Psychological evidence in court: Legal developments in England and the United States.

Psychological testimony in England, except when it has dealt with clinical matters, has generally been ruled inadmissible on the grounds that it would usurp the function of the jury to decide matters of “common knowledge and experience”. The so-called Turner rule governing admissibility of psychological evidence has been interpreted according to a dubious assumption about the transparency of human behaviour, but this restrictive interpretation was rejected in a recent Court of Appeal decision, which should result in a more receptive attitude to psychological evidence. In the United States, the Frye test has been used to exclude psychological testimony unless it can be shown to have gained “general acceptance” in the field of psychology, but a recent United States Supreme Court decision has led to a more permissive approach in that jurisdiction also.