Accessibility Skip to Global Navigation Skip to Local Navigation Skip to Content Skip to Search Skip to Site Map Menu

Criminal minds

Colin Gavaghan

Rapid advancements in genetics and neuroscience are providing new insights into the minds of criminals. The question now is, how should that information be used?

With genetics and neuroscience now able to delve deeper into a criminal"s neurochemical and genetic make-up, leading legal and ethical minds are grappling with how that information might be used in court.

Director of the New Zealand Law Foundation Centre for Law and Policy in Emerging Technologies Professor Colin Gavaghan says the interface between neuroscience and law is multifaceted, and neurolaw is increasingly seen as a distinct subdiscipline.

"From a legal point of view, the exciting bit – and the slightly scary bit – is when we get into the realms of making determinations about competence and culpability – about blame and responsibility. And, when we get into the realms of predictions, about what people are going to do next."

The law has always recognised a small number of people may not be responsible for what they do, but the onus has always been on their defence to provide psychiatric evidence. However, Gavaghan says neuroscientists now claim they can do better than that and see what is actually going on inside their heads.

"Sometimes they"re finding things structurally aren"t as they should be and that levels of certain neurochemicals aren"t what they should be. The question becomes what do we do with that information? What do we make of that in law?"

One example he uses involves a man becoming sexually predatory as the result of a brain tumour and finding that, once it is removed, his behaviour returns to normal.

"From a legal point of view, the exciting bit – and the slightly scary bit – is when we get into the realms of making determinations about competence and culpability – about blame and responsibility."

"There are two ways you can interpret that. One of them is to say they are clearly not responsible – the tumour is making them behave in that way. The other possibility is that the tumour is giving them appetites they didn"t previously have, but it doesn"t mean they had to act on them," he says.

"So can we automatically assume that this guy should be excused because he has a tumour? What are we to make of that kind of evidence when it comes up?"

Similar questions could be raised when dealing with people with the gene that gives them low levels of the enzyme monoamine oxidase A (MAO-A). There is evidence to suggest that low-levels of MAO-A, coupled with a rough childhood, greatly increase an individual"s chances of being involved in certain kinds of violent behaviour.

"So what do we do with that if it turns out to be true? Do we use it as an excuse – do we say that they are less responsible than the rest of us and somehow mitigate their sentences?"

Gavaghan says there have been two cases in Italy where people who were charged with murder had their sentences reduced, partly due to evidence that they had this low-level MAO-A variant.

"It hasn"t happened in New Zealand, but it is only a matter of time before some enterprising lawyer decides to give it a try." The most likely place it would fit would be sentencing, allowing a judge to have discretion to take that onboard, he says.

With all the rapid advancement in their field, neuroscientists are also saying they can predict, much more objectively and accurately, how a person might behave.

"There is much more of a push towards a 'pre-crime society" – can we get out in front and prevent some of these things from happening?" says Gavaghan.

It is an approach advocated by The Anatomy of Violence author Adrian Raine who has suggested giving all males a brain scan at the age of 18 and, if they show any markers of concern, they could be locked up indefinitely. But Gavaghan says it is a concept that makes lawyers uneasy.

"We"re not talking about punishing people for what they"ve done, we"re talking about treating them on the basis of what we think they might do," he says.

"If we stop it happening in the first place, that"s great, but the obvious danger is how would it feel to be locked up for something you"ve never done and believe in your heart of hearts you would never do?"