Like it or not torture has been used by states for thousands of years. Until someone says that torture never works and can back it up with empirical evidence not supposition we may need to go the extra mile or fingernail some day to save American lives. The Constitution is not a suicide pact.
"Then the herdsman, as they were dragging him to the rack, began at the beginning, and told the whole story exactly as it happened, without concealing anything, ending with entreaties and prayers to the king to grant him forgiveness." ca 540 BC
Herodotus' History