Abstract
Recent cases have highlighted the issue of faulty probabilistic reasoning by expert witnesses in courts of law. While concern about potential miscarriages of justice is clearly well-placed, the consequences of such faulty reasoning do not seem to be fully appreciated. These are often counter-intuitive, as we show with two examples: the Interrogator's Fallacy and the Prosecutor's Fallacy. Both demonstrate the danger of relying solely on ‘common sense’ when drawing inferences from legal evidence.