Fairness is more than just a dogma, it's an emotion hard-wired in the human brain, claims a new study, which has shown that the brain uses different biological mechanisms for judging a crime and determining its punishment.
The research team led by Owen Jones, a professor of law and biology at Vanderbilt University in Nashville, Tennessee has found that brain assesses guilt and determines punishment through various neural mechanisms in the brain.
Those decisions involve parts of the brain associated with rational thought and emotions.
"It suggests that ancient and modern criminal justice systems may otherwise be built on a much more primitive, pre-existing machinery for recognizing unfairness to you," New Scientist quoted Jones as saying.
Co-researcher Rene Marois suggests that the findings might weaken the central tenet of justice.
"The whole concept that the law represents an uninvolved, decisive, third-party perspective on judging transgression may not be as distinct as perhaps our legal system would like it to be," said Marois.
During the study, the researchers used functional-MRI to analyse the brains of 16 volunteers as they judged scenarios of varying culpability and criminality on a scale of 0 to 9 - from no punishment to extreme punishment.
They found that activity in the right dorsolateral prefrontal cortex (rDLPFC) appeared to play a crucial role in deciding whether or not to punish the criminals on the basis of criminal responsibility.
When the subjects judged obvious homicides, assaults and robberies, their right dorsolateral prefrontal cortexes (rDLPFC) showed more activity than during judgements of crimes where guilt was more ambiguous.
The volunteers were asked to judge clear-cut crimes, ranging from petty larceny to rape and homicide.
They were also made to judge situations where criminal guilt was more ambiguous, for example, a torture and murder directly linked to a brain tumour, or a petty theft in a delusional state.
This region has been implicated in decisions of morality and fairness, as well as other functions unrelated to the law.
Owen then compared the punishment ratings to brain activity, without regard to responsibility.
For instance, a rape and murder committed by a person with a brain tumour and the one wilfully stealing a T-shirt.
They found that the crime committed by a person with a brain tumour might lead to a tougher sentence than the one wilfully stealing a T-shirt.
The researchers claim that activity in several brain areas associated with emotion seems to correspond to the punishment.
More activity in regions such as the amygdala went along with tougher sentences.
"One hypothesis is that it's the emotional regions that are driving the punishment level," said Owens.
He and co reseacher Rene Marois said that their research as a first step in uncovering the neural basis of legal systems and urge trepidation in applying their findings to real-world judges and juries.
The findings appear in journal Neuron.