Expert testimony on the diagnosis of psychopathy is becoming increasingly common in Canadian criminal courts, and may be used to justify more severe sanctions. This article compares expert testimony by mental health professionals with current research on the assessment, prediction, experimental findings, and treatment of psychopathy. As this review will indicate, substantial gaps exist between testimony given by some mental health professionals and current empirical research. The authors argue that substandard testimony has the potential of unduly influencing judges and resulting in unjustifiably harsher judicial dispositions. The authors further contend that such potential could result in abuses of human rights.