This is one of the best, brief discussions I've heard of the current status on how modern neuroscience is being used in modern criminal and civil courtrooms and what may be possible in the future.
Greely calls "reckless at this point" (at least) two companies which are already out selling "lie detection" services as potetial expert witnesses using fmri's. But the evidence, he says, at this point does not justify anyone buying such services or admitting it in court.
Along with "pain detection" and "bias detection," however, lie detection is an area where current research is fervently looking for practical applications in the courtroom. Modern neuroscience might also change how courts view insanity defenses, said Greely, though he emphasized that available technology and science doesn't yet necessarily disturb these issues.
If the science is ever perfected, which he emphasizes is a big "if," Greely predicts many other bothersome but interesting Fourth and Fifth Amendment questions facing the courts as a result of evolving neuroscience technology. Good stuff - worth a listen.
MORE: See more on the subject from Baylor Law School's program on Neuroscience and the Law.