Monday, October 12, 2009
showed that a group of psychiatrists who evaluated mental competence from case files of 156 criminal defendants performed at a strikingly high level of accuracy.
In an average of 29 out of every 30 cases, the psychiatrists could distinguish competent defendants from incompetent defendants. That’s a level of performance that exceeds standard diagnostic performance in other areas of medicine, such as spotting breast cancer in mammograms or using advanced imaging methods to detect Alzheimer’s disease.
It also points out one of the basic truths of the justice system, even when dealing with a topic as definitive as expert testimony: ultimate decisions still come down to judgment calls.
“These results help us see how courtroom experts can be quite accurate in distinguishing competence from incompetence, but still reach different conclusions,” says Mossman of the study, which was published online in “Law and Human Behavior,” the journal of the American Psychology-Law Society. “It’s a matter of where experts draw the line on the issue of competence.”