© The Author(s) 2016
Chris WillmottBiological Determinism, Free Will and Moral ResponsibilitySpringerBriefs in Ethics10.1007/978-3-319-30391-8_44. Use of Genetic and Neuroscientific Evidence in Criminal Cases: A Brief History of “Neurolaw”
(1)
Department of Molecular and Cell Biology, University of Leicester, Leicester, LE1 9HN, UK
Abstract
As scientific understanding of behavioural genetics and brain physiology have increased, so too have attempts to utilise this information in criminal cases. Defendants in a growing number of jurisdictions have sought the influence of such factors upon a favourable outcome for their trials or a reduction in the subsequent sentence received. This chapter reviews some of the most prominent international cases in which attempts have been made to introduce genetic or brain imaging evidence into criminal proceedings. The majority have taken place in the USA, which seems to have been quicker to allow consideration of this kind of evidence within the legal system. A willingness to reflect on the merits of evidence of this kind does not necessarily translate into a willingness to let it influence the decisions made. To date, there remain relatively few examples where neuroscientific evidence has had a significant impact on the outcome of the case, but there have been some, and their number is growing.
Keywords
DaubertDeath penaltyFitness to pleadFryeGenetic predispositionIneffective assistance of counselLife without parole MAOA Neurolaw4.1 The Emergence of Neurolaw in the USA and Beyond
When J. Sherrod Taylor used the term “neurolaw” to describe the expert testimony offered by neurologists to substantiate brain damage in personal injury trials, he can have had little notion that 25 years later Neurolaw would become a field of scholarly endeavour in its own right (Taylor et al. 1991; discussed by Erickson 2010). Although there remain relatively few examples of neuroscientific or behavioural genetic evidence playing a determining role in criminal cases, there is no doubt that such applications are on the increase. The USA appears to have travelled considerably further down this route than most countries. A comprehensive database of American cases, maintained by Professor Nita Farahany at Duke University, shows that between 2005 and 2012 over 1500 judicial opinions discussed the use of neuroscience by criminal defendants (Bioethics Commission 2015).
This chapter is not the place for an exhaustive review of all case law and attitudes regarding genetic and neuroscientific evidence in disparate countries [readers interested in a recent survey on the latter are directed towards International neurolaw: a comparative analysis (Spranger 2012)]. Instead illustrative cases will be drawn from a variety of jurisdictions where relevant. Given the greater use of behaviour-related science in their legal systems, emphasis will inevitably be placed on examples from the USA.
In some senses America is an atypical setting; it is peculiar amongst Western democracies in retaining the death penalty in the majority of states (which, as we shall see below, does have a bearing on some of the applications of brain and behaviour-related evidence). The USA also has a history of tying itself in knots reconciling the admissibility of a range of potential evidence in courts with the Fourth Amendment (the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures) and especially the self-incrimination clause of the Fifth Amendment (the right not to be a witness against oneself in any criminal case).
This latter conundrum is well rehearsed by Farahany (2012) where she reflects on the existing dilemmas regarding the appropriate handling of evidence as diverse as personal papers, unsolicited comments, DNA samples, and blood-alcohol levels, even before the additional quandaries emerging from the introduction of novel neuroscience. Farahany advocates replacing the existing and problematic classification of evidence as either “physical” (admissible despite the Fifth Amendment) or “testimony” (excused under the Fifth Amendment) with a spectrum of “identifying”, “automatic”, “memorialised” and “uttered” evidence. Since, however, our present focus is on prior cases, this as-yet-untested new model will not be discussed here in any more detail.
4.2 The Place of Scientific Evidence in Criminal Trials
Before we do move on to examine particular cases, it is valuable to lay a certain amount of groundwork regarding the stages of a criminal proceeding at which genetics and neuroevidence might play a part, and to consider more generally the necessary standards regarding scientific evidence and the role of expert witnesses within that process. Reflections on the appropriateness of these applications, and potential future uses of such technologies, will largely be the remit of Chap. 5.
In principal, scientific evidence, including genetic and neuroscientific data, might be presented before, during or after a criminal trial. Evidence could, for example, be presented at a pre-trial competency hearing to ascertain whether a defendant is “fit to plead” at the forthcoming trial. Evidence offered at the trial itself will be used to support or refute the establishment of liability, i.e. guilt for the charges presented. If found guilty, scientific evidence might be introduced at the sentencing phases to help determine the appropriate punishment for the crime. Finally, scientific evidence might again be considered should either side feel there is sufficient reason to launch an appeal against the findings of an earlier trial.
Complex evidence of the kinds described here will, in the majority of cases, be presented by an expert witness. In US federal courts and most state courts it is therefore likely to be subject to Federal Rules of Evidence 702 on the admissibility of expert testimony. These guidelines are often referred to as the “Daubert standard” in light of opinion in a pivotal 1993 Supreme Court case Daubert v Merrell Dow Pharmaceuticals,1 which prompted significant revision to an earlier version of Rule 702. The current (2011) incarnation of the rule states that a witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if: (1) the expert’s scientific, technical, or other specialised knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (2) the testimony is based on sufficient facts or data; (3) the testimony is the product of reliable principles and methods; and (4) the expert has reliably applied the principles and methods to the facts of the case (Legal Information Institute, undated). The rule grants a “gatekeeper” role to the trial judge, to try to avoid the presentation of “pseudoscience” and as-yet-unproven science before a jury. This is acknowledged to be a balancing act, since the latter may, at a subsequent time, come to be accepted as the norm within the scientific community.
Some states have never formally adopted any version of Federal Rule 702 or Daubert, and instead rely on the much earlier case of Frye, or their own state test derived from Frye. Concerning the validity of scientific evidence and related testimony, opinion in Frye stated that this “must be sufficiently established to have gained general acceptance in the particular field in which it belongs”.2
In the UK, expert witnesses are distinguished by their knowledge or experience of a particular field or discipline beyond that to be expected of a layperson. The most significant difference in function for the court, relative to other witnesses, is that experts are allowed to offer opinion, whereas lay witnesses are only allowed to proffer evidence of fact.
4.3 Genetics Factors
Although the linking of identified genotypes to behaviour is relatively new (see Sect. 3.2.3) and cases citing a specified gene have, thus far, been extremely rare, appeals to “genetic predisposition” evidenced by family history have become more common, especially in America.
Over a series of three studies, Deborah Denno, Professor of Law at Fordham University, has conducted careful analysis of US criminal cases in which behavioural genetic evidence has been offered (Denno 2006, 2009 and 2011). In the 17-year from 1994 to July 2011, a total of 81 cases citing evidence of this kind were documented in legal databases.3 Over the course of this period it appears that American courts have become much more willing to accept inclusion of behavioural genetics arguments, especially at the sentencing phase and, even more so, on appeal. Although generally true, this statement does, however, require two important caveats.
Firstly, a distinction needs to be drawn between a willingness to accept genetic evidence as being admissible for consideration by the court, and a willingness to be persuaded by such evidence in the determination of legal decisions. Greater inclusion of behavioural genetic evidence does not mean that judges will de facto allow it to influence judgements in the manner a defendant might hope.
Secondly, although it does appear that in the recent past judges have been more willing to allow genetic predisposition to be grounds for vacating death sentences, this will not necessarily remain so. Indeed, there is already evidence that ramifications precipitated by Cullen v Pinholster (2011)4 may be reversing this trend.
Scott Pinholster: Scott Pinholster’s dealings with the judicial system were long and complicated, and not all of the twists and turns are pertinent to our present discussion. The ‘short version’ goes as follows. Back in 1984, Pinholster was sentenced to death in a California state court for murder. There followed a protracted series of appeals in which Pinholster argued that there had been inadequate consideration of potential mitigating evidence during the sentencing phase of his initial trial. Eventually a Federal District Court awarded Pinholster the right to a fresh hearing, at which significant additional information regarding both his family history, and evidence of the defendant’s brain injuries, were presented. The court granted Pinholster federal habeas5 relief.
At the behest of Cullen, Warden of the San Quentin jail, the Supreme Court reconsidered Pinholster’s case. They agreed with him that the US Antiterrorism and Effective Death Penalty Act of 1996 prevents federal courts from considering habeas petitions based on facts that were available, but were not presented, during consideration at state courts. Accordingly, they reversed the earlier decision.
The reason this is relevant in the current context is not the quality of the genetic and neuroscientific evidence in the Pinholster case per se; these were not really discussed. The importance of the case stems from the more general questioning of the legitimacy of federal courts to introduce fresh evidence when reconsidering state court cases. This, Denno (2011) argues, is already having an impact on the capacity of defendants to introduce additional evidence, including family history and behavioural genetics evidence, at later trials.
In acknowledging this second caveat, we have, however, jumped to reflection on present and future restrictions regarding the introduction of genetic and neuroscientific material. Let us turn instead to a potted history of the evolution of the use of evidence of this kind in earlier trials.
Two landmark US cases involving behavioural genetic evidence occurred in the mid-1990s. In the first, Stephen Mobley made an early bid to introduce molecular evidence emerging from contemporary genetics. We will consider Mobley 6 in more detail in Sect. 4.3.1 below, alongside other cases where attempts have been made to proffer DNA-based evidence. It is worth noting in passing, however, that in this instance the court found his molecular genetic evidence inadmissible; Mobley was found guilty and ultimately executed.
Susan Smith: The second important case concerned Susan Smith. In 1995, Smith was tried in South Carolina for the murder of her children, who drowned when the car in which they were securely buckled rolled into a lake. Both sides were in agreement that this was no accident. The defence argued that Smith was suicidal because her husband discovered she had been involved sexually with both his boss Cary Findlay, and Findlay’s son Tom, and was going to expose her to public disgrace over the affairs. Prosecutors argued that Smith had wanted the children out of the way in order to secure a long-term relationship with Tom Findlay, who was on record as saying he was interested in a future with her, but not one involving her children (Denno 2011).
Central to the defence case was the suggestion that Susan Smith had a genetic predisposition to depression. They presented the court with a genogram, a pedigree diagram in which family members who demonstrated mental instability had been highlighted. Around this, the defence built a fuller picture of Smith’s own history of depression and previous suicide attempts. Closing arguments included reference to “her blood line and her genetic inheritance”.7
This strategy proved partially successful; it did not stop Smith being found guilty of the crime, but she was given a 30-year prison sentence rather than the death penalty which was an option available to the court. In subsequent interviews, several jurors indicated that the family history had been prominent in their decision not to recommend execution.
The sparing of Susan Smith represents an unusual success amongst early (in this context, pre-2004) cases (Denno 2006). This may be a consequence of the fact that, at that time, reference to “genetic predisposition” or similar was often made only in passing. In other instances appeals to genetic causes were little more than a proxy for “a family history” of mental illness/alcoholism/depression/etc,8 without the degree of elaboration exhibited by Smith’s defence team. In one case the fact a defendant’s step-siblings, brought up in the same abusive environment, did not share his inclinations to violent behaviour was offered (unsuccessfully) as evidence of an underlying genetic cause.9 In another, expert witnesses clashed over whether or not the defendant had physical features that may have been typical of a genetic disorder.10 In a further case, genetic evidence was considered inadmissible because the court did not believe the social worker advocating genetic explanations for the defendant’s alcoholism had sufficient expertise in the field.11
Over time, however, there has been a shift to greater willingness to countenance genetic evidence, particularly at the sentencing phase. As Denno (2011: pp. 973–974) notes: “The question now is not whether courts will accept behavioural genetic factors (they overwhelmingly do), but rather what role those factors will play in particular cases in the context of mitigation evidence”.
In her more recent survey, covering the period June 2007 to July 2011, a total of 33 cases involving behavioural genetics evidence were identified. With one exception, these cases all involved defendants who had been convicted and given a death sentence.12 In 26 of the cases the defendants’ grounds for reconsideration included claims of “ineffective assistance of counsel”.13 In 15 cases, genetics was cited to help substantiate diagnosis of a mitigating condition such as addiction to substance abuse or mental illness. In 10 of the cases, i.e. just under a third, appeal successfully led to the vacating of a death sentence.
4.3.1 Molecular Genetics in Criminal Cases
It has been noted many times (e.g. Greely 2011; Walsh and Bolen 2012) that one gene is expressed far more frequently in prisoners than in the general population. The gene in question SRY (for Sex-determining Region Y) is located on the Y chromosome, the ‘male’ chromosome. The reason that it is found expressed in the majority of prisoners is simply a reflection of the fact that most inmates around the world are men. In one sense, therefore, expression of SRY correlates with criminal behaviour. However, no-one would seriously advocate that possession of a Y chromosome is sufficient to cause criminality (not least because the majority of men retain the capacity not to indulge in criminal activity).
I mention this here, because attempts to use as mitigation possession of the less common XYY genome, where someone has an additional copy of the Y chromosome, have been made. In their review of US case law, Farahany and Coleman (2006) record that on several occasions during the 1960s and 1970s (and as recently as 2003), defendants have attempted to introduce their XYY karyotype as grounds for the insanity that led to their behaviour. Only once, in People v Farley,14 did this argument get as far as consideration before a US jury; they rejected it. In an Australian case of 1968, Lawrence Hannell15 was acquitted of the murder of a 77 year old landlady. Hannell was found to be XYY, but he was clearly insane according to other M’Naghten criteria (Sect. 2.1.2) and his extra Y chromosome is not considered to have been a significant factor in the decision to acquit him by reason of insanity (Denno 1996). In a French case that same year, the court permitted evidence of an XYY genotype as mitigation when sentencing Daniel Hugon for the murder of a prostitute (Iofrida et al. 2014).
Regarding the use of molecular biology in criminal law, it is important to pick out a number of particular cases where defendants have tried to invoke their MAOA genotype. As discussed in Sect. 3.2, monoamine oxidase, the product of the MAOA gene, is needed by the body to switch off certain neurotransmitters. In combination with inappropriate childhood stimuli, mutations leading to low level of expression of the gene have been implicated in aggressive behaviour. Each of the cases where the defendant’s MAOA genotype was cited will be considered in turn.
Stephen Mobley: As noted above, the first attempt to use molecular genetics as mitigating evidence came in the 1994 case of Stephen Mobley.16 In 1991, Mobley killed the manager of a pizza franchise in Georgia. Following an initial guilty verdict Mobley was sentenced to death. At a Direct Appeal, his defence team requested that their client be allowed to have a genetic test to see if he carried the monoamine oxidase A (MAOA) gene mutation which had recently been identified as a factor in the aggressive behaviour of a Dutch family (see Sect. 3.2.3). The judge decided that the courts were not yet ready to consider evidence of this kind and declined their request. Mobley was executed in March 2005 (Eastman and Campbell 2006).
Although Mobley was unsuccessful in his attempt to introduce evidence of a genetic predisposition to aggression, two further cases, both in 2009, saw MAOA genotyping used in the courtroom to influence the outcome of trials.
Abdelmalek Bayout: In Italy, Algerian-born Abdelmalek Bayout stood trial for killing another man. Having been verbally abused and then beaten up by a group of young men, Bayout went to a cultural centre and changed clothes, before buying a knife. He set out in pursuit of his attackers, but wrongly identified a man who shared their ethnic background and stabbed him to death (Baum 2013).
At his initial trial, the judge took into account several aspects of mitigation, including the defendant’s history of schizophrenia and the fact that he had stopped taking his medication some six months before the crime was committed. The judge deemed these to be grounds for diminished responsibility, but not insanity, and so reduced the sentence to nine years (rather than the usual twelve years). If this was not already sufficiently controversial, it was at the subsequent appeal that genetic evidence was introduced. The defence reported that Bayout possessed the MAOA–L allele, encoding a low-activity variant of the enzyme. In light of this additional information, the judge reduced the sentence by a further year, to eight in total (Feresin 2009).
In the current context, there are several important points to note about the Bayout case. Firstly, should failure to take appropriate medication to counter a known medical condition be grounds for reducing a sentence? It might even be argued that this wilful neglect ought to see a sentence increased. Secondly, although Bayout had the MAOA–L genotype, there was no documented evidence of abuse during childhood (which is considered to be a crucial factor alongside possessions of the relevant allele in the development of aggressive behaviour). Instead, the pertinent environmental influence was taken to be his move from Algeria to Italy at the age of 24 which, it was alleged, led to culture shock and loneliness. Thirdly, there had been a delay of more than one and a half hours between the initial assault and the vengeful murder. This is a longer period between trigger and response than would be usual for impulsive-reactive violence as seen more typically with MAOA cases (Baum 2013). Fourthly, in keeping with most of the cases discussed above, the genetic evidence came into play during sentencing, i.e. post-conviction, as a mitigating factor.
Bradley Waldroup: In the other case from 2009, this time in Tennessee, testing for the MAOA status of the defendant had an even greater role. During an argument with his estranged wife and her female friend, Waldroup took out his rifle and killed the friend (with whom he believed his wife had been involved sexually). As his wife tried to escape, he shot her in the back and then set about her with other weapons including a knife, a spade and a machete. At this point the police intervened and the wife, though severely injured, was saved.
As with Bayout, MAOA evidence was used at Waldroup’s trial, but there are several important distinctions between the two cases. Firstly, there was evidence of abuse during Waldroup’s childhood, which therefore fits with the pattern revealed by Caspi et al. (2002). Secondly, the fact that Waldroup had the MAOA–L allele was raised during the initial, liability trial, i.e. prior to conviction. There was therefore the theoretical possibility that the evidence might have been sufficient to lead to a complete acquittal. As it turned out, the judge reduced the charge (not just the sentence), from first degree murder to voluntary manslaughter. In so doing the sentence was reduce from capital punishment to a maximum of 6 years.17
Stefania Albertani: Two years after Bayout, the Italian courts were the scene for a second controversial use of genetic (and neurological) evidence. In 2009, Stefania Albertani had pleaded guilty to the murder of her sister. Albertani had been stealing from her family to fuel an addiction to shopping. She killed her sister, who had uncovered evidence of Stefania’s financial wrongdoing, and attempted to burn the corpse. Albertani later went on to try and kill her mother who, in turn, was suspicious of Stefania’s role in the earlier death (Farisco and Petrini 2012).
Expert witnesses called by the defence (an unusual feature of the case in its own right, since experts are normally appointed by the Court in Italy) conducted both brain imaging and an evaluation of Albertani’s MAOA status. They reported that there were physical anomalies in the anterior cingulate cortex, and that she had the low-expression allele for MAOA. Both of these factors might contribute to aggressiveness and to compulsive behaviour.
The judge in this case was significantly persuaded by the biological evidence, which he described (probably inappropriately) as being less open to subjective interpretation than traditional psychiatric assessment. He therefore did not go with the prosecution’s recommendation of life imprisonment and instead sentenced Albertani to 20 years incarceration, with the first three to be served in a mental hospital.
Gary Cossey: Before moving on to look at the use of brain imaging in criminal cases, the case of Gary Cossey18 is worthy of comment regarding inappropriate arguments based on molecular genetics. The case is unusual both because it was the judge who sought to introduce behavioural genetics, and because the evidence in question was entirely hypothetical. It serves as a warning regarding the scientific literacy of lawyers, a point to which we will return in Chap. 5.
Cossey was found to be in possession of child pornography, a charge to which he pleaded guilty. At the district court, two psychological assessments that Cossey was a low to moderate risk of re-offending were disregarded by the judge who deemed them to be “virtually worthless”. Cossey was given a sentence of six and a half years imprisonment followed by lifelong supervision.
It might have been legitimate for the court to query the merit of the psychological evidence in light of the fact Cossey had continued to view child porn, even after being the subject of an initial investigation by the FBI. However the determination that he ran a substantial risk of recidivism was actually based on spurious genetics.
The court argued that Cossey had an “as yet undiscovered gene”, a gene about which more might be known in about 50 years. It was, they contended, “a gene you were born with” and “it’s not a gene you can get rid of”.
The appeal court found that basing the risk of reoffending on an unsupported theory of genetics was a “plain error”; they vacated the judgement and remanded the case for re sentencing with the stipulation that it was considered by a different judge!
4.4 Use of Brain Imaging in Criminal Cases
Recent years have seen increasing attempts to use data from newer brain imaging methods within the law courts (for more extensive coverage see Jones and Shen 2012; and Rushing 2014). In the context of the current discussion, where the emphasis is biological determinism and moral responsibility, we will omit all civil cases, and criminal cases in which the plaintiff has sought to introduce brain imaging data, e.g. as evidence of injury. Only examples in which legal teams have sought to use brain data to provide some explanation for the defendant’s behaviour will be considered.19
In reviewing the use of neuroimaging in criminal cases it is also important to remind ourselves of the distinction (elaborated in Sect. 3.1.1) between techniques that reveal information about the structure of the brain, and those purported to demonstrate brain function. A range of approaches including electroencephalography (EEG), Positron Emission Tomography (PET) and functional Magnetic Resonance Imaging (fMRI) offer insight into the operation of the brain. Brain Fingerprinting and the Brain Electrical Oscillations Signature (BEOS) test are variants of EEG.
Our survey of the evolution of the law on insanity, automatism and diminished responsibility (Chap. 2) and on the science of the brain (Chap. 3), have already touched upon cases in which abnormal structures within the brain have been considered to influence the actions of the defendant. In two of these, a brain tumour was deemed to have played a significant role. In the case of the Virginian man with deviant sexual behaviour (Chap. 3), the discovery of a brain tumour was considered to be the root cause of his inappropriate activity and a custodial sentence was reduced to attendance at a therapeutic programme. Earlier we observed that the presence of a tumour led to a verdict of automatism and subsequent acquittal in the case of Charlson (though it is important to be reminded that integral to this outcome was the controversial judgment that the tumour was an “external” not an “internal” factor).
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