Course-focused and contextual, Criminal Law provides a succinct overview of the key areas on the law curriculum balanced with thought-provoking contextual discussion. Mens rea refers to the mental element necessary for a particular crime. This may differ from one crime to another and the definition of each crime must be examined to determine what state of mind is required. This chapter discusses the meaning of intention, knowledge, recklessness, wilfulness, direct intent, oblique intent, ulterior intent, transferred malice, and mistake. These mens rea topics raise important questions about the extent to which a person is responsible and therefore deserving of blame and punishment. A revised and updated ‘The law in context’ feature examines critically the debates between those who favour subjectivist and objectivist approaches to mens rea, with particular reference to reform of the offence of unlawful act manslaughter.