The Scientific Case Against the Death Penalty

Many experts believe that there is enough data to emphatically claim that violent behaviour is, in part, biological.

In early April, Amnesty International reported that India ordered a total of 136 executions in 2016, up by 81% compared to the previous year. It added that by the end of 2016, 104 countries around the world had abolished the death penalty.

Over the years, criminal defence lawyers around the world have argued with varying success that violent behaviour is in part due to biological and genetic vulnerabilities – all in order to decrease the culpability of the individual. The notion that criminal behaviour is the result of biological disposition and partially beyond one’s control has been popular for some time now and extensively researched.

Studies have implicated higher testosterone levels, neurotransmitter abnormalities, an extra Y chromosome and the warrior gene in some men. Others have documented abnormal electrical and metabolic activity in the brains of violent criminals. Some of these ideas continue to attract attention while others have fallen by the way side, and the puzzle remains unsolved. However, many experts, including the world’s leading neuro-criminologist Adrian Raine, believe that there is enough data to emphatically claim that violent behaviour is, in part, biological.

A field that is rapidly evolving and may provide indirect evidence to allow us a better understanding of the biologic basis of aggression is pharmacogenomics. It is the study of how genes affect an individual’s response to drugs.

It is common knowledge that certain medications can induce aggressive behaviours and even physical violence in otherwise non-violent individuals. One example is varenicline, which is used to stop smoking. Several antidepressants can do the same. An anticonvulsant called perampanel can induce violent behaviours and even homicidal ideation often enough for the drug to carry a ‘black box’ warning to highlight these potential effects. Benzodiazepines are a group of tranquilisers that can, in certain individuals, cause a paradoxical reaction in the form agitation and aggression rather than sedation. A group of drugs used to treat Parkinson’s disease can lead to hypersexuality and this has been brought as a defence in sex-crime prosecutions.

What is curious is that not everyone taking these medications experiences the behavioural changes. Recently, studies have been conducted to understand why only some and not all patients on a particular medication experience adverse neuropsychiatric effects such as aggression and agitation. Levetiracetam is an effective anticonvulsant that is popular among neurologists and commonly prescribed as the first line treatment for seizures. Its behavioural side effects, if they do occur, are usually almost immediate and abate as soon as the drug is withdrawn. These adverse effects are more common in children than adults and can lead to them hitting or biting others.

In 2013, a study examined hundreds of individuals with epilepsy on this drug and analysed the impact of genetic variations on an individual’s susceptibility to the effects. The researchers selected polymorphisms of certain genes of interest a priori. They found that individuals with gene variants associated with lower dopaminergic activity had a higher neuropsychiatric side-effect load. Dopamine is a chemical neurotransmitter in the brain. Though further research is needed to reconfirm these findings, the study underscored the effect of our genes on our behaviour.

These arguments are not meant to give credence to biological determinism or scientific racism. Societal, cultural and environmental factors certainly contribute to all human traits. The arguments are also not meant to discount the potential of rehabilitative measures, especially since we know that the brain is plastic. They are not meant to condone violent crime either. The arguments are made merely to highlight that we have sufficient scientific evidence – or at least ample doubt – to absolve the criminal to the extent that the death penalty can hardly ever be justified, even in heinous crimes.

Add to that the statistical evidence that points to the death penalty not being a deterrent for criminals, and it is certainly time for India to abolish this system of retributive justice.

Jay Desai is a neurologist. He tweets @southgujarati.