Magnetic Resonance Imaging enters the courtroom
Neuroscience, i.e. the complex of sciences that studies the relationships between brain mechanisms and human behavior, plays a highly topical role at the intersection between science, courtroom and criminal law today. These are complex techniques, which carry a high degree of subjectivity both in implementation and interpretation of the results. They only have a statistical value as they are based on an empirical generalization inductively derived from common experience and detached from the concrete fact that needs to be proved. They are based on theories whose error rate is not always known and in relation to which it is often impossible to implement falsification tests.
These scientific methodologies, increasingly used in US courtrooms but not only, can be distinguished according to their usage. First of all, there are techniques (PET, fMRI) that can evaluate the mental state of the accused because they provide indications of their neurological conditions through the analysis of blood flows to a specific region of the brain. Then, there are lie-detection and memory-detection tools (Brain Finger Printing, the Implicit Association Test, in addition to the aforementioned fMRI) that can contribute to the reconstruction of the fact because they are capable of evaluating the witness's ability to remember. In short, the assumption underlying these studies of the cerebral cortex is that, compared to telling the truth, lying involves quantitatively and qualitatively different mental processes. When we lie, we must inhibit the truthful response and fabricate a false response that we must faithfully repeat every time we are asked the same question. From a cognitive point of view, all this involves a greater “mental effort” that calls into play the mechanisms of attention and memory as well as those of planning, abstract thought and control.
Net of the evident contribution that these techniques can make to ascertain the truth in a crime, the invitation is to navigate these issues with overzealous care. Neuroscientific methodologies, in fact, are able to condition the person's capacity for self-determination and their aptitude to correctly remember and critically evaluate the facts for fear that the possible outcomes of the exploration of the brain could be uncritically assumed as prejudicial, mortifying or stigmatizing elements. From this point of view, the tension is evident between the use of neuroscience and fundamental principles such as respect for moral freedom and the dignity of the human person. Moreover, the protection of human dignity, as derived from the normative paradigm constituted by constitutional and supranational provisions, prevents the transformation of the body and its psychic sphere into an immediate source of evidence that should, instead, emerge through oral debate and interrogation.
The value of the search for judicial truth, although it takes a central position in the constitutional and supranational legal system, cannot, therefore, be considered preeminent with respect to the value constituted by the dignity of the human person and the protection of their sphere of inviolability, with which the former must find a balance. Naturally this depends from the fact we all agree that inducing or forcing a suspect to admit what they would never have freely admitted without violating their psychic intimacy is detrimental to human dignity. And thus we should all agree that it is incompatible with the respect for human dignity to reduce a person and their actions to a series of data to be read in the courtroom, after being automatically processed and coldly elaborated by an expert system, one which is only allegedly capable of explaining the defendant's behavior.