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Neurobiology making its way into trial evidence

|Written By Patric Senson

Sometimes real life can be stranger than fiction. Consider the following case: A man is brought into a courthouse accused of committing acts of pedophilia.

There's no doubt he's committed the acts, but everyone agrees the behaviour is totally out of character. Even the accused man is unable to explain the sudden change.

But during consultations with a doctor, a tumour is discovered pressing up against the man's brain, specifically in the region known to be responsible for controlling impulsive behaviour. The tumour is removed, and the sexual urges disappear.

Several years later, the man's behaviour begins to change again, and brain scans show the tumour has grown back. The question for the court then becomes whether the man is truly responsible for his actions, or whether this should be treated as a clinical problem.

  It's exactly these types of cases that have attracted the interest of Dr. Owen Jones, a professor of law and biology at Vanderbilt University in Nashville. As our knowledge of brain structure and function is growing, we're starting to understand more about motivation and both conscious and unconscious responses. We're even learning how to read people's thoughts. This increased understanding of neurobiology means a new type of scientific evidence is starting to enter the courts.

But interpreting that evidence is tricky.

"There is no way you can automatically conclude that the brain tumour was causing his pedophilia, but it certainly raises an interesting and important question about the connections of evidence when we know that that part of the brain is often involved in enabling us to be upstanding, rule-following, self-inhibiting individuals in a free society," says Jones about the above case.

So new fields of research are trying to determine just what doctors can, and can't, say about what's really going on in someone's brain.

One of the areas of research, which will be key to answering legal questions, revolves around understanding the biological basis for emotionally driven behaviours. Is it possible to link brain structures to specific motivations? Which was the key question in the pedophilia case.

Dr. Marc Hauser, a Harvard University psychology professor, has been looking at that question. In a paper published earlier this year, he and colleagues examined patients with damage to the ventral medial prefrontal cortex, an area of the brain known to connect the emotional centres with decision-making regions.

The patients were set two different forms of ethical dilemmas. In some cases, called "moral impersonal," the patients were set, as Hauser puts it, "situations in which an individual would act in a certain way, not making any physical contact with someone else, but the consequences might be very good for many people, but harmful to one person."

The classic example for this is a train with no brakes heading toward five people standing on the track. You can flip a switch and save the five people, but one other person on a siding will be killed; what do you do? Most people willingly flip the switch.

In a second scenario, "moral personal," you can only save the five people by throwing someone onto the tracks. The same outcome, but most of us would balk. Not Hauser's patients. In his experiment, they felt no aversion to sacrificing the one person, even though it would mean acting as the agent of their death.

"For a certain and very narrow class of moral dilemmas that pit the needs of one against the very strong utilitarian outcome of saving the lives of many, the conflict is silenced, allowing the consequence to emerge triumphantly in the decision process. So I think this has some very deep implications," he says.

As we discover more about brain regions that influence our decision-making choices, it will directly impact the legal system.

The question is one of responsibility. As Hauser points out, "The law has to figure out responsibility and, on the simplest cut, the law wants to distinguish between intentional and accidental activity."

As neurobiology identifies areas like the moral centre, it may free up some people from responsibility for their actions.

"We don't say a lion is responsible for his action of killing a gazelle; there is no responsibility there," says Hauser. "I think in each of these cases [of identifying regions associated with moral behaviour], we have to firm up what we mean in terms of responsibility, and biology is going to show us something meaningful in terms of that notion."

Not everyone is convinced the story of moral behaviour and biology will ever be cut and dried though. Dr. Lesley Fellows, an assistant professor in the department of neuroscience and neurology at McGill University in Montreal, also works with patients who suffer from brain damage. These patients often have trouble controlling their behaviour, but, as she says, "It's just the case that most of them are not in jail.

Even with direct injury most of the time, although people's behaviour may change, they generally don't change to the extent of getting them in trouble with the law."

This underlines the key issue around neurobiology and it's place in the courtroom.

As Jones points out: "We've got this intersection of technology that promises to answer some of our questions about where behaviour comes from and why people do what they do. At the same time, we know that there may only be so far we can go back in this causal chain to get at the first moving causes."

At the moment, we have no idea how much we'll be able to explain with neurobiological research.

That hasn't stopped it already appearing in the courts though. Jones has followed the introduction of neurobiological evidence in the United States and says, "What we see here in the U.S. is a large set of cases in which brain scanning information has been introduced. In some cases it's allowed into evidence, in others it's not."

At present, each court is making its own decision on admissibility.

"I would hesitate to call it pandemonium, but we certainly don't have any systematic way of treating the information at present," he says.

This concerns Fellows. She's worried about the "CSI effect," and says, "If we get it into the courts too early, it carries more weight than it should. I don't think the jury will listen when they're presented with the pretty pictures of an angry brain, so I think we have to be particularly cautious about moving that too quickly into the courtroom, even if, assuming as a society, we think that's an appropriate thing to do."

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