A defendant’s fMRI brain scan has been used in court for what is believed to be the first time.
Brain scan evidence that the defense claimed shows the defendant’s brain was psychopathic was allowed into the sentencing portion of a murder trial in Chicago, Science reported Monday. Brian Dugan, who had been convicted of the rape and murder of a 10-year old, was sentenced to death, despite the fMRI scans.
“I don’t know of any other cases where fMRI was used in that context,” Stanford professor Hank Greely told Science.
While the possibility of using fMRI data in a variety of contexts, particularly lie detection, has bounced around the margins of the legal system for years, there are almost no documented cases of its actual use. In the 2005 case Roper v. Simmons, the Supreme Court allowed brain scans to be entered as evidence to show that adolescent brains work differently than adult brains.
That’s a far cry, though, from using fMRI to establish the truth of testimony or that specific structures within an individual defendant’s brain are legally relevant.
It’s difficult to tell whether the Dugan case will be a watershed moment in the use of brain scan evidence in court, or if the evidence impacted the decision in this case.
“The penalty phase of a capital case … is a special situation where the law bends over backwards to allow the convicted man to introduce just about any mitigating evidence,” Greely noted.
Earlier this year, Wired.com reported on another attempt to use fMRI evidence in which Greely’s MacArthur Foundation Law and Neuroscience Project was involved. In that case, fMRI evidence was entered into a juvenile sexual abuse case in San Diego, but was withdrawn without being admitted.
The debate over whether or not to use fMRI evidence has several dimensions. The first is whether reliable evidence can be obtained. On that score, fMRI appears to perform well. In a very small number of studies, researchers have identified lying in study subjects with accuracy ranging from 76 percent to over 90 percent (pdf). The real doubts begin to surface about whether the data will be good outside the laboratory in real settings.
“When you build a model based on people in the laboratory, it may or may not be that applicable to someone who has practiced their lie over and over, or someone who has been accused of something,” Elizabeth Phelps, a neuroscientist at New York University told Wired.com in March. “I don’t think that we have any standard of evidence that this data is going to be reliable in the way that the courts should be admitting.”
Even if the data isn’t perfect, some law theorists say it might be on par with traditional lie-detection carried out by human beings, if not better.
“It’s not clear whether or not a somewhat reliable but foolproof fMRI machine is any worse than having a jury look at a witness,” Brooklyn Law School’s Edward Cheng said. “It’s always important to think about what the baseline is. If you want the status quo, fine, but in this case, the status quo might not be all that good.”
Others like Greely argue that until studies are conducted under realistic settings, the technology should stay out of the courtroom.
One thing seems clear: If brain scan data has even a remote change of helping a defendant’s case, defense lawyers will keep to try to enter the evidence into court.
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