01 Nov 2007

Brain scans in court?

It was one of the worst killing rampages in US history. In August 1966, Charles Whitman murdered his wife and his mother, then climbed a tower at the University of Texas and used a high-powered rifle to fatally shoot 14 more people before being killed by police.

He left a note that said, "I cannot rationally pinpoint any specific reason for doing this." An autopsy later revealed he had a brain tumour, which some experts said may have affected his actions.

At the time, there was no way to detect such a tumour without surgery. But today, scientists have developed non-invasive brain scans that may reveal whether a person has a brain abnormality that could affect decision-making or trigger violence, with huge implications for the law.

Neuroscientists use functional magnetic resonance imaging techniques - in which a person's head is put in a machine like a giant magnet - to gaze deep within the brain to view neural regions that monitor behaviour and regulate emotions.

A dramatic impact
It is a young field, but one that ultimately could have as dramatic an impact on the legal system as DNA testing, said Michael Gazzaniga, the director of a new project to study the implications of neuroscience for the US judicial system.

Neuroscience "is all about understanding brain mechanisms that underlie behaviour," said Gazzaniga, who heads the Sage Centre for the Study of the Mind at the University of California in Santa Barbara.

In the Whitman case, it's impossible to know for sure if the tumour led to his actions, but there is now strong scientific evidence that the presence of brain abnormalities "does increase the probability of doing something violent," said Gazzaniga, who is a psychology professor.

Deep challenges
The science, however, poses deep challenges for the legal system, which may confront a flood of criminal defendants armed with brain scanning results who try to argue that they shouldn't be held responsible for crimes.

It also raises complex issues of free will and privacy, such as whether society should try to institutionalise people whose brain scans indicate defects that may predispose them to violence.

"We have to examine very carefully how to use that information in a meaningful way," Gazzaniga said. "Someone who has an abnormal brain function may commit a crime, but there are a lot of people with that same brain lesion that don't engage in criminal activity." The Law and Neuroscience Project, supported by a three-year, $10 million grant from the MacArthur Foundation, has gathered together scientists, legal scholars and philosophers from more than a dozen universities in the US, as well as several judges.

Organisers of the project, whose honorary chair is former US Supreme Court Justice Sandra Day O'Connor, say they will address issues such as when brain-scanning images can be introduced in court and how the prison system should deal with convicted criminals who have brain abnormalities.

Already, courts are seeing more cases in which defendants want to use brain scans as mitigating evidence. In early October, a Florida appeals court rejected arguments by a man convicted of murder and robbery who contended that his lawyer hurt his case by not trying to introduce brain imaging results that the defendant believed would have shown that Ecstasy and other drugs he took hindered his rational thinking.

Is the pain real?
The technology could also transform civil suits, such as when trying to determine whether a car accident victim in a personal injury case is truly still in pain.

"Is there real pain there or is it put on?" Gazzaniga said. It may be possible "to put them in a scanner and see if we can detect pain centres lighting up."

Neuroscience, though, clearly poses challenges for the law, which has traditionally taken a rather clear-cut view of responsibility: people either commit acts intentionally or they do not.

Line getting fuzzier
But as neuroscientists discover more about how our brains affect behaviour, the line between guilt and innocence gets fuzzier, said Jed Rakoff, a US District Judge in New York who sits on the project's board.

"I don't want to overstate the situation, but the long-term implications are that the legal system becomes much more nuanced in the way it evaluates responsibility," he said. "It's not so easy to say an act is either intentional or wasn't intentional. What do you do with an in-between possibility?"

Rakoff, though, said that ushering neuroscience into the courtroom does not mean defendants with brain abnormalities should get a free ride.

He said neuroscience is leading to findings about substance abusers, for example, that suggest the roots of addiction lie within the brain. Treating the problem can require a drug addict to undergo a much longer programme than the inpatient drug programmes that courts now require.

Rakoff said that there is also sure to be "a lot of junk science" that lawyers will attempt to introduce based on neuroscientific findings. A goal of the project, he and others say, will be to give judges guidelines about using the new science.

"We hope that by the end of the three-year period it will be clear that neuroscience can be useful for the law when it is appropriately applied," said MacArthur President Jonathan Fanton. "This is a science that has come along dramatically in recent years and we think if properly used it can make our justice system more fair, compassionate, but also more rational." - (Reuters Health)