Abstract
Psychiatrists and psychologists acting as expert witnesses in court cases are often accused of bias or error. We examined the level of agreement and factors influencing agreement between expert reports admitted into evidence during adversarial civil proceedings. The inter-rater reliability of the psychiatric diagnosis was examined in 51 pairs of civil medicolegal reports written by experts engaged by the same side and 97 pairs of experts engaged by opposite sides. Reports written by experts engaged by the same adversarial side had good agreement about the presence of a mental disorder ({kappa} = .74) but had only fair agreement about the specific psychiatric diagnosis (average {kappa} = .31). Reports written by experts engaged by opposing adversarial sides had poor agreement about the presence of any mental disorder and also the specific psychiatric diagnosis. Experts were more likely to agree about the presence of a mental disorder if the plaintiff was involved in a fatal accident. The agreement of treating doctors and experts was similar to that of pairs of experts.