Sarah Montague talks to Juan Mendez, the United Nations' special rapporteur on torture. He was a human rights lawyer in Argentina in the 70s when he was arrested, imprisoned and tortured. He has said he owes his life to those in America who took a principled stand against torture. But now Juan Mendez says the world has become more accepting of cruelty and America has been compromised by its own brutal treatment of prisoners. So is torture ever morally justifiable?