This article reviews the utility of expert opinion in legal proceedings and the deployment of expert witnesses in adversarial litigation. The use of expert witnesses to assist courts in making just and fair conclusions may be contrasted with the partisan interests of those who call them. An adversarial system is a bad method of scientific enquiry and undermines the court's capacity to reach the 'right' answer. As a consequence, courts may reach the wrong conclusion based on bad science. The role of the expert as a witness places strain on an expert to provide certainty, where in fact there may be none. Recent reforms in the civil courts have changed little and the problem is even more acute in criminal trials. The expert can rely solely on the integrity of his or her own opinion, tempered with a little humility. However, when filtered through the rhetoric and advocacy of a court arena, even this may be compromised.