Can torture save American lives? Yes. But so can many things such as universal health coverage or allowing members of the public to buy a new wonder drug prior to FDA approval. The question that needs to be asked is "at what cost?". Can torture ever be the right thing to do? Yes. Should it be legal? No.
I can understand a CIA operative feeling justified in torturing a terrorist to save lives, just as I could understand a cop feeling justified in torturing a kidnapper or pedophile to save the life of a child in imminent danger. Just because I would probably want to contribute to the legal defense fund of said cop or operative (especially if he had tortured the right individual) does not mean I believe it should be legal.
The cost of institutionalizing torture, allowing it to become part of the ‘American Way’, simply bears too high a price.