Lie detection research has reached a stage where theory building is possible. We believe practitioners should contribute to theory as it is being developed. With this in mind, we briefly review contemporary theories - namely the Adaptive Lie Detector theory and Truth Default Theory - and consider the practical implications for reducing bias and increasing accuracy when making lie-truth judgements. There are practical issues that theory has yet to address, which are briefly considered. This article intends to spotlight the on-going academic work in lie detection in hope that practitioners will feedback to researchers about how theory may relate to their work, and in turn help steer the direction of future research.