Can brain scans get defendants off the hook?

http://www.msnbc.msn.com/id/23451536/

New research is using brain scans to show mental illness in defendants in court. "Brain scans have emerged as potentially powerful tools in battles over defendants' sanity. More defense attorneys are seeking scans showing brain damage or abnormalities that might have made it difficult for their clients to control violent impulses." They even say that in the future, brain scans may be able to be used as lie dectors in court. They are concerned that jurors and many in the courts may not be ready to the high tech uses that the brain scan could be used for, but they are very confident that soon it will be very helpful.