Neuroscience, Neuroethics and the Law
Mr Edmund Naylor1, Mr Daniel Wood2, Prof. Julian Savulescu3
Oxford University Medical School, New College, Oxford, E-mail:
edmund.naylor@medschool.ox.ac.uk, 2Oxford University Medical School, The
Queen’s College, Oxford, E-mail: daniel.wood@medschool.ox.ac.uk, 3Uehiro Centre
for Practical Ethics, Oxford, E-mail: julian.savulsecu@philosophy.ox.ac.u
1
All authors are Medical Students and members of the Oxford Forum for Medical
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Word Count: 1608
Neuroscience, Neuroethics and the Law
Advances in neuroscience have important implications in a legal setting, adding fuel
to a centuries-old debate over the nature of free will and offering the possibility of
‘mind reading’ after and even before a crime has been committed. These issues have
important ethical consequences.
Libertarian free will – the concept that an individual human can be the “uncaused
cause” of his actions – initially appears central to legal responsibility, but its existence
has long been controversial. The concept requires acceptance of the dualist belief that
mind and brain are separate implying that the conscious, the ‘ghost in the machine’, is
able to decide on actions independently of external influences. If one takes the
determinist view that the mind is a construct of the brain then libertarian free will is
impossible. The brain is a physical object in a physical universe, subject to the laws
of causality: thus all neural impulses and eventual decisions are predetermined. Every
action has a reaction even if separated by complex neural processing. If the latter
argument is accepted then every defendant could legitimately claim the automaton
defence: as Gazzaniga (1) has aptly put it "I had no choice but to murder - my brain
made me do it"?
Neuroscience aims to elucidate the mechanisms of brain function – or, in other words,
determine the physical causality of brain processes. As a result, neuroscience is often
used by those arguing for a determinist explanation of the human condition, adding
hard evidence to what was previously a purely philosophical debate. Libet (2) showed
that neuronal impulses initiating conscious action are detectable hundreds of
milliseconds prior to the perception of a conscious decision, suggesting to some that
consciousness is an illusion. This, and other similar evidence, casts doubt on the
extent of libertarian free will.
Others question the impact of this evidence on the dualism-determinism debate.
Neuroscience has yet to come close to explaining integrated command and response
mechanisms within the brain: why, for example, a pupil raises his arm when told to by
his teacher (3). Until neuroscience can explain the mind as neural mechanisms it does
not justify giving up the dualistic explanation: we do after all perceive our own mind
and brain separate.
Other philosophers argue that determinism cannot threaten human free will, no matter
the extent of neuroscientific evidence for the neural mechanisms of the mind.
Compatibilists consider that free will can exist despite determinism, with free will
only lost if an individual is forced to act by another person. As a result, our actions
are free despite being predetermined: it is a fallacy to consider our actions imposed on
us by the laws of nature.
The Consequentialists provide another powerful argument, asserting that libertarian
free will is not in fact necessary for responsibility.
From a consequentialist
viewpoint, laws and specifically punishments for breaking them play a role solely in
improving an individual’s future actions, enabling society to function for overall
benefit. In this system responsibility is determined only by an ability to understand
the law and know the consequences of breaking it; as a result the equation of personal
responsibility with libertarian free will falls.
The extension of the determinist
argument to absolve legal responsibility is thus hardly without challenge.
Advances in our ability to probe the living brain may have a more practical impact on
legal practice. Functional neuroimaging has led to psychiatry exploding into a ‘hard’
scientific discipline.
associated
with
Imaging studies have shown that psychiatric illnesses are
characteristic
changes
pharmacological or psychological treatment.
within
the
brain,
correctable
by
This promises to revolutionise our
understanding of these conditions and improve treatments.
The extension of psychiatric neuroimaging into the legal field has revealed
abnormalities in the brains of antisocial individuals, showing an association with
various crimes (4).
This raises the possibility that individuals with a certain
combination of structural and metabolic abnormalities could be pre-emptively
imprisoned due a possibility of future criminality. Taking the same argument to its
opposite extreme, those accused of crimes could cite similar abnormalities, detected
by neuroimaging, in their defence – if an individual’s brain predisposes him to
violence by its structure, then is he less culpable for his crime?
These potential uses of advanced neuroimaging in a legal setting raise several
important objections.
It must be remembered that neurophysical states are in
themselves neither bad nor good (5): they may only be correlates of bad or good
actions. Currently there is very little evidence for the predictive validity of such tests
making any use in pre-emptive sectioning unsupportable. In order for predictive tests
to be introduced, the predictive value of any test would have to be established, with
society deciding how specific such a test should be: would 10% false positives be
acceptable? Or 1%? The use of neuroinvestigation in pre-emptive imprisonment also
raises objections on the grounds that it would violate certain fundamental rights. It
could lead to a new level of invasion of patients’ mental privacy, dangerously
challenging free thought and speech and going so far as to introduce Orwellian
‘thought crime’. As there is presently little consensus on which brain structures and
activity could be construed as being either ‘criminal’ or abnormal the use of brain
scans to either pre-empt crime or acquit a suspect seems unlikely in the near future.
In spite of the reservations expressed above, the careful use of neuroimaging in this
area could have an important positive effect. If treatment rather than imprisonment
were given to individuals with neurophysical states suggestive of likely future
criminality or indeed to those already convicted of crimes, then a positive outcome
could be achieved for the individual and society. Ethical issues would remain over
imposition of treatment in this situation, however, and the classification of individuals
as physiologically hard-wired to commit future crime would cause controversy (6).
Functional neuroinvestigation may also have a role in assessing quality of testimony.
Researchers have reported the use of functional magnetic resonance imaging (fMRI)
to detect lying, albeit in an experimental setting, to an accuracy of more than 90% (7).
In comparison, traditional polygraphs have no established reliability or accuracy and
are also highly operator-dependent.
Neuroinvestigation could also be used to
determine whether an individual had been present at the crime scene: EEG recordings
have been shown to indicate if a person is familiar with a particular situation (1).
These legal uses of neuroscience could have a positive effect by increasing the
accuracy of conviction.
The accuracy of neuroinvestigations in determining the veracity of witness testimony
remains an issue, however, and would have to be proven in situations where subjects
are highly incentivised to lie. In addition, a US judge has concluded that the use of
neuroscientific evidence should be limited on the grounds that it threatens the jury’s
role in determination of credibility in a trial (8), providing a further objection to the
use of neuroscience in court. It is important that neuroimaging-based analysis is
viewed only as a further piece of evidence to be assessed by the jury, rather than as a
direct insight into the defendant’s mind.
Conclusion
Recent neuroscientific advances have important ethical implications in relation to the
moral basis of the law and in the more practical realm of legal practice. While
neuroscience helps to bring the determinist challenge to free will into focus, it does
not currently threaten legal responsibility: there are powerful arguments that
responsibility remains in spite of determinism. More robust testing of the predictive
and diagnostic power of functional neuroimaging will be required before its legal use
can be increased and even then ethical objections will remain. Neuroscience can have
a positive effect in the legal field, but careful navigation will be required to achieve it.
Box:
fMRI: coming soon to a court near you?
fMRI-based lie detection is yet to make the jump from laboratory to courtroom, but
researchers predict that its accuracy will soon reach a level at which its use will be
irresistible (9).
Two US companies, No Lie MRI and Cephos Corporation, are
developing fMRI lie detection with the aim of using it in the legal setting.
For the companies to succeed in moving fMRI lie detection into the US courtroom,
the technique must fulfil the Daubert criteria, which state that a scientific technique
should have general acceptance from the scientific community and a known error rate
before it can be used as evidence. Scientists in the field feel that once a 95% rate for
lie detection is reached, general acceptance will follow; in comparison the polygraph
machine, which is largely excluded from US courts, is right between 60 and 85% of
the time (9). With recent evidence suggesting that fMRI is around 90% accurate in
detection of lying in an experimental setting (7), this 95% threshold does not seem far
off. In the UK there is no equivalent of the Daubert criteria, potentially making
courts more accessible to fMRI on this side of the Atlantic. Nonetheless cultural
objections to lie detection will remain a barrier in both countries (8).
A second direction for No Lie MRI and Cephos’ energies is towards the large market
for commercial lie detection: 40,000 polygraphs are carried out in the US each year
by insurance companies and government agencies (10), and the use of lie detection to
manage sex offenders has been trialled in Britain.
In 2006 a South Carolina
delicatessen-owner, accused of arson by his insurance company, used No Lie MRI to
support his claim of innocence in an attempt to make the insurers pay up (11). The
out-of-court use of fMRI is likely to spread quickly, especially if a US loophole
allowing fMRI but not polygraph testing of potential employees can be exploited (12).
Acknowledgement
The authors would like to acknowledge the criticism of Sheheryar Kabraji.
References
1. Gazzaniga MS. The Ethical Brain. New York: Dana Press; 2005.
2. Libet B, Gleason CA, Wright EW, Pearl DK. Time of conscious intention to act in relation to onset
of cerebral activity (readiness-potential). The unconscious intention of a free voluntary act.
Brain 1983;106 (Pt3):623-42.
3. Morse SJ. Moral and legal responsibility and the new neuroscience. In: Iles J, editor. Neuroethics.
Oxford: Oxford University Press; 2006. p. 33-50.
4. Eastman N, Campbell C. Neuroscience and legal determination of criminal responsibility. Nat Rev
Neurosci 2006;7(4):311-8.
5. Buller T. What can neuroscience contribute to ethics? J Med Ethics 2006:32:63-64.
6. Wolfe T. Sorry, but your soul just died. In: Hooking Up. London: Picador; 2000. p. 89-109.
7. Kozel FA, Johnson KA, Mu Q, Grenesko EL, Laken SJ, George MS. Detecting deception using
functional magnetic resonance imaging. Biol Psychiatry 2005:58(8):605-13.
8. Greely HT. The social effects of advances in neuroscience: legal problems, legal perspectives. In:
Iles J, editor. Neuroethics. Oxford: Oxford University Press; 2006. p. 33-50.
9. Rosen J. The Brain on the Stand. New York Times 2007 Mar 11.
10. Ireland C. Symposium: ‘Will Brain Imaging be Lie Detector Test of the Future.’ Harvard
University Gazette 2007 Feb 8.
11. McKenna P. Can a brain scan prove you’re telling the truth? New Scientist 2007 Feb 10.
12. No Lie MRI. Customers – Corporations. [Online]. 2006 [cited 2007 Dec 2]. Available from:
URL:http://www.noliemri.com/customers/GroupOrCorporate.htm