It sounds like the issue he was arguing was that in that initial assessment (of 11 tests - not all about PTSD), she said her diagnosis of PTSD was based on the PCL 5. She had spoken to the gold standard for diagnosing but didn't use it herself initially. The PCL Is most often used to measure changes in symptoms and filled out by patients in the waiting room before each therapy session type thing. It is also used in research because it is so quick. It is more of a screening tool or monitoring tool. Often also used to see if there is a need to assess PTSD symptoms further. It can - if someone scores quite high be used for a provisional diagnosis, for example so someone can access resources while awaiting a full assessment. The cut off is flexible as to what score would consitute PTSD because it just isn't really meant to be used that way. Without knowing what other PTSD specific tools she used in that initial assessment, it is hard to know how heavily she relied on this tool. For a forensic psychiatry assessment, it would be a weak tool. Just not really what it was intended for. and so many better PTSD tools out there.