The two justices, Antonin Scalia and Ruth Bader Ginsburg, made the comments during a public event at the National Press Club in Washington. They were responding to questions posed by journalist Marvin Kalb about whether the court would take up cases arising from the recent disclosures about NSA surveillance, most notably by former NSA contractor Edward Snowden.
The justices did not discuss specific NSA programs. There are various lawsuits pending around the country challenging the government's widespread collection of telephone records. A federal judge in Washington, D.C., ruled in December that the program was probably unlawful, while a judge in New York held later that month that it was not. Both cases are now on appeal.
Scalia, a leading conservative justice, said the court was not the best body to decide major national security issues because of its lack of expertise. But he indicated that the court would likely decide the issue of whether widespread gathering of telecommunications data violates the Fourth Amendment, which bars unlawful searches and seizures.
"The institution that will decide that is the institution least qualified to decide it," Scalia said. The legal question is about "balancing the emergency against the intrusion" on the individual, he said.
Nine justices serve on the U.S. Supreme Court.
Ginsburg, one of the court's liberal members, said the justices would have little choice but to decide the matter should it come before them.
"We can't run away and say, 'Well, we don't know much about that subject so we won't decide it,'" she said.