Unlike the rendition cases of Maher Arar and Khaled El Masri, the case of Zammar is more difficult. Maher Arar and Khaled El Masri were the victims of mistaken identity, whereas Zammar was very much a terrorist. There are few who would dare protest the torture he is undergone, which has been confirmed by Maher Arar, who was aware of his presence in a prison he stayed at in Syria. But MEP Cem Ozdemir is one person who has stood up and decried Zammar's torture.
It goes back to the old dilemma; if torturing someone meant that he would give you information that would save thousands of people from a terrorist attack, isn't it worth it? This assumes that torture elicits truth rather than fear. Or that it elicits something other than what U.S. servicemen are trained to offer up: tidbits that are confirmable and no big chunks of information so that they can stall their captors. Or that those who are being tortured have not been brainwashed to no longer care about death or death threats.