Brain and the Bar: How Neuroscience Plays out in the Courtroom
Sukriti Ojha '27
Legal statutes outline numerous aspects of performing, executing, and enforcing the law, and legal proceedings are limited to these frameworks to produce an unbiased conclusion. In contrast to the exactness of law, the field of psychology is greatly subjective, particularly in the context of neuroscience and brain research. While studies are continuously conducted in neuroscience, breakthroughs are rare. Moreover, as with any scientific field, commonly accepted knowledge is often disproven as further research is conducted. These aspects of neuroscientific research pose significant challenges and may result in skewed legal decision-making. This article comments on the need for the law to be systemized for an unbiased representation of neuroscientific evidence. It also attempts to analyze why such standardization may be challenging.
There are several reasons for the scarce conclusions that can be drawn from neuroscientific research. Primarily, many discoveries surrounding the brain occur through brain injuries, which cannot be inflicted on patients or replicated for a study. Thus, there are still many unknowns regarding several brain regions, such as how they function and how individualized or coordinated their responses are across regions. Moreover, every discovery made is also vulnerable to being disproved as more research is conducted. Given these reasons, neuroscientific evidence is challenging to work with, especially in a court of law.
There are several case examples where defendants in legal cases used neuroscientific evidence to claim psychological defects. The most famous example of this is United States v. Hinckley. On March 30, 1981, John Hinckley Jr. attempted to assassinate then-president Ronald Reagan in the hopes of impressing actress Jodie Foster. (1) In the trial that followed, Hinckley’s attorneys put forth an “insanity defense,” presenting brain scans that showed wider than normal sulci, which are often associated with schizophrenia. The jury ultimately found Hinckley not guilty on the grounds of insanity. The judgment at the time caused widespread public outrage with rightful concerns about Hinckley not being penalized adequately, given the severity of his crime. Hinckley was eventually placed in a mental facility. Several reforms followed the Hinckley trial, including legislation passed in 1984 that now requires a defendant to prove the insanity defense leaving them incapable of being aware of the nature and consequence of their actions.
There are multiple factors to consider with neuroscientific evidence, including background information such as childhood circumstances or behavioral disorders that influence the defendant’s judgment. Once such factors are identified, it is important to check the extent, if any, to which they may influence the facts of the case. Two cases illustrate this idea, one where background factors were given little importance and another where they significantly influenced the sentencing.
In Vialva v. Watson, Christopher Valva was sentenced to death for the charge of several murders in 1999. (2) Valva later appealed on the grounds that his counsel provided him insufficient assistance and failed to provide evidence about his troubled childhood, including symptoms of bipolar disorder, ADHD, and depression. Among other accusations, he contested that the counsel did an inadequate investigation of his mental ability. Valva’s appeal was entertained. However, the United States Court of Appeals argued that there were no legal grounds to deem the sentencing unconstitutional. Vialva was scheduled for execution by the federal government on September 24, 2020. The above example shows how the evidence presented in the immediate trial may not consider all background factors, and even if it does, there is no requirement to take these factors as causally related and influential. It eventually rests, as it did in this case, on the discretion of the deciding body of how they consider such appeals. Such matters are often discretionary and not standardized.
In another case, United States v. Fields, Edward Fields pled guilty in court to several counts of murder and use of firearms. (3) Fields was sentenced to death and several other terms of imprisonment. In a post-conviction appeal, Fields argued that his counsel did not sufficiently investigate and show the presence of brain damage. Fields contested that this lack of investigation failed to present the damage's effect on his behavior to the jury. In 2011, Fields was allowed an MRI, but it failed to show any damage to his frontal lobe. Nevertheless, the court believed brain damage could be detected in neuro-physical testing, which could not have been seen in an MRI. While in the previous case, the court did not find reasonable grounds to support the appeal, in an almost similar scenario, this court did consider the possibility of a lack of evidence. This shows the disparity in how cases involving neuroscientific evidence are approached and how there is an inherent ambiguity in how such scenarios are dealt with.
One of the flaws of using scientific evidence in law is that the interpretation often fails to distinguish between token and type-level causation. Here, ‘token’ is an example of the ‘type’ or category. For example, “Lufthansa” is a token of the type “airlines.” In terms of causation, if a particular cause is proven to apply to a type of effect, it does not consequently establish that every “token” or case of that effect is out of that particular established cause. Scientific studies are carried out on a pool of participants after standardizing several conditions and making dedicated efforts to remove significant biases. The results produced thus apply to a general population and are only deemed significant in a general sense. Such results cannot be used to testify to the cause of a particular disorder in a particular individual. The fact that a particular condition leads to a disorder does not mean it leads to that disorder in every case. For example, there is evidence that wider than normal sulci are suggestive of schizophrenia. However, it cannot be stated with utmost certainty that the latter caused the former in every case of the disorder. This raises the question of how established medical theories about psychological conditions may be interpreted by a jury. There is a possibility that type-level causation may be mistaken for token level and used to interpret a crime.
In a study conducted by Shelley Batts with “mock jurors,” she found that the jury was more likely to give a verdict in the opponent's favor if any evidence attesting to a brain abnormality was presented. (4) Scientific experiments are often a reliable method of testing hypotheses and drawing inferences and significant weight is attributed to them in various aspects of academic and social science studies. Consequently, when faced with cases where neuroscientific evidence is presented, the jury may be significantly – and sometimes even unjustly – influenced. It is easy to overlook this evidence's inherent bias, as it makes an individualistic assumption about something that is only generally applicable. The law needs to be more systematic than this; neuroscience evidence cannot be loosely presented. There need to be clear standards for when neuroscientific evidence is applicable to a case. Even then, such a presentation must be accompanied by a clear disclaimer stating how this could influence the jury wrongly and unjustifiably. The jury should be made aware of the token and type level distinction, and if such evidence is to be presented, the law must develop clear steps for an unbiased interpretation of such evidence. While the reforms with the Hinckley case are a step in the right direction, there is still a long way to go, both in law and neuroscientific research.
Endnotes
1 Douglas Linder, “The Trial of John W. Hinckley, Jr..” (Social Science Research Network, 2007).
2 Vialva v. Watson, No. 20-2710 (7th Cir. 2020).
3 United States v. Fields, No. 17-7031 (10th Cir. 2019).
4 Shelley Batts, “Brain lesions and their implications in criminal responsibility.” (Behavioral Sciences & the Law vol. 27, 2009).
