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Corroboration instructions, Rape, Sexual offenses, Jury instructions, Victim testimony


Applied Statistics | Courts | Criminal Law | Criminal Procedure | Evidence | Judges | Litigation


The rules of evidence have evolved, in the main, to protect the jury from being misled, prejudiced or confused by certain types of evidence which might be presented to it. The rules attempt to achieve this purpose by utilizing a number of techniques, which were fashioned by common law judges. First, evidence which gives rise to these dangers might be excluded from the jury's consideration altogether. Secondly, such evidence might have to be corroborated by other evidence before the jury is permitted to reach a verdict in the case. Thirdly, the judge might be compelled to instruct the jury that it is dangerous to reach a verdict solely on the basis of this type of evidence. It is this third technique of increasing the probability of a correct jury verdict that was the subject of the experiment described in this paper.

In most common law jurisdictions, the judge must caution the jury that it is dangerous to convict in the absence of corroboration, on the testimony of an accomplice, a child, or a victim of a sexual offence. The actual instruction the judge gives the jury, when the testimony of one of these categories of witnesses is given in a trial, can be conveniently divided into two parts: first, the judge must warn the jury that it is dangerous to convict on the testimony of the witness alone; second, he or she must list for the jury the independent evidence in the case that the jurors might find corroborates the testimony of the witness.

We sought to test the efficacy of this method of jury control by designing an experiment around a hypothetical rape case. In many jurisdictions this instruction is no longer required in rape cases. The results of the study not only support the wisdom of this legislative change, but also shed light on the efficacy of the instruction as it applies to accomplices and children. Thus, while the remainder of this paper refers to rape cases, the analysis also applies to cases in which these other categories of witnesses give testimony. If corroboration instructions do have an effect on juries, it is important to know what that effect is.

Publication Citation

Published in: Osgoode Hall Law Journal, vol. 15, no. 3 (December 1977).