Since the first attempt to indict a corporation for gross negligence manslaughter in the 1920’s, legal reform surrounding corporate manslaughter has been discussed in political and legal arenas. This research answers the question of whether turning points of corporate manslaughter reform in England and Wales were inhibited by reasons of marked similarity between 1912 and 1999. This will be achieved using a legal research strategy that embraces doctrinal law, legal history and archival research which will in turn establish seven turning points of corporate manslaughter reform. By addressing the events and disasters that occurred around these seven turning points of corporate manslaughter reform, it will be shown that there are consistent reasons of marked similarity which inhibited corporate manslaughter reform in the twentieth century. The outcome of these findings is used to set out the methodological and epistemological stance taken through the reasons of marked similarity involving judicial reasoning and the use of post-disaster reactive legislation, associated with corporate manslaughter reform. Reasons of marked similarity inhibited the type of legal reform considered at the expense of other opportunities which would have reflected the changing corporate structure of the twenty-first century. The impact of those reasons of similarity on preferred change resulted in the introduction of the Corporate Manslaughter and Corporate Homicide Act 2007 in April 2008.