PTSD and the Law

AuthorBronagh O'Hanlon
[2020] Irish Judicial Studies Journal Vol 4(2)
Abstract: This article looks at medical advances in PTSD and at anticipated future developments. The article
traces the development of the law on negligently inflicted psychiatric damage and shows how law and medicine
interface on this topic.
Author: Ms Justice Bronagh O’Hanlon. Contributions by Angela Brennan BCL, Christian J. Scally LLB
and Lisa Fitzsimons LLB.
Post-Traumatic Stress Disorder (PTSD) has been described as ‘Psychiatry’s Problem Child’,
in particular when looking at the provision of evidence to identify a duty of care not to cause
a psychiatric injury. This paper looks at the difficulty in gauging the existence and severity of
the psychiatric injury both medically and legally. It examines how the courts in various
jurisdictions have addressed the complexities that arise in establishing that the disorder was
reasonably foreseeable and resulted from a defendant’s negligence.
The beginning of the paper examines the medical and scientific advances that have provided
a better understanding of the condition of PTSD and its aetiology and then continues to
outline the psychiatric criteria necessary for the diagnosis of the disorder in the forensic
setting. The second part of the paper looks at how the law in this area has developed in the
common law jurisdictions of Ireland, England, North America and Australia.
Diagnosis of PTSD: Medical Advances
Since the first codification of PTSD in the USA Psychiatric Association (APA) Diagnostic and
Statistical Manual of Mental Disorders (DSM-III) and subsequently, in the World Health
Organisation’s (WHO) International Classification of Disorders (ICD-10), studies have shown that
its development follows exposure to a variety of traumas, many of which have become a
common occurrence in modern times. Those suffering PTSD typically experience flash-
backs, avoidance of thoughts/feelings associated with trauma and hyperarousal or
hypervigilance. Although medical advances are continuing to gain a more complete
understanding of the impact of such trauma on the nervous system, Murray B. Stein MD,
Professor of Psychiatry and Family Medicine and Public Health and Vice-Chair of Clinical
Research in Psychiatry at the University of California, remarks how studies in
pathophysiology have shown that PTSD is a disorder characterised by dysfunction within
specific brain systems.
Perhaps one of the greatest difficulties to date in providing a diagnosis of pure PTSD is the
fact that the associated symptoms of the disorder are also present in other psychiatric
Peter Gaughwin, ‘Psychiatry’s Problem Child: PSTD in the Forensic Context’ (2008) 16(5) Aus tralian
Psychiatry 369, 369-370.
Pathophysiology definition: ‘The study of the physiological changes that occur in the body both naturally and
as a result of disease’. See Murray B. Stein and others, ‘Structural Brain Changes in PTS: Does Trauma Alter
Neuroanatomy?’, (1997) 21 Ann NY Acad Sci 76.
[2020] Irish Judicial Studies Journal Vol 4(2)
conditions such as major depressive disorder and panic disorder.
In a legal context, such
uncertainty as to a definitive diagnosis of PTSD creates difficulties in the recovery of
damages and, as previously mentioned, has been described as ‘Psychiatry’s Problem Child’.
However, despite the current inability of neuroscience to definitively make a diagnosis of
PTSD, many medical and scientific advances in areas such as neuroimaging,
electroencephalography (EEG) and genetic biomarkers have made strides towards piecing
together the complex parts of the puzzle in an attempt to conclusively define its aetiology.
Neuroimaging such as Functional Magnetic Resonance Imaging (fMRI) and Diffusion
Tensor Imaging (DTI), have contributed to a greater understanding of the physiology of fear
and the pathophysiology of PTSD, by identifying three particularly affected areas of the
brain, the hippocampus, the amygdala, and the medial frontal cortex.
Across different stress
and anxiety disorders, studies in neuroimaging have allowed scientists to identify patterns of
hyper-activation in emotion generating regions and hypo-activation in prefrontal and
regulatory regions of the brain. The different patterns emerging from such studies are
contributing to the ability of scientists to better situate specific disorders along a continuum,
ranging from fear-based reactivity to more diffuse and prolonged stress or apprehension.
Regarding the latter, research and neuroscientist Lynn Selemon at the Yale School of
Medicine explains that studies have identified three frontal lobe circuits that have proved
important in the understanding of PTSD symptomology:
(1) The conditioning fear extinction circuit.
(2) The salience circuit. (Evaluation and response to stimuli).
(3) The mood circuit.
Selemon further explains that:
It is viewed that the circuitry of fear conditioning and fear-conditioned
extinction are intimately involved in the Pathology of PTSD. In PTSD the
unconditioned negative stimulus is the traumatic event, and the conditioned
stimuli are the sights and sounds and other sensory experiences that occur
concurrently with the event. In PTSD, a failure to extinguish fear responses,
which would normally happen in people not experiencing the disorder,
contributes to the persistent physical and cognitive symptoms of re-
experiencing the trauma, including increased autonomic arousal and phobic
Hugh Koch and others, ‘Post-traumatic Stress Disorder Contemporary Analysis of Medico Legal Evidential
Issues’ (2019) 28 The Expert Witness Journal.
Gaughwin (n 1).
David J Nutt and Andrea L. Malizia, ‘Structural and functional brain changes in posttraumatic stress disorder’
(2004) 65 The Journal of Clinical Psychiatry 11.
Elizabeth R. Duval, Arash Javanbakht and Israel Liberzon,‘Neural circuits in anxiety and stress disorders: a
focused review’, (2015) 11 Therapeutics and Clinical Risk Management 115.
Lynn D. Selemon and others, ‘Frontal Lobe Circuitry in Posttraumatic Stress Disorder’ (2019) 3 Chronic
Stress (2019) 1.

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