The crime of unlawful act manslaughter (otherwise known as constructive manslaughter) exists in English and Australian common law. It is also an offence contrary to the Canadian Criminal Code. In all three jurisdictions the offence shares the same essential elements, including the requirements that the accused commit an act which is both unlawful and dangerous. This article will explore the case law on unlawful act manslaughter in Australia, Canada and England, focusing on the elements of an unlawful act and dangerousness, in order to identify similarities and differences in the application of the law in the three jurisdictions. Where differences are found, consideration will be given to the question whether English law should be reformulated.