Slide of "Defendant's" Damaged Frontal Lobe (Top: Normal, Bottom: Damaged)

The judge sits at the front of the room.  He has a distinguished look, graying at the temples, and a commanding air.  Glasses perched on the tip of his nose, he addresses the room, “The Bailiff will excuse the jury at this time.”  And as he waves his hand dismissively at the jury, the audience breaks out in titters of laughter.

This is not actually a courtroom, and the judge isn’t wearing robes.  Instead, this is room 2 in the San Diego Convention Center and it is this morning’s session, The Brain on Trial: Neuroscience Evidence in the Courtroom, at the AAAS 2010 meeting.  The judge is a real judge, the Honorable Luis A. Rodriguez, from the Superior Court of California in Orange County.  The session however, is not your normal scientific meeting, and boy is it refreshing and eye-opening.

Set up as a mock-trial, the session was designed to examine the increasingly common dilemma of whether evidence such as MRI images, which can be used to see damage in the brain such as lesions or tumors, should be entered into court cases.   Besides the judge, there was also a Defense Attorney, Mr. Robert Knaier, and a Prosecuting Attorney, Mr. Henry Greely, both actual lawyers.  There were also expert witnesses for both sides of the case, Dr. James Brewer for the defense, and Dr. Michael Rafii for the prosecution.

The fictional case was relatively straightforward.  The defendant, Mr. Johnson, was suspected of killing his ex-girlfriend, Ms. Jane Owens, with a heavy skillet in a fit of rage after he discovered she would be moving across town from the building in which they were both tenants.  There were witnesses who saw him go up to her apartment, and who heard them yelling.  Mr. Johnson’s fingerprints were found on the skillet and his DNA under Ms. Owens’ nails.  Straightforward right?  Well maybe not quite.  MRI scans taken of Johnson’s brain revealed that he has a large brain lesion in his frontal lobes, an area of the brain important for impulse control and emotion.  So do the MRI scans indicate that Mr. Johnson could not form an intent to commit murder due to the presence of this lesion?  Should the MRI scans even be entered as evidence in the court at all?  And we, the audience, were the jurors.  As an added bonus, this jury duty wasn’t even compulsory.

The proceedings were riveting.  After the judge dismissed the “jury” at the beginning of the trial (he actually didn’t make us leave, the dismissal was for dramatic effect), he and the lawyers went through the procedures that would be undertaken in a real case to determine if evidence should be admitted for the jury to see.

The lawyers each stated their case, peppered in legalese, then brought up the expert witnesses.  First, Dr. Brewer was sworn in for the defense.

“You hold an MD and PhD in Neuroscience, is that correct?” asked Mr. Knaier for the defense.

“Yes it is,” Dr. Brewer responded.

Then the defense got into the dirty stuff, asking if the theory that lesions to the frontal lobe cause personality changes has been tested.

Dr. Brewer confirmed, speaking clearly, carefully choosing his words, “It extends all the back to 1848,” with the case of Phineas Gage who famously survived being impaled through the head with an iron rod that injured his frontal lobes but suffered dramatic changes in his personality (you can check out his skull and the iron rod at Harvard’s Countway library of medicine where it is on display).

Next up, the prosecution’s witness Dr. Rafii, an aloof, bespectacled man, was sworn in and his credentials affirmed.

“From a lesion in the frontal lobe would you be able to tell if an individual was able to form an intent to commit a crime?” asked Mr. Greely the prosecuting attorney.

Succinctly, without hesitation, Dr. Rafii replied, “No.”

Throughout the proceedings, both sides made important points.  The defense argued that there is precedence on their side.  MRI images have in the past been ruled admissible as evidence.

The defense went on to say that the jury expects to see MRI’s.  “It is as if they consider them more reliable,” continued Mr. Knaier, than just psychological testimony.

To me this is pretty scary, and shows that the public may at times put more trust in science than the science deserves.  It is also a paradox, since similarly complex, technical science (think climate change) can also make the public wary and defensive.  Interestingly, in law, the complexity of the evidence is actually weighed when deciding whether to present it to a jury.  According to the judge, even if the evidence is relevant, this can be outweighed if it is unduly prejudicial or confusing to the jury.  I had no idea this was something that lawyers and judges consider.  However it does highlight the deficiency in science education in the US.

The judge found the evidence admissible, and we the jury eventually found the defendant guilty, although of Murder 2 (not premeditated) instead of Murder 1.  In the process many questions were raised.  Like, how did the defense get the MRI evidence in the first place and why?  Are you depriving defendants who can’t get an MRI?  Mr Greely, who when not playing a Prosecuting Attorney in mock trials, is actually an academic (though certified attorney) who studies these questions, has done research which shows that there have been maybe 30-100 cases with MRI evidence in the state of California over the past 4 years.  There have however been 100,000 felony convictions, so it’s a small number, for now.  Some of these have also been MRI’s of the victim to help show the extent of injury.

One, very enthusiastic audience member pointed out that science can overturn itself as more discoveries are made.  What is thought to be true today is not always thought true tomorrow.   In response Mr. Knaier pointed out that, “The law should and does lag science.”

In the end, many questions were left unanswered, because there were way too many eager people to ask them, and because some questions really couldn’t be answered definitively.  For instance, if a jury does find that a physical brain injury frees someone from responsibility for a crime they did commit, particularly a violent crime, what then?

A version of this post also appears on the ScienceBloggers site where I’m guest blogging for the AAAS conference.  See it here.

The "Players" Left to Right: Dr. Michael Zigmond (Moderator), Mr. Henry Greely (Prosecuter), Mr. Robert Knaier (Defense), Dr. James Brewer (Witness for Defense), Dr. Michael Rafii (Witness for Prosecution), Hon. Luis A. Rodriguez (Judge)