A recent, well-publicized case in which murder during sleepwalking was offered as a defense, underscores the fact that sleep medicine specialists are asked to render opinions or judgements regarding culpability in legal cases regarding violence claimed to have arisen from sleepwalking episodes. This review addresses this difficult issue from scientific, clinical and legal aspects, with emphasis upon the need for further research, calling for close collaboration between the legal and medical (both clinical and basic science) professions.