Rachel Morgan writes: A groundbreaking but contentious trend is sweeping through US courts: the use of brain scan evidence to inform sentencing decisions. Dr Kent Kiehl's pioneering research, which suggests that some individuals are 'programmed' for criminal behaviour due to their brain structure, has been cited in thousands of cases, with potentially life-changing consequences for defendants.
In 2009, Dr Kiehl testified in the trial of serial killer Brian Dugan, arguing that his client's brain scan showed signs of psychopathy. Although Dugan was initially sentenced to death, his sentence was later commuted to life imprisonment. However, the scientific basis for Dr Kiehl's evidence has been disputed by other experts.
A 2019 study reveals that neurological arguments have become increasingly prevalent in US courts, appearing in over 2,800 judicial opinions between 2005 and 2015. The research suggests that approximately 10-12% of murder trials and around 25% of death-penalty trials involve brain-based evidence, while roughly 40% of serious felony cases reference neuroscience-based arguments.
The study acknowledges that the reported figure likely underrepresents the actual frequency of neuroscience-based evidence in US courts. Many of these cases rely on Dr Kiehl's central premise: that some individuals are predisposed to criminal behaviour due to their brain chemistry, rather than any deliberate choice or fault.
While Dr Kiehl's research has had a profound impact on the American justice system, its validity and reliability have been challenged by other scientists. The implications of this trend are far-reaching, with potentially life-altering consequences for defendants who may be wrongly convicted or receive undue leniency based on flawed evidence.