Neuroscience is changing the meaning of criminal guilt. That might make us more, not less, responsible for our actions.
In the summer of 2008, police arrived at a caravan in the seaside town of Aberporth, west Wales, to arrest Brian Thomas for the murder of his wife. The night before, in a vivid nightmare, Thomas believed he was fighting off an intruder in the caravan – perhaps one of the kids who had been disturbing his sleep by revving motorbikes outside. Instead, he was gradually strangling his wife to death. When he awoke, he made a 999 call, telling the operator he was stunned and horrified by what had happened, and unaware of having committed murder.
Crimes committed by sleeping individuals are mercifully rare. Yet they provide striking examples of the unnerving potential of the human unconscious. In turn, they illuminate how an emerging science of consciousness is poised to have a deep impact upon concepts of responsibility that are central to today’s legal system.
After a short trial, the prosecution withdrew the case against Thomas. Expert witnesses agreed that he suffered from a sleep disorder known as pavor nocturnus, or night terrors, which affects around one per cent of adults and six per cent of children. His nightmares led him to do the unthinkable. We feel a natural sympathy towards Thomas, and jurors at his trial wept at his tragic situation. There is a clear sense in which this action was not the fault of an awake, thinking, sentient individual. But why do we feel this? What is it exactly that makes us think of Thomas not as a murderer but as an innocent man who has lost his wife in terrible circumstances?
Our sympathy can be understood with reference to laws that demarcate a separation between mind and body. A central tenet of the Western legal system is the concept of mens rea, or guilty mind. A necessary element to criminal responsibility is the guilty act — theactus reus. However, it is not enough simply to act: one must also be mentally responsible for acting in a particular way. The common law allows for those who are unable to conform to its requirements due to mental illness: the defence of insanity. It also allows for ‘diminished capacity’ in situations where the individual is deemed unable to form the required intent, or mens rea. Those people are understood to have control of their actions, without intending the criminal outcome. In these cases, the defendant may be found guilty of a lesser crime than murder, such as manslaughter.
In the case of Brian Thomas, the court was persuaded that his sleep disorder amounted to ‘automatism’, a comprehensive defence that denies there was even a guilty act. Automatism is the ultimate negation of both mens rea and actus reus. A successful defence of automatism implies that the accused person had neither awareness of what he was doing, nor any control over his actions. That he was so far removed from conscious awareness that he acted like a runaway machine.
The problem is how to establish if someone lacks a crucial aspect of consciousness when he commits a crime. In Thomas’s case, sleep experts provided evidence that his nightmares were responsible for his wife’s death. But in other cases, establishing lack of awareness has proved more elusive.