On Tuesday the Royal Society published a report called 'Brainwaves and the Law' into how developments in neuroscience may integrate into the legal system. Professor Nicholas Mackintosh of Cambridge University who headed up the report appeared on the BBC's Today #programme on Tuesday morning. From the outset he was keen to stress the limits of neruoscientific research when dealing with questions of social policy.
Such modesty in neuroscience is unusual today: neuroscientists will often talk of the impending demolition job that their tradition is about to undertake on just about all of society's ideas, including punishment, law and order and human agency (see for example David Eagleman's hysterical Incognito). At a time when many in the neuroscientific community are claiming that all and everything can be reduced to old grey matter, Mackintosh and his team have thankfully emphasised that science does not have all the answers.
However, the report did point out the concern of many in the neuroscientific field that the age of criminal responsibility was 'unreasonably low', arguing that the law should be reviewed in light of new evidence.
The report explains that the prefrontal cortex, which is responsible for decision making and judgement is slowest to mature. On the other hand, the amygdala which is responsible for reward and emotional processing develops during adolescence. This may go some way to explaining why teenagers, on the whole, think mostly about themselves and do things which they later realise to be stupid: forming bands, robbing banks etc. The report concludes that 'an arbitrary cut-off age may not be justifiable' given the great variance in relevant brain development among different defendants.
Whilst the report is sensibly timid about its own conclusions, I think it is worth emphasising a central point: neuroscience can tell us very little indeed about whether a person should be held criminally responsible - in legal terms whether they are innocent or guilty. Neither should it have too great an influence on the age at which people are described as 'criminals'. This is because question of innocence or guilt goes is far more complex than merely establishing whether someone behaved in a certain way or their reasons for doing so.
A verdict of 'guilty' means that not only has the jury found that a person has broken the law, but also that they have wronged society to the extent that they are deserving of punishment. This question is often involves drawing fine moral distinctions between legally similar acts: did the person respond reasonably to the situation they were faced with? Were they acting under pressures which absolve them of moral responsibility? This is why jurors have the power to acquit anyone that they choose even in the face of overwhelming evidence. Neuroscience may be able to explain certain aspects of individual behaviour but it has nothing, in and of itself, to say about the inherently social concepts of guilt and innocence.
I think most people still feel uneasy when they see children and teenagers on trial; this has nothing to do with the development of young brains. The unease comes from recognising that growing up involves doing things we later don't understand, getting involved in situations we don't mean to and often making painful and stupid mistakes which do not deserve the condemnation inherent in a verdict of 'guilty'. If we are to make a strong argument for raising the age of criminal responsibility, which I think we should, we will have to look beyond neuroscience and reassert what is important about adult maturity and experience in determinations of criminal guilt.