Police perceptions of eyewitness impairment due to alcohol and other drug use: a cross-cultural comparison

Victims, witnesses, and suspects of crime are frequently intoxicated by Alcohol or Other Drugs (AOD) during the event. How intoxication is perceived by investigating officers, and the manner in which this is handled during interview procedures, can affect the quality of information obtained and therefore investigative outcomes. Various factors are likely to contribute to how intoxication is handled during the investigation of a crime, including standard procedures, familiarity with the effects of different substances, and cultural attitudes. While findings with respect to the effect of different substances on memory are still emerging, it is important to investigate whether police beliefs are consistent with available evidence. In this study, Australian and Indonesian police officers were surveyed about their perceptions of memory accuracy and credibility of victims and witnesses intoxicated with various substances (e.g. alcohol, cannabis, amphetamines, and opioids). A higher proportion of Australian police identified larger negative memory effects associated with alcohol intoxication. At the same time, Indonesian police were found to be more likely to report that intoxication with alcohol would make a victim or witness less credible. With regard to timing, across multiple substances, larger proportions of Australian police reported believing that information obtained from witnesses that were still intoxicated would be more accurate than if interviewed after they became sober. It is concluded that, in order to rectify misconceptions about the impact of AOD intoxication on memory and improve investigative practices, both Australian and Indonesian police would benefit from additional training on the effects of intoxication.