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Judges Grapple with Neuroscience Issues
Several hypothetical cases, posed to a group of state and federal judges recently at a seminar organized by AAAS and its partners, offered intriguing questions courts might someday face as a result of future advances in neuroscience.
- Should a white-collar defendant in a corporate fraud case be subjected to a brain scan to determine whether he has ever seen certain incriminating documents?
- Can a scanning procedure that identifies those with a propensity to violence be used to send a newly-convicted felon to a maximum security prison even though he committed a non-violent offense? Should such scans be used to determine a person’s suitability for employment?
- Should testimony by a sharp-eyed witness to a crime be admissible in court if it turns out the witness had been taking a new drug meant to enhance memory?
While predictive scanning procedures are not yet available—and may never be, according to some researchers—recent developments in neuroscience already have been trickling into the legal arena.
Judges have been asked to admit scans and data from existing brain imaging techniques, both in civil and criminal cases, according to O. Carter Snead, an associate professor at the University of Notre Dame law school. He spoke at a 29-30 June “Judicial Seminar on Emerging Issues in Neuroscience” at the Dana Center in Washington, D.C. The seminar, funded by the Dana Foundation, was organized by AAAS’s Scientific Freedom, Responsibility and Law Program in cooperation with the Federal Judicial Center and the National Center for State Courts.
Snead said images from functional magnetic resonance imaging, or fMRI, and other neuroimaging techniques are being admitted in courts, principally in civil trials to help show that a plaintiff has experienced a head injury. In criminal trials, the scans have been used by defense attorneys to try to prove that a client is incompetent to stand trial or acted with diminished capacity. They’ve also been used in sentencing hearings. Snead noted that while such evidence frequently is admitted, especially in the sentencing phase of criminal trials, the success rate is mixed.
In a 2003 case in Iowa, a state court was asked to accept testimony on a “brain fingerprinting” method that analyzed certain brain waves and purported to show that a convicted murderer’s brain did not contain information about the murder but did contain information consistent with his alibi. The court ultimately reviewing the case did not rule on the admissibility of the analysis since it was unnecessary to the resolution of the appeal, according to Snead.
Last year, the Supreme Court, in holding in that the death penalty is prohibited for persons under age 18 at the time of the capital crime, cited evidence from neuroimaging research suggesting that adolescent brains are not fully developed and in some cases not able to support such functions as impulse control and long-term planning.
While neuroscience has been used in the courtroom for limited purposes such as helping demonstrate the results of traumatic brain injury, that is different from trying to use the technologies “to show something about personality, volition, motivation,” said Barbara J. Rothstein, director of the Federal Judicial Center and a Federal District Court judge in Washington state.
Nevertheless, science has been providing an increasingly sophisticated understanding of brain function. Using sensors wired into individual brain cells in animals, researchers have found neurons in particular brain areas that respond selectively to motion, color, faces, objects and places. Damage to specific regions of the brain also has been linked to specific deficits, such as loss of vision, speech or motor control. Researchers also are using brain scans in humans to probe the function of brain regions associated with cognition and impulse control.
The work to date is descriptive rather than predictive, experts say. But as science gains a better understanding of the physical basis in the brain for certain behaviors, some specialists argue that concepts such as free will, competency and legal responsibility may be open to challenge. Against that backdrop, they say, it is important that judges be educated and informed about the scientific status of imaging studies and other neuroscience methods.
One area of obvious interest is the potential for using new brain scanning methods to detect truthfulness. Unlike the polygraph, which seeks to detect lying by monitoring indirect responses such as elevated blood pressure and respiratory activity, faster heart rate and perspiration through the skin, the brain imaging methods such as fMRI seek to directly assess and measure the brain activity that underlies a conscious decision to deceive.
Studies using fMRI, which tracks metabolic activity in the brain, have given hints that several brain regions, including one called the anterior cingulate cortex—which is associated with conflict and cognitive control—are active when a person is lying, according to David Heeger, professor of psychology and neural science at New York University. But the work relies only on correlations. There is no cause-and-effect link between the measured brain activity and lying, he said, and no quantitative theory of lying to explain the data.
“I don’t think that this technology is anywhere near there yet,” Heeger said. But as researchers’ understanding of the brain continues to improve, he said, “it will get closer and closer.” Several companies already are offering fMRI as an alternative to the polygraph for lie detection, a step Heeger and others say is premature and not based on sound science. One federal judge said he would not allow fMRI “lie detector” data into his courtroom based on what he had heard at the judicial seminar.
“It is very unlikely that there is one region in the brain that is a truth detector,” said Daniel Schacter, a Harvard University psychologist and specialist on memory. But he said there is intriguing evidence that parts of the brain do activate more strongly when a person is telling the truth about a remembered object or shape.
Experimenters have the luxury of controlling variables and actually knowing what happened as subjects are presented with a series of objects and later asked to recall them accurately, Schacter said. The real world is a lot messier. He said the fMRI is not a “truth machine” now and is unlikely to be for the foreseeable future.
Another area of intense interest is the possibility that neuroscience might someday be able to predict a person’s propensity for violence or criminal behavior. Monte S. Buchsbaum, professor of psychiatry at Mount Sinai School of Medicine in New York City, told the judges there are centers in the brain that do seem to be associated with aberrant behavior when damaged. Buchsbaum noted the case of a middle-aged businessman with three children who started frequenting online chat rooms for pedophiles after he suffered a stroke in a part of the brain that is associated with cognition and judgment. He eventually was arrested on a pedophile charge. Should the damage to his brain mitigate or excuse his behavior, Buchsbaum asked. If the brain damage is permanent, does that make him a dangerous threat to society?
These are questions you and society will have to wrestle with,” Buchsbaum told the judges. At the same time, he urged caution in trying to attribute complex behaviors to localized damage or abnormalities in brain function. Neuroscience research has shown convincing causal links between certain aspects of cognition and activity in certain brain areas. Buchsbaum cited the link between a part of the brain called MT and the perceived motion of an object. But he said researchers are unlikely to find a comparable center for “grandiosity” or other traits associated with mental disorders such as schizophrenia. Nor is he persuaded that scientists will ever find a clear-cut brain center for violence.
While neuroimaging eventually might provide clues to brain activity associated with an increased risk of aggression, he said, “I don’t think there is a ‘murder’ center sitting there in the frontal lobe.”
Joshua Greene, a Harvard University philosopher, posed the fundamental question of whether bad behavior is caused by something external to the person’s brain—a guilty mind—or whether the action is solely determined by the mechanistic firing of neurons. He mentioned a case study of a man who made sexual advances on his young stepdaughter. He was found to have a tumor in the right frontal lobe of his brain. When the tumor was removed, his pedophilic behavior stopped. When the tumor later recurred, the behavior resumed. Should the man be blamed for his actions or should they be blamed on a “broken brain?”
Greene argues that advances in neuroscience eventually may make the notion of free will an illusion. Neuroscience may never be able to predict a specific action based on a brain scan, he says, but science increasingly will reveal a mechanistic basis to human decision-making. That does not mean that people should be exempt from legal responsibility for their actions, however. The law should deal firmly but mercifully with persons whose behavior is obviously the product of forces beyond their control, Greene said. But the emphasis should be on deterrence and containment rather than retribution.
Whatever the long-term impact of neuroscience on such questions as free will and determinism, judges at the seminar said they found it to be useful in explaining the existing state of the science and how to assess some of the technologies that soon may be commonplace in court proceedings.
“I’ve learned about some techniques I should stay away from,” said William Stafford, a federal judge in the Northern District of Florida. “I’ve learned what I think is reliable and not reliable, lots of red flags and cautionary signals and yield signs as far as evidentiary matters are concerned.” He added, “It’s important that we be cognizant of what is going on and not be overwhelmed by somebody coming in with a whole fancy resume and spouting off a lot of stuff that sounds good, when you know from this program that you ought to be suspect.”
12 July 2006