However, there is still a fair amount of controversy over whether these techniques are reliable enough to be used in a legal setting . Some studies indicate that while there is an overall positive correlation, there is a great deal of variation between findings and in some cases considerable difficulty in replicating the findings. A federal magistrate judge in Tennessee prohibited fMRI evidence to back up a defendant's claim of telling the truth, on the grounds that such scans do not measure up to the legal standard of scientific evidence.. Most researchers agree that the ability of fMRI to detect deception in a real life setting has not been established.