If the new brain science were foolproof, it could bring powerful new evidence to criminal cases. Already, legal experts say the latest brain techniques are influencing the outcomes of trials across the country. But many researchers warn that brain science as courtroom evidence may be, as Perry Mason used to say, incompetent, irrelevant and immaterial. There is no doubt, researchers say, that modern science is getting closer to learning how the brain shapes people's actions and abilities. Certain regions of the brain are known to be devoted to seeing or listening, planning or remembering.
Scientists can watch the waxing and waning of delicate nerve cell connections that seal in memories.
High-tech scanners can capture thoughts flickering through the brain. Other research suggests that damage to tissue in the front of the brain causes personality traits often seen in criminals. Recordings of brain electrical activity, some scientists say, can show whether someone is lying or telling the truth. An Iowa judge, for instance, is now deciding whether to admit as evidence brain-wave test results that a man says should clear him of a 1977 murder. In the Iowa case, news accounts say, the real murderer escaped by running behind a building through tall weeds.