The Supreme Court kicked off its new term on Monday, struggling to clarify when foreign victims of torture and other crimes against humanity can sue corporations and others in federal courts.
The outcome could have significant global impact from a moral, political, and financial perspective.
At issue, is the scope of a federal law that is increasingly being used in an effort to hold those accountable for human rights atrocities committed overseas.
A dozen Nigerian political activists now living under asylum in the United States claim foreign oil companies were complicit in violent abuse at the hands of their former country's military. The decade-old lawsuits have been blocked from going to trial in American courts.
The Obama administration is siding partly with the foreign businesses.
The justices first heard the case in February, trying to sort out whether individuals alone -- or political groups and corporations also -- are covered by broad civil immunity for alleged international law abuses.
Now the court will decide that and a more fundamental question: whether the 1789 federal law can be applied to any conduct committed entirely outside the United States.
"Do you disagree [there] are fair [international] judicial systems where a plaintiff can get a fair shake?" said Justice Samuel Alito, reflecting general conservative skepticism. "If that's so, then why does this case belong in the courts of the United States, when it has nothing to do with the United States other than the fact that a subsidiary of the defendant has a big operation here?"
But other justices said federal courts for two centuries were open to such foreign claims, initially in response to piracy on the high seas.
"We gave a stamp of approval" to such lawsuits in a 1980 case, said Justice Elena Kagan, "understanding that there were certain categories of offenders who were today's pirates."