Regardless of what interrogation strategy is used, the prime goal for the interrogator in a just, democratic society with the rule of law must be to get to the truth. Torture can never be a method for getting to the truth (as daisym explained). Thus, you don't have to be a proponent of human rights in order to oppose torture, it is sufficient that you want interrogators to get the truth out of the interrogated people.

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President Josiah Bartlet: Sweden has a 100% literacy rate. 100%! How do they do that?
Leo McGarry: Maybe they don't and they can't add.