[Thesis]. Manchester, UK: The University of Manchester; 2014.
In many jurisdictions, including England and Wales, psychopaths are unable to succeed
with an insanity defence. This has been influenced by a legal view of psychopathy
as a condition characterised by a reduced ability to comply with the law, which is
otherwise fully understood. Evidence from cognitive neuroscience, however, may potentially
challenge this traditional legal conception of psychopathy. In this regard it has
already been suggested, based partly on scientific evidence, that it may be appropriate
for at least some psychopaths to succeed with an insanity defence where they can be
shown to lack moral competence.In this thesis, I critically examine this possibility.
I first examine the insanity defence in English law, showing how psychopaths have
effectively been excluded from the defence by judicial interpretation of the insanity
defence criteria. Consequently, if psychopaths lacking moral competence were to be
identified, reform (or reinterpretation) of the defence would be required. I then
present philosophical arguments in favour of the case that some psychopaths should
gain access to an insanity defence, before clarifying which psychopaths ought potentially
to succeed, and which criminal offences ought potentially to be relevant, for the
purposes of a reformed or reinterpreted defence. In order to clarify which psychopaths
are relevant psychopaths (RPs), it is necessary to go beyond existing scientific evidence.
It is argued, based on emerging neuroscientific findings and current research techniques,
that while it is not currently possible to identify RPs, it may be possible in the
future. Even if it this becomes possible, however, the philosophical case for access
to an insanity defence remains deeply problematic. Although RPs may lack moral competence,
for example, they may nevertheless possess other capacities relevant to criminal responsibility.
After closer examination, it is argued that the case for access to an insanity defence
may be best viewed as a case for mitigation rather than exculpation. I conclude by
considering some of the implications of this analysis in an English legal context,
should it become possible to identify RPs. Of particular relevance is the possibility
that RPs may be at high risk of causing serious harm to others. This illuminates important
possible relationships between responsibility and risk, and diagnostic advancements
and risk assessment, in this area. There are also broader implications for the management
of psychopaths in the future, given that greater scientific understanding may lead
to enhanced predictive abilities that could tempt policymakers towards more radical
strategies.This thesis contributes to an ongoing debate about the role that cognitive
neuroscience may play in decisions about the criminal responsibility of psychopaths.
My main contribution is to clarify how psychopaths lacking moral competence may be
identified in the future, and relate this neuroscientific discourse to arguments for
providing these persons with access to an insanity defence. It is argued, however,
by reference to legal, policy, scientific and philosophical considerations, that the
risk such persons would pose, rather than their capacity for criminal responsibility
per se, may have significant legal and policy implications in England and Wales in