Abstract: Your first thoughts about statistical expert witnesses might be of matching fingerprints or DNA in criminal cases. The debate about the safety of the conviction of Lucy Letby for multiple murders is partly driven by the exclusion of statistical evidence by the Crown Prosecution Service. Senior lawyers claim no statistical evidence was used in the trial, even though a barrister asked ``What's the chance of that?" 
 
So what is ``statistics" and how can statisticians assist civil and criminal courts? I have enjoyed a wide range of challenging questions as an expert.  which suggested various research questions. I will illustrate from my experience the role and responsibilities of an expert witness in preparing reports and in courts. 
 
Police and barristers often approach academics for assistance with evidence. However, while academics are happy to do science, few are willing to act as expert witnesses. I would like to encourage more statisticians to contribute to judicial processes, and I am willing to provide some advice. One obvious reward is financial. Ideas for research and exercises for teaching also arise. There is also satisfaction in serving society.