Ethics and the Expert Witness: Statistics on Trial

When a statistician appears as an expert witness at trial, most judges and juries expect the expert witness to be a true expert. Yet the adversarial rules of the common law legal system often make it difficult for statisticians to proceed in a manner similar to that which they encounter in academic settings. The situation is exacerbated in a battle of expert statistical witnesses before the court. As a consequence, it is the statistical profession that is often on trial, not simply a defendant. This paper is, at least in part, about the seduction that occurs when a statistician becomes an expert witness at trial and how the statistician can attempt to protect against the most pernicious aspects of the game associated with the use of expert witnesses in the adversarial process.