From Wired Science: "Lie-Detection Brain Scan Could Be Used in Court for First Time"--
A Brooklyn attorney hopes to break new ground this week when he offers a brain scan as evidence that a key witness in a civil trial is telling the truth, Wired.com has learned.
If the fMRI scan is admitted, it would be a legal first in the United States and could have major consequences for the future of neuroscience in court.
It seems unlikely such a scan would be admissible. There are still plenty of low-tech methods of exposing liars, however--see this article at Psychology Today: "Top 10 Secrets of Effective Liars."