External quality assessment of laboratory performance in analysis of toxicological cases

A mean of 44 members of the United Kingdom national external quality assessment scheme (UKNEQAS) for toxicology reported analytical findings on 10 toxicological cases circulated between December 1995 and February 2000. Material distributed usually consisted of a 5ml blood and a 20ml urine sample simulated by quantitative addition of drugs and their metabolites to material donated by volunteers and patients. The samples were accompanied by a brief outline of the circumstances surrounding the case. Laboratories were requested to report their analytical findings, list methods of analysis, and provide interpretation of their findings. The mean overall success rate for identification of drugs or their pharmacological group was 76%, failure being largely by laboratories providing an immunoassay-based screening service for a fixed range of drug groups. The latter laboratories indicated that cases would be referred to regional toxicology centres for further investigation or confirmation. The coefficient of variation of measurements was <7% for routine analytes, such as ethanol and paracetamol, but 26-44% for tricyclics and opiates. There were 3% false positive reports. The quantity and content of interpretative comment provided by the laboratories was very variable. A number provide nothing in addition to the analytical result.     

Impact of hypnotic testimony on the jury

In the past decade, the forensic use of hypnosis to enhance the memories of victims, witnesses, and defendants has sharply increased. A great deal of controversy surrounds this issue. Some commentators argue that testimony derived from hypnosis should not be allowed as evidence because of its inherent unreliability and the unduly powerful impact it may have on a jury. In the present research, we used a jury simulation technique to study the impact that a hypnotically refreshed witness has upon jurors' decision making. A major finding is that jurors view hypnotic testimony with a certain amount of skepticism. In some respects, its impact is comparable to that of testimony based on delayed recall, and rarely does it have the impact of testimony from an immediate report. In addition, jurors' judgments about hypnotically refreshed testimony affected the way they evaluated other evidence at trial: Jurors who learned that a prosecution witness had been hypnotized were less believing ofother prosecution witnesses than were jurors not exposed to hypnotic testimony. The forensic application of these findings is discussed.This research was supported by a grant from the National Science Foundation, Law and Social Sciences Program. We thank Jane Goodman, Doug Leber, Bonnie Sawnson, Russ Wade, Karen Guest, Jonna Barsanti, Don Kline, Elaine Sullivan, and David Kuykendall for their help at various stages of the project.