watched the towers fall with their own eyes. Everyone knew someone in there. My attitude was: It's wartime, and you do what you have to do," she said.

"In a lot of law school classes, professors would tell us what we should get out of a case," said Joseph Arnold, a 2003 student of Alito's and now an associate at a law firm in Philadelphia. "With Judge Alito, we would come to a point where we had exhausted the case law and there would be this awkward silence where you're thinking, 'Let's see what the judge is going to say.' But that silence was never filled. He'd just give a shrug of the shoulders, as if to say, 'Now you see that there isn't that ultimate answer.' "

Marasco said, "You got the feeling that because of the enormity of the issues upon us, he himself didn't fully grasp what could happen."

Alito taught the course in a small seminar room in the bottom floor of the law school in downtown Newark. Dean Patrick E. Hobbs said the judge suggested the course because "these issues, while certainly not new, were in a new context."

Alito taught often as an adjunct at Seton Hall, which former dean Ronald J. Riccio called "a window onto him -- he did it because he wanted to help young people. If he was paid anything, it was minimal."

The syllabus in the terrorism course spanned landmark cases of presidential power in wartime from the Civil War to the present, including the widely denounced Korematsu decision upholding internments of Japanese Americans during World War II and recent rulings finding the Bush administration in violation of the Constitution for holding American citizens Yaser Esam Hamdi and Jose Padilla as enemy combatants.

"He would ask questions, in the case of the Patriot Act, like: Did the government have the authority to assume these powers? Even if they have the power, have they done so in a fashion that is overly broad and exceeded their constitutional powers?" Marasco recalled.

Alito also guided his students to one of the central constitutional questions about what the Bush administration has called the global war on terror. Bush has argued that the battlefield in this war spans the world. Students who saved their notes said Alito asked questions such as "Where is the battlefield? Afghanistan? America?" And: "When does the war end?"

Legal scholars point out that courts have deferred to the executive in wartime, but the deference ended when the wars did. A "war on terror," by contrast, is open-ended. As a result it may ultimately be up to the Supreme Court -- and a Justice Alito, if he is confirmed -- to end the war in terms of the status of constitutional rights.

"Obviously the Supreme Court will have to come up with rules that define when we go back to the normal legal requirements, especially about due process," said Ronald Chen, associate dean for academic affairs at Rutgers Law School, who has represented civil liberties plaintiffs in cases after Sept. 11.

The Supreme Court has already begun the process. Justice Sandra Day O'Connor, whom Alito would replace if confirmed, wrote of the Hamdi case: "A state of war is not a blank check for the president when it comes to the rights of the nation's citizens."

Although Alito kept his opinions to himself, his students emerged with their own perspectives. Pirone said she saw some parallels between certain civil liberties issues today and the World War II internment of Japanese Americans based on race alone. As Alito pointed out, the Supreme Court deferred to then-President Franklin D. Roosevelt and upheld the internments as constitutional.

"Can we be that quick to criticize Korematsu when we have the Patriot Act chipping away at our civil liberties?" Pirone asked. "You wonder if we'll adapt differently this time. The lesson for me was that in times of crisis, the courts and the other two branches have to sort it out, with not a lot to go on. The more things change, the more they remain the same."