Criminal Law Expert Evidence – Understanding PTSD

Understanding how PTSD can support a defence in criminal proceedings

Understanding how PTSD can support a defence in criminal proceedings

Post Traumatic Stress Disorder (PTSD) can be used to support a defence in criminal proceedings. Although PTSD research concerning criminal defence remains scant, there have been several recent criminal law cases in which the issue of PTSD has been analysed, particularly in regard to sentencing.

Understanding PTSD - Expert Court Reports

What is PTSD?

PTSD is a maladaptive and debilitating psychiatric disorder. It involves re-experiencing, avoidance, negative emotions and thoughts, and hyperarousal in the months and years following exposure to severe trauma. Around 6–8% of the general population have experienced PTSD, although this can increase to 25% among people such as combat veterans, refugees, assault victims, and others who have experienced severe mental trauma.

The risk of developing PTSD following a traumatic event/s is determined by genetics (30–40% of the risk of PTSD is heritable) as well as factors such as childhood abuse or other past trauma.

PTSD is treated with a mix of medication and therapy, the most popular types being Cognitive Behaviour Therapy (CBT) and eye movement desensitisation and reprocessing (EMDR).

How does PTSD apply to criminal defence?

PTSD is often used in cases where the Defendant is arguing the partial defences to murder, namely loss of control and diminished responsibility. It can also be a consideration in the defences of automatism, duress, and insanity.

In the case of R v Rejmanski (Bartosz) [2017] EWCA Crim 2061; [2018] 1, the defence argued that the Defendant killed his housemate after the deceased triggered his PTSD through comments about the conduct of soldiers in the Afghanistan war and derogatory remarks about the Polish army.

Two psychiatrists and two psychologists were instructed as expert witnesses to assess R’s mental state following an initial assessment that R may be suffering from post-traumatic stress disorder (PTSD) following his military service. Despite having differing opinions as to the pervasive nature of the PTSD, all agreed that he was, in fact, suffering symptoms of the disorder. The question at trial was to what extent the PTSD symptoms affected his life and particularly his capacity for self-control and tolerance under section 54 of the Coroners and Justice Act 2009.

Partial defence to murder: loss of control

(1) Where a person (“D”) kills or is a party to the killing of another (“V”), D is not to be convicted of murder if—

    1. D’s acts and omissions in doing or being a party to the killing resulted from D’s loss of self-control,
    2. the loss of self-control had a qualifying trigger, and
    3. a person of D’s sex and age, with a normal degree of tolerance and self-restraint and in the circumstances of D, might have reacted in the same or in a similar way to D.

On appeal, the judge accepted that, in principle, PTSD could qualify as a “relevant circumstance’ for jury consideration but that the trial judge had “properly resisted” the defence’s efforts to dilute the objective standard as laid out in s. 54 (1)(c). According to evidence heard at trial, the Defendant contended that his PTSD resonated in the form of nightmares and flashbacks to his military service, yet he could not provide any evidence that he was suffering from any such flashback at the time of the deceased’s death.

In R v Huckerby [2004] EWCA Crim 3251, the appellant (H) applied for leave to appeal against his conviction for conspiracy to rob and for leave to call fresh evidence for the purposes of the appeal. Expert evidence showed that H had been suffering from PTSD. The psychotherapist and Senior Cognitive Behavioural Psychotherapist detailed in his expert report:

“I am of the opinion that his unresolved PTSD symptoms from the first incident were further exacerbated and reactivated at the time of the second robbery … This combined with a significant sense of subjective life threat, together with fear and helplessness, would serve to explain his behaviour at the time of the robbery, i.e. opening the doors. In addition, his belief that he should have done more to help his colleague at the first incident (though he realises objectively there is little he could do at the time) may also have influenced his actions because he believed his colleague to be at severe risk during the second robbery .”

The report went on to say:

“Mr Huckerby’s actions in the second incident may not therefore have been immediately rational to the observer, or to someone going through the sequence of actions retrospectively … I found his account of his events and symptoms to be credible. At the time of the second incident — the incident for which he has been punished — Mr Huckerby’s actions were most probably determined as much or more so by his PTSD and instincts than any logical reasoning …”

The Court allowed the appeal, ruling that the Prosecution’s case had been conducted on the basis that H’s actions at the time of the robbery were explicable only because he had been a willing participant. Had the jury been aware that PTSD may have caused H to panic and to cooperate in circumstances in which he would not have otherwise done, his evidence as to an innocent motivation might have been accepted.

In conclusion

Expert evidence is crucial in criminal prosecutions where the Defendant claims they had PTSD as the disorder can drastically affect decision-making. If you wish to delve deeper into what PTSD is, please watch our latest video:

How PTSD Affects Decision Making: Unveiling Expert Observations (

How PTSD Affects Decision Making: Unveiling Expert Observations


You can also visit our featured expert’s profile for more insights and in-depth knowledge. Click the link in the description to explore their extensive experience and contributions.

How can Expert Court Reports Ltd help?

Expert Court Reports provides expert witnesses and medicolegal court reports for solicitors, barristers and other agencies including the police, probation services, prisons, and third-sector organisations as well as private clients. To discuss any issues raised in this article, please call us on 01865 587865, email, or request a call by completing our online form.