Brain science may help law – but not yet

Neuroscience may have a big impact on the law in the future – for instance in assessing whether it is safe to release a criminal on probation – but for the time being the legal applications should be approached with extreme caution, the Royal Society says.

An investigation by the society, Britain’s national academy of science, concludes that brain research has not reached the stage at which it can provide reliable evidence in criminal or civil proceedings.

“Claims that murderers can be identified by imaging studies of their brains before committing the crime, or that there is a gene for psychopathy or for violent and antisocial behaviour, are completely wide of the mark,” says the society’s report, written by a panel of neuroscientists and legal professionals.

“There’s no doubt neuroscience will provide some startling revelations about human behaviour, but we can’t be allowed to get ahead of ourselves,” said Nicholas Mackintosh of Cambridge university, who chaired the investigation.

“At this point, our priority needs to be making sure that advances in neuroscience that may have impact on the law are communicated properly to professionals . . . so that when it becomes appropriate, neuroscience is used in court to the benefit of all involved.”

The report raises concerns that the age of criminal responsibility – 10 in England – is unreasonably low, though it does not recommend a specific change. “The science suggests that a 10-year-old brain is immature,” said Prof Mackintosh. “Indeed changes in important neural circuits underpinning behaviour continue until at least 20 years of age.”

One commonly cited area in which neuroscience may affect the law is the detection of lying through an fMRI brain scan. But the Royal Society concluded that this would not be reliable for the foreseeable future because “people can be taught countermeasures that will defeat an fMRI lie detector”.

Defence lawyers in the US are introducing evidence from neurological or behavioural genetics in a growing number of cases: for example, to show that a murderer was not fully responsible for his or her actions because a genetic mutation led to psychopathic behaviour. Such evidence was presented in 722 cases in the US between 2004 and 2009, according to the report, and may soon make an appearance in British courts.

But Prof Mackintosh warned: “Having a psychopathic brain is not an absolute defence against any criminal charge. It does not force you to commit violent crime; it just increases the probability that you will do so.”

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