Contributions of psychology beyond the expert evidence

This paper raises the need for the law and the courts to use scientific knowledge from psychology. More specifically, it suggests the role of different psychological and social processes in obtaining, interpreting and evaluating the evidence. To do this, it addresses the problem of the expert’s testimony and the admissibility of the evidence by providing empirical research that dispu- te the distinctiveness of legal reasoning. The different consideration or status granted to psychology compared to other forensic disciplines is verified, as well the use by legal operators of not scientifically validated common-sense beliefs and its adverse effects, as it occurred in some decisions of the Spanish Supreme Court. In particular, those referring to guiding criteria to assess the credibility of the victims.
Additionally, different areas in which the law can benefit from the knowledge of legal psychology are proposed, and a broader approach to the role of the expert is recommended. On the other hand, knowledge of psychology, especially cognitive psychology, will be applied to explain errors in forensic tests. The implications for the finding of facts and the quality of decision-making are also analysed. Finally, it is advocated for more significant interaction between academics/professionals of psychology and law, as well as the need for empirical studies based on the professionals of the justice system as participants.