By Jonathan Stempel

Oct 1 (Reuters) - The U.S. Supreme Court, back in session today after its summer recess, is expected to take up a closely watched case that could help it decide whether American judges are empowered to hear lawsuits over human rights atrocities abroad.

The nine justices will review the reach of the Alien Tort Statute, an obscure 1789 law that was revived in the 1980s by attorneys pursuing international human rights cases.

In the past two decades more than 150 Alien Tort Statute lawsuits, accusing U.S. and foreign corporations of wrongdoing in more than 60 foreign countries, have been filed in U.S. courts, according to the U.S. Chamber of Commerce.

Last February, during the first oral arguments in Kiobel v. Royal Dutch Petroleum, some of the court's conservative justices signaled a willingness to shield corporations from liability in U.S. courts over allegations that they had aided or acquiesced to foreign governments that abused their own people.

On March 5 the justices asked both sides to reargue the case and address a larger question about the Alien Tort Statute: whether U.S. courts should be open to similar claims brought against anyone, not just corporations.

Arguments are set to take place eight years after the court in Sosa v. Alvarez-Machain, which concerned the forced abduction from Mexico of a suspect in a murder, said an Alien Tort Statute claim that rested on "a norm of international character accepted by the civilized world" could be brought in U.S. courts.

Of the cases in the new nine-month term, "Kiobel raises perhaps the largest question of them all: the relationship between America and the world," said Douglas Kmiec, a law professor at Pepperdine University in Malibu, California, and former U.S. ambassador to Malta.

"The notion that Sosa v. Alvarez-Machain left open the door for a cause of action rocks the foundation o f international human rights law in a good way, because most of human rights is diplomatic and aspirational, not enforceable," he said.

Rehearings are rare and often foreshadow landmark rulings. Examples include the 1954 Brown v. Board of Education school desegregation case and the 2010 Citizens United v. Federal Election Commission case allowing unlimited spending by corporations and unions in elections.

Several dozen briefs have been filed in the case, representing groups such as Serbian genocide victims, companies such as Coca-Cola Co and mining giant Rio Tinto Plc, and countries such as Argentina, Germany and the United Kingdom.

NIGERIAN DICTATORSHIP

The Alien Tort Statute lets federal courts review "any civil action by an alien for a tort only, committed in violation of the law of nations or a treaty of the United States."

Twelve Nigerian plaintiffs led by Esther Kiobel used it in litigation accusing oil companies of complicity in a crackdown on protesters - including torture, executions and other crimes against humanity - by military ruler Sani Abacha from 1992 to 1995. Kiobel's husband, Barinem, a local politician, and others were among those executed.

In the original Feb. 28 argument, Justice Samuel Alito revealed unease about letting U.S. courts reach out to address such cases and suggested that doing so could heighten international tensions.

"What business does a case like that have in the courts of the United States?" he asked. "There's no connection to the United States whatsoever."

Meanwhile, Justice Anthony Kennedy, known for looking to international legal practices for guidance, quoted from a Chevron Corp brief stating that no other countries give their courts "universal civil jurisdiction" over human rights abuses to which those countries have no connection. Kennedy is often a swing vote on the court.

The high court has recently made it harder for other plaintiffs to sue in U.S. courts over non-U.S. conduct.

In April it said civil lawsuits brought under the 1991 Torture Victim Protection Act on behalf of victims of killings and torture can be brought only against individuals, not groups such as the Palestinian Authority.

Prior to that, in 2010, the court shut down many foreign securities fraud claims in Morrison v. National Australia Bank Ltd, in which it concluded that U.S. statutes face a "presumption against extraterritoriality."

In a court brief, Germany cited that case in urging a narrow reading of the Alien Tort Statute, saying "overbroad exercises of jurisdiction" make it harder for sovereign countries to control their affairs.

Some say others might take matters in their own hands.

"If the court says there is no limitation on jurisdiction, we can be certain that other nations will retaliate, and use their courts to expand economic or political power," said Matthew Kemner, a partner at Carroll, Burdick & McDonough in San Francisco who submitted a brief supporting Royal Dutch Petroleum on behalf of a group of international law professors.

But supporters of the Nigerian plaintiffs say resistance elsewhere to addressing human rights abuses justifies allowing U.S. courts to step in.

"People are asserting universal human rights, but there are many countries that don't provide a viable forum, so if the U.S. and similarly situated countries don't provide that forum, then those rights are meaningless," said David Sloss, a professor at Santa Clara University School of Law who submitted a brief in favor of the Kiobel plaintiffs on behalf of Navi Pillay, the U.N. High Commissioner for Human Rights.

U.S. URGES RESTRAINT

The Obama administration has urged that the court not adopt a categorical rule allowing lawsuits over extraterritorial conduct.

It argued that courts instead could on a case-by-case basis allow claims based on conduct that might interfere with U.S. foreign relations or respect for human rights, such as torture and killings that foreign governments encourage or tacitly permit.

Sloss said the Supreme Court could decide to end use of the Alien Tort Statute in "foreign-cubed" cases: foreign defendants suing foreign companies over conduct outside U.S. borders.

Kmiec said a limited ruling was possible and noted that the law was adopted at about the same time as the Constitution.

"I don't expect the court to be as categorical with the presumption against extraterritoriality as corporations hope," he said. "The pedigree of the Alien Tort Statute will have to be reconciled with our adherence to international law in the way a more modern statute might not."

The case is Kiobel v. Royal Dutch Petroleum Co, U.S. Supreme Court, No. 10-1491.

Follow us on Twitter @ReutersLegal | Like us on Facebook