Adversarial systems and court-centered systems approach the use of expert evidence very differently. This article focuses on the perspectives held by judges and other process participants on bias and partisanship in expert reporting in Australia and the Netherlands. It aims to provide insight into the origins of, and reasons for, bias and partisanship, focusing on psychological and psychiatric expertise. The first part of the article explains differences between adversarial and court-centered systems with respect to the involvement of experts. The second part examines judicial attitudes with respect to partisanship and bias and the way in which these issues are dealt with in the two systems. The article explores how these systems provide safeguards against partisanship by the experts.