From Bacillus Criminalis to the Legalome: Will Neuromicrobiology Impact 21st Century Criminal Justice?

The idea that gut microbes or a "bacillus of crime" might promote criminal behavior was popularized in the early 20th century. Today, advances in neuromicrobiology and related omics technologies are lending credibility to the idea. In recent cases of dismissal of driving while intoxicated charges, courts in the United States and Europe have acknowledged that gut microbes can manufacture significant amounts of systemically available ethanol, without a defendant's awareness. Indeed, emergent research is raising difficult questions for criminal justice systems that depend on prescientific notions of free moral agency. Evidence demonstrates that gut microbes play a role in neurophysiology, influencing cognition and behaviors. This may lead to justice involvement via involuntary intoxication, aggression, anger, irritability, and antisocial behavior. Herein, we discuss these 'auto-brewery syndrome' court decisions, arguing that they portend a much larger incorporation of neuromicrobiology and multi-omics science within the criminal justice system. The legalome, which refers to the application of gut microbiome and omics sciences in the context of forensic psychiatry/psychology, will likely play an increasing role in 21st century criminal justice. The legalome concept is bolstered by epidemiology, mechanistic bench science, fecal transplant studies, multi-omics and polygenic research, Mendelian randomization work, microbiome signature research, and human intervention trials. However, a more robust body of microbiota-gut-brain axis research is needed, especially through the lens of prevention, intervention, and rehabilitation. With ethical guardrails in place, greater inclusion of at-risk or justice-involved persons in brain science and microbiome research has the potential to transform justice systems for the better.