Yet another reason...  

To disregard confessions. [Especially torture-enhanced "confessions"].

One of the most recent papers on the subject, published in Law and Human Behavior by Saul Kassin and Jennifer Perillo of the John Jay College of Criminal Justice in New York, used a group of 71 university students who were told they were taking part in a test of their reaction times. Participants were asked to press keys on a keyboard as they were read aloud by another person, who was secretly in cahoots with the experimenter. The volunteers were informed that the ALT key was faulty, and that if it was pressed the computer would crash and all the experimental data would be lost. The experimenter watched the proceedings from across the table.
In fact, the computer was set up to crash regardless, about a minute into the test. When this happened the experimenter asked each participant if he had pressed the illicit key, acted as if he was upset when it was “discovered” that the data had disappeared, and requested that the participant sign a confession. Only one person actually did hit the ALT key by mistake, but a quarter of the innocent participants were so disarmed by the shock of the accusation that they confessed to something they had not done. [More worth reading]

We are hard-wired to lean toward confessing just to end an unpleasant current experience. This physiological fact makes those who resist torture all the more heroic, IMHO, and those who use torture all the stupider.