Expert Evidence and the Intoxicated Offender

Abstract

This paper considers the role of the expert witness in cases where people charged with criminal offences allege that they were grossly intoxicated when the act in question was committed. Expert evidence concerning the effect of intoxication on accused people may be relevant at two stages of the trial: in deciding whether they acted voluntarily and with criminal intent; and in imposing a penalty if the offence is proved. The paper will examine each of these aspects in turn. In each part, the law concerning admissibility of expert evidence of this type will be summarized. Then, in the context of specific cases, the types of questions and answers that are likely to be put, will be described and examined. The aim of this analysis is to draw to the attention of both expert medical witnesses and lawyers, the problems of testimony on the possible effects of intoxication on mental processes and the implications that that may have in imposing criminal responsibility on intoxicated offenders and making appropriate dispositions. The usual outcome of such evidence will be considered and it will be suggested that although expert evidence is far more satisfactory at the sentencing stage of a criminal trial than at the earlier stage when guilt is being determined, there is at both stages a real risk that the expert witness may usurp the role of the arbiter of fact — either the jury or the magistrate or judge. Notwithstanding this risk, however, few accused persons are acquitted because, due to gross intoxication, they cannot be proved to have acted consciously and voluntarily and the sentencing judge or magistrate has the final discretion in making an appropriate disposition. Although the paper is concerned principally with expert evidence on intoxication, the comments apply also to expert evidence on other issues.