In Jeffrey Rosen's March, 2007 article in the New York Times Magazine "The Brain on the Stand," he writes of the case: "Weinstein's lawyers could tell the jury that brain scans had identified [the] cyst, but they couldn't tell jurors that the cysts were associated with violence. Even so, the prosecution seemed to fear that simply exhibiting images of Weinstein's brain ... would sway the jury. Eleven days later … they agreed to let Weinstein plead guilty in exchange for a reduced charge of manslaughter."
Such conditions can and do lend themselves to leaner sentences. Although impulsive behavior is no excuse in a court of law, Roper v. Simmons in 2005 demonstrated it can hold sway. The famous case ruled it unconstitutional to impose capital punishment for crimes committed by minors and mentally retarded people, as they are in general more compulsive. Impulsivity is not an excusing condition, but physical evidence that reveals such can at times change a death sentence to life.
"Neuroimaging is a knife that cuts both ways," says Stephen Morse, professor of law and psychiatry at the University of Pennsylvania. He says that even if a defense argues a particular neuroimage supported a "behavioral legal-excusing condition," that same evidence might also show that the person is dangerous.
"Legal responsibility criteria are behavioral, including mental states," says Morse. "Only in cases where the behavioral evidence is unclear might neuroscience help us much … and then the question is, is the neuroscience sensitive enough to really help? At present, I just don't think [we have] that degree of scientific precision."
Unearthing the root cause
It's hard to image the thought process of people who flagrantly commit crimes. Violence is brought about by many variables; certainly brain dysfunction alone doesn't mean somebody will participate in this behavior. Dr. Robert Heilbronner, director of the Chicago Neuropsychology Group, is often retained in criminal and capital cases where there's a question of neuropsychological consequences as a result of a number of factors. He reports head injuries are the most prominent of factors, followed by substance abuse, exposure to toxic substances, learning disabilities, etc.
He stresses that violence itself represents a "final common pathway" that arises from a combination of things, often including brain dysfunction in the context of other environmental determinants, such as socioeconomic pressures, how someone responds to provocation and role modeling he or she has had throughout life.
In some cases a perfect storm exists where environmental instigators and preexisting brain problems combine to make way for explosive behavior. Hartman agrees that sometimes "the severity of a brain lesion in and of itself is enough to make someone incapable of controlling their behavior in almost any circumstance."
Most serial killers are not brain-damaged. In fact, the opposite seems to be true. Ted Bundy and John Wayne Gacy were clever psychopaths — intelligent and personable — with specific goals in mind.
"Stalkers and plotters very rarely are brain-injured," says Hartman. "By virtue of the fact that they're able to engage in highly organized behavior, to select their victims and choose the nature and time of a murder, you're dealing with someone [with] very well-controlled brain function.
"I think certainly there are some subtle chemical or wiring differences between murdering psychopaths and normal individuals, but the law [is] very clear that it doesn't care."
Proceed with caution
As many crimes are crimes of passion, most jail residents do not have tumors or cysts that might arbitrarily shut off frontal lobe function. Still, law enforcement has a difficult job whenever they confront an individual.
"I think if officers did [have a clinical history available to them] they would certainly be more careful with individuals who had brain and/or a psychiatric disorder that left them in less control of themselves. But [they] already know that," says Hartman. "They know that there are people you've got to be very careful with." Indeed, common intoxicants like alcohol sedate the frontal lobe, while cocaine can stimulate anger and paranoid thinking. Officers encounter these situations every day.