Post-traumatic stress disorder and the law

This contribution explores the forensic application of post-traumatic stress disorder (PTSD) in civil and criminal cases. The key aspect of acting as an expert witness is to keep within one's area of expertise and to be clear as to the evidence base underpinning any opinion given. It is helpful to use a range of measures to assess PTSD – both clinical examination and validated psychological measures – and to be rigorous and transparent in terms of specifying which diagnostic classification is being applied and where the patient or client does or does not meet the criteria. The relative advantages and disadvantages of using the DSM-IV versus the ICD-10 are discussed briefly. Clinicians must be aware of the potential for exaggerating or even falsifying symptoms, particularly where compensation is being sought and guidance is provided as to ways in which the genuine can be distinguished from the false litigant. Although PTSD is used mainly in criminal law as mitigation or a defence in individuals who are charged with an offence, psychiatric evidence is increasingly being used to support, or discredit, claims of victimization (e.g. in rape cases) and some guidance is provided as to forensic aspects of assessing rape victims and giving expert evidence in rape trials.