As a Supreme Court justice, Stephen G. Breyer sometimes takes it upon himself to explain what jurists do, thinking that sharing his views will bolster the court's credibility.

That is what Breyer did in 2010 with a book showcasing his idea that the court's power is based on acceptance by the public, since it has no budgetary authority like Congress or executive power like the president.

Now Breyer has written a new book, in which he argues there is a growing need for judges and lawyers in the United States to take foreign laws into account as they seek to resolve disputes that arise not only here but also abroad. In the book, The Court and the World: American Law and the New Global Realities, Breyer says increasingglobal trade and national security crises are forcing U.S. judges to be more mindful of the laws of other nations.

One recent example, he said, was the litigation over suspected eavesdropping by the National Security Agency on foreign citizens.

"What I am trying to do is show how the nature of the court's work has changed," Breyer said in a recent interview with The Inquirer. "Coming into enormous prominence are problems and cases where judges and lawyers have to know something about what is going on beyond our borders, and in doing that I am trying to make very clear that a very abstract interdependence is the nature of today's world."

Breyer will appear at Congress Hall, the corner of Chestnut and 6th Streets, on Thursday at 6 p.m. to discuss his book in a program sponsored by the World Affairs Council, the Center City-based global law firm Morgan Lewis, and Independence National Historical Park. He also was scheduled to speak at the National Constitution Center earlier in the day.

Conservatives recoil at the idea that the U.S. legal system might be somehow subverted by laws that no American lawmaker ever debated, and no president ever signed.

Breyer insisted the need to take foreign laws into account has no ideological basis, but rather emerges from the realities of private trade and civil liberties questions that increasingly reach beyond national borders.

"The best way to preserve American constitutional values is to meet the challenges that the world, as reflected in concrete cases on our docket, actually presents," he writes. "Doing so necessarily requires greater, not less, awareness of what is going on around us."

In his book, Breyer recounts how presidential power through the 19th and early 20th centuries usually went unchallenged by courts. President Abraham Lincoln, after all, seized private companies and suspended the writ of habeas corpus during the Civil War.

And President Franklin Delano Roosevelt expanded the limits of executive authority during World War II by successfully pushing for a trial before a military tribunal for captured Nazi sabatoeurs in 1942, even after the Supreme Court had agreed to hear the case. All but two were executed before the Supreme Court even issued its final opinion in Ex parte Quirin.

Fast-foward to Sept. 11, 2001, and the war on terror that followed. To avoid the reach of federal judges, the Bush administration established the Guatanamo military prison in Cuba. Breyer points out that by the time detainees began to arrive at Guantanamo, the federal judiciary had become much more comfortable in challenging presidential authority and in a series of opinions carved out new legal procedures for determining whether detainees had been held with just cause.

In the same way, federal judges now are pushing out the boundaries of legal analysis to include consideration of international treaties and foreign laws, he said.

Breyer writes that in some ways this is inevitable. There are now some 2,000 commissions, panels and tribunals that exercize authority over American interests and are international in nature. American companies typically submit offshore commercial disputes to international arbitrators who have no institutional connection with the U.S. justice system,he said. Yet those disputes often find their way into U.S. courts, which must decide whether cases had been correctly subjected to arbitration in the first place.

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