The article discusses the increasingly common practice of the Supreme Court of Finland of using psychology-based generalisations on its own initiative when evaluating witness evidence. Using the much-discussed decision KKO 2019:54 by the Supreme Court as a springboard for discussion, the article examines the benefits, challenges and implications of this practice. The article argues that using psychological generalisations ex officio has the potential to improve testimony evaluation and remedy incorrect practices while providing a practical and cost-effective way for judges to increase the use of scientifically supported evaluation criteria. However, the article also identifies various pitfalls relating to the practice, particularly with regard to the assessment of the quality of psychological research and the application of its probabilistic results. These limitations should be adequately addressed in order to support correct and predictable application of psychological generalisations. Addressing these limitations is essential, since the Supreme Court’s practice has already led to an increasing pressure on the Finnish courts to apply psychological generalisations to their testimony evaluation.

Key words: evidence, witness testimony, testimony evaluation, witness psychology, generalisations