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New Research on Detecting Pain

Pain is one of the areas where I have long thought (since at least 2003) neuroscience might contribute substantially to the law.  New research published September 13 in PLoS One furthers the promise of perhaps using neuroimaging to determine who is, and isn’t, in pain – and, maybe, how much.

The article, from the lab of Sean Mackey, a Stanford anesthesiologist (with whom I have collaborated on various things), is available at the PLoS One site.  The researchers used healthy volunteers who, while in an MRI scanner, were subjected to occasional painful (but not harmful) stimuli – a heated (or not heated) metal bar to the skin.  Using fancy statistical methods, they were able with over 80% accuracy to distinguish the scans of people who were getting the painful stimulus from those who were not.  By classing an intermediate 15% as indeterminate, their accuracy on those they did call went up to 85%.

Now, of course, this is still only 85% accuracy. And these are healthy subjects, in a laboratory context, with a controlled and somewhat artificial painful stimulus.  Much work will have to be done – or, at least, much more will need to be proven – before I would be comfortable using this in a courtroom as evidence for (or against), say, chronic back pain.  But there are hundreds of thousands of judicial and administrative ((think of social security disability) cases each year in the United States in which pain is a major feature.  We do not currently have great ways to detect pain and we believe that some successful claimants are exaggerating, or completely faking their pain – and some unsuccessful claimants actually are feeling substantial pain.

In at least two cases I know about, litigants have retained expert witnesses on neuroimaging of pain, though both cases settled before trial.  Adam Kolber, of Brooklyn Law School (and the excellent Neuroethics and Law blog) has written several good pieces about pain, including Pain Detection and the Privacy of Subjective Experience, 33 AM. J. L. & MED. 433 (2007), The Subjective Experience of Punishment, 109 COLUM. L. REV. 182 (2009), and (in part) The Experiential Future of the Law, 60 EMORY L. J. 585 (2011).  And the Center for Law and the Biosciences held a conference on the issue in late 2008, which the authors of the recent PLoS article cite as the inspiration for their research!  (Audio recordings from the conference are here.)

This is going to be an increasingly important field.  Watch this space!

Hank Greely

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