Brain science in American courts: the culpable neurotransmitters.

Purpose: The purpose of this paper is to analyse how novel homicide defences predicated on contemporary neuroscience align with legal insanity. Design/methodology/approach: Doctrinal analysis, systematic investigation of relevant statutes and cases, was used to elucidate how the law of insanity is evolving. Cases represent the first recorded instance of a particular neuroscientific defence. US appellate cases were categorised according to the mechanism of action of neurotransmitter relied upon in court. A case study approach was also used to provide a contextualised understanding of the case outcome in depth. Findings: Findings broadly depict how the employment of expert testimony runs parallel with our contemporary understanding of key neurotransmitters and their function in human behaviour. Generally, medico-legal evidence concerning neuromodulating agents and violent behaviour was inconclusive. However, the outcome of defence strategy may depend on the underlying neurotransmitter involved. Practical implications: This study shows that as more discoveries are made about the neurobiological underpinnings of human behaviour; this new knowledge will continue to seep into the US court system as innovative defence strategies with varying success. Medical and legal practitioners may gauge the success of a defence depending on the neuromodulating agent. Originality/value: Many scholars have focused on the role of neuroimaging as neuroscientific evidence and how it is used is shaping US criminal jurisprudence. To the best of the author's knowledge, no study has incorporated the true origin of neuroscientific evidence as being underpinned by the understanding of neurotransmitters. [ABSTRACT FROM AUTHOR]