our legal system? Brain-scanning
technology is redefining criminal
February 23, 2010
A Mind of Crime
How brain-scanning technology is redefining criminal culpability.
By Michael Haederle
ent Kiehl, a prominent neuroscientist hired to study an admitted murderer named Brian
Dugan, had already been under cross-examination in the hushed, wood-paneled suburban
Chicago courtroom for more than an hour when a brain diagram, hatched with X’s, was
projected on a screen. The X’s marked areas where Kiehl had discovered abnormally low grey
matter density in Dugan’s brain. In a curious meeting of law and neuroscience, those X’s
would help jurors decide whether he should be executed or sentenced to life in prison. Did the
way Dugan’s brain had developed leave him spring-loaded for violence? Or had he chosen
freely when he abducted, raped and killed a 10-year-old girl in 1983?
Defense attorneys had brought in Kiehl and other experts to prove that Dugan was a
psychopath incapable of experiencing normal emotions like remorse, in hopes the jury could
be persuaded to sentence him to life in prison, rather than death.
Kiehl has interviewed and used new technologies to
scan the brains of more imprisoned criminals than anyone else in the world. Here, he was asking jurors to accept that the brains of some
criminals are simply different from the norm and that those differences should be considered during sentencing. “There are abnormalities in his
brain function,” the tall, broad-shouldered Kiehl told the jury. Psychopaths make choices, he acknowledged, but “those choices are not
necessarily informed by emotion in the same way ours are.”
The hearing last fall marked the first time Kiehl, an expert in functional magnetic resonance imaging brain scans, had testified in court, and his
presentation may well have been the first time fMRI had been used in this way. It was also a classic example of the conflicts that arise when law
and neuroscience — disciplines that make competing claims about human nature — intersect, as they increasingly do.
he law sees people essentially as rational actors, capable of forming intentions, weighing the consequences of their actions and controlling
their behavior. As old as civilization itself, the law is inherently conservative, circumscribed by rules and precedent, and rooted in ancient
notions of morality and justice. The law is clear: Those who break the rules we have collectively agreed upon make a choice, and those poor
choices should be punished. Change in the law usually comes slowly and incrementally, in an orderly interplay of legislation and appellate
decision-making that may embrace changing social and scientific norms long after they have gained currency elsewhere.
Neuroscience, on the other hand, is a runaway train of change. Armed with high-tech investigative tools like fMRI, diffusion tensor studies and