Sleep disorders/Sexsomnia: The role of the expert and the external/internal factor dichotomy

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review


Since 2005, there have been a number of cases in which defendants charged with sexual offences have claimed that they carried out the acts alleged whilst sleeping, seeking to use the condition sexsomnia as the basis of a defence of either insanity or automatism. This chapter considers the role of the forensic sleep expert in establishing a defence based on sexsomnia. We discuss the limitations on the conclusions that can be drawn by sleep experts, based on clinical evaluation and other relevant factors. In order to properly understand the context in which expert evidence is admitted, we explore the application of the internal/external factor test to sexsomnia cases and the appropriateness of the test in such circumstances. We also consider the potential impact of the recent amendments to Part 33 of the Criminal Procedure rules and the associated Criminal Practice Direction on the admissibility of forensic sleep expert evidence in sexsomnia cases.
Original languageEnglish
Title of host publicationMental Condition Defences and the Criminal Justice System
Subtitle of host publicationPerspectives from Law and Medicine
EditorsBen Livings, Alan Reed, Nicola Wake
Place of PublicationNewcastle upon Tyne
PublisherCambridge Scholars
Number of pages450
ISBN (Print)9781443871617
Publication statusPublished - 1 Feb 2015


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