In the medico-legal context, expert witnesses are required, under the Practice Direction supplement to the Civil Procedure Rules Part 35 for Experts and Assessors (2005), to “indicate if … they are not satisfied that an opinion can be expressed finally and without qualification” (p.10). This declaration in an expert report for the courts in the UK requires that the expert would have assessed the confidence they have in the opinion expressed in their report. While experts preparing a medico-legal report will therefore draw upon their specific professional expertise as the basis for their confidence in the opinions expressed, few experts will have formal training in the assessment of deception, and not all will be readily familiar with the broader literature,1–5 theory and research relating to assessment of deception and malingering. There is an established literature6–9 in psychology on “lying” which addresses key aspects relevant to the evaluation of an individual's presentation at interview. This psychological literature can play a key part in the necessary knowledge base for interviewers who must evaluate the validity of an individual's reported difficulties, and assess the confidence they have in the interview process. This article briefly reviews research relating to malingering, lying and deception in so far as it relates to the medico-legal setting.