Criminal behavior can't be blamed on how someone's brain is wired, at least not yet, says a report from British experts who examined how neuroscience is being used in some court cases.
"Having a psychotic brain is not a general defense against a criminal charge," said Nicholas Mackintosh, emeritus professor of experimental psychology at the University of Cambridge, who led the group that produced the report. "There's no such thing as a gene for violence."
The report was done by the Royal Society, the world's oldest scientific academy. The document is part of the group's ongoing investigation of the effects of recent advances in neuroscience on various parts of society, including education and the law. Another report early next year will look at the potential implications of neuroscience on military and security issues.
After examining the state of neuroscience and how it might apply to the legal system in the U.K., the Royal Society concluded it's too soon for the law to be swayed by scientists' understanding of the brain. Still, brain scans have been cited in an increasing number of cases in the U.S. The authors of the report said they could one day prove useful for matters like parole hearings when trying to predict whether someone will commit another crime.
The scientists said that while some criminals, such as psychopaths, have different brain structures from most people, these differences aren't enough to release them from being legally responsible for their actions.
Some experts said it was too simplistic to think brain scans could explain human actions.
"When we see a brain image, we want to assume a blob correlates to a complex behavior," said Carl Senior, a neuroscience expert at Aston University in Birmingham and a spokesman for the British Psychological Society. Senior was not connected with the Royal Society report.
He said many other factors like a person's upbringing and the circumstances of a particular crime determined whether a crime was committed _ and that a brain scan wouldn't be able to show that.
The report cited data gathered in the U.S. by one expert that suggested the number of cases where neurological or behavioral genetics evidence was used in criminal cases had doubled from about 100 to roughly 200 during the years 2005 to 2009. That information was reported by Nita Farahany, an associate professor of law at Vanderbilt University's law school.
Mackintosh said most of those cases were for defendants on death row. He said neuroscience has not yet been used in British courts and is rarely used elsewhere.
However, he cited a case in Italy, where a woman was convicted of killing her sister and burning the body, and attempting to kill her parents. Her defense team introduced genetic information showing the defendant had brain abnormalities, arguing that she was mentally ill. In August, the court cut the woman's sentence from life in prison to 20 years.
Mackintosh wouldn't comment on whether he thought that was appropriate, except to say that genetic data and brain scans should only be used in exceptional cases.
He also suggested neuroscience might be helpful in determining things like the age of criminal responsibility, which in England is age 10. "The science says a 10-year-old brain is still immature and developing," he said, adding that the brain generally isn't fully developed until age 20.
There has long been a debate in the U.K. about the age of criminal responsibility, provoked in part by the 1993 killing of Liverpool toddler James Bulger by Jon Venables and Robert Thompson, both 10. In 2001, both were released and given new identities, but Venables was later sent back to a prison hospital.
Senior acknowledged it was tempting to look to neuroscience as a possible explanation of criminal activity but that to do so would be a mistake.
"We just know far too little about brain imaging to draw any conclusions right now," he said. "But let's revisit the situation in a couple of decades and see where the evidence stands."