To Justice Breyer,the Supreme Court serves as a patrol, interpreting the Constitution to ensure that the democratic system it created is functioning without flying off the rails.

The associate justice outlined his vision of the Constitution and the role of the country’s highest court in a lecture at New York Law School in TriBeCa yesterday. America’s founding document, he said, was intended to foster a notion of “active liberty,” in which citizens can govern themselves and participate freely in the democratic process.

“The Constitution doesn’t tell people what to do,” Justice Breyer said, speaking before an audience of nearly 200 people. “The Constitution does set up a system so that people can decide for themselves what to do.”

Justice Breyer offered his view of the Constitution by way of explaining his decision to pen a book,”Active Liberty: Interpreting Our Democratic Institution,” which came out last year. It is the justice’s first since President Clinton named him to the bench in 1994. Justice Breyer, 67, is known as one of the court’s more liberal jurists, and his vision of the Constitution differs from the narrow interpretations used by the court’s most conservative justices, Antonin Scalia and Clarence Thomas.

In Mr. Beyer’s view, the Constitution enables a system of democracy that operates within boundaries that “need patrolling,” which is where the court comes into play. “We’re seeing if that system goes off the rails,” the justice said of the Supreme Court’s role. The job of the court, he said, is to resolve disputes that occur at the outer reaches of the democratic system.

Justice Breyer tread carefully to avoid giving his opinion on cases that may yet appear before the court, echoing a refrain often heard during the recent confirmation hearings of Chief Justice Roberts and Justice Alito. “If anybody thinks I said anything about any case in front of us, I didn’t,” Justice Breyer joked.

Answering questions from the audience after his lecture, Justice Breyer defended the use of international law in deciding a case and called the 2000 decision that elevated George W. Bush to the presidency one of the toughest cases in his nearly 12 years on the court. The justice also joked that because of the recent appointments by President Bush, he had missed by a month the record for being the court’s junior member the longest. The junior member traditionally must get up to answer the door of the conference room, a task Justice Breyer said he gladly passed on to Mr. Alito.

The use of international law erupted into a political controversy in 2005 after Justice Scalia sharply criticized a majority opinion written by Justice Kennedy – and joined by Justice Breyer – that acknowledged “the overwhelming weight of international opinion” in striking down a law that permitted executions of juveniles.

Justice Breyer said there was nothing wrong with considering a foreign opinion in deciding a Supreme Court case. “I might decide it’s wrong, but why not read it? I might learn something,” he said.

Critics of using international opinions, he said, were afraid that justices might adopt foreign values in formulating their views. “Its very unlikely that reading an opinion from some other place is going to change my values, or those of the Constitution,” Justice Breyer said.

The 5-4 decision in Bush vs. Gore, in which Justice Breyer dissented, was “stressful,” he said. But the tone of the debate was civil, as always.”People didn’t shout at each other,” he said. “I have never heard a voice raised in anger in that conference room.”