A United States Supreme Court judge says it is not clear that the American constitution protects people from torture.

Justice Antonin Scalia says the constitution prohibits cruel and unusual punishments.

But he says it would be absurd not to inflict pain on someone when they had key knowledge of an imminent attack.

"Once you acknowledge that we're into a different game, how close does the threat have to be and how severe can the infliction of pain be?" he asked.

"I don't think these are easy questions at all, in either direction, but I certainly know you can't come in smugly and with great self-satisfaction and say, 'oh it's torture and therefore it's no good'," he said.

"You would not apply that in some real life situations."

- BBC