A response to Dr. Gudjonsson's commentary

We thank Dr Gudjonsson for his thoughtful response to our article on a complex and controversial issue. He places our paper in the context of the Home Office commissioning independent ‘experts’ to conduct risk assessments. It was indeed such an assessment that inspired us to write the paper and to draw attention to some of the concerns for professional and ethical practice. In our view, the central arguments of our paper still hold, and therefore we are grateful for the opportunity to address the points he makes. First, our central argument is that there is no proper empirical basis for applying existing risk assessment scales used in mental health settings to the population under discussion. Dr Gudjonsson’s response does nothing to address that criticism. His contention that an ‘informed and valid risk assessment of convicted terrorists provides important information for authorities seeking to protect their citizens from future harm’ is both unfounded (there are no informed or valid assessments available) and untested (there are no outcome data that indicate it would be helpful even if there were). The standard type of evidence we would expect to see to support the use of a risk assessment measure would consist, for example, of a followup correlational study or an experimental trial. A recent review of the most widely used instruments for violence risk assessment, including the HCR-20, has been reported by Farrington, Jolliffee, and Johnstone (2008). That review relies, as scientifically we would expect it to, on evidence from followup studies of prisoner cohorts and similar sets of data. As far as we can establish there is no parallel to this in relation to persons who have engaged in terrorism. If there is, it seems odd that Dr Gudjonsson does not cite it.