Dirty tricks of cross-examination

A mock jury study was conducted to test the hypothesis that perceptions of a witness can be biased by presumptuous cross-examination questions. A total of 105 subjects read a rape trial in which the cross-examiner asked a question that implied something negative about the reputation of either the victim or an expert. Within each condition, the question was met with either a denial, an admission, or an objection from the witness's attorney. Results indicated that although ratings of the victim's credibility were not affected by the presumptuous question, the expert's credibility was significantly diminished—even when the question had elicited a denial or a sustained objection. Conceptual and practical implications of these findings are discussed.This research was supported by funds provided to the first author by the Bronfman Science Center.     

Traffic accidents and drivers suspected for drug influence

All records from the Danish Medicolegal Council concerning drivers suspected for drug influences were examined for the 5 year period 1981-1985. 461 records were included, 62 women and 399 men. In 250 cases drugs from more than one of ten groups had been taken thus making 786 combinations of drug/driving. The major drug group was benzodiazepines, accounting for 65% of all drug intake. Opioids also contributed substantially, found in 38% of the cases. A traffic accident had occurred in 180 (39%) of the records. Drivers who had been taking antidepressives were involved in an accident in 67%, significantly above the mean. For benzodiazepines, the corresponding percentage was 43%, while for opioids it was only 23%, significantly below the mean. This striking difference has been demonstrated in most of the studies concerning drugs in traffic. It may support the hypothesis that opioids do not necessarily make driving dangerous, as do antidepressives, barbiturates and especially benzodiazepines.     

Bounding the number of contributors to mixed DNA stains

We derive a simple inequality for the probability of observing a given DNA profile when assuming a fixed number of unknown persons have contributed to the mixed stain. We then show how this inequality can be used to obtain an upper bound for the number of unknown contributors needed to be considered.