The role of the psychologist expert witness: provider of perspective and input.

The definition and role of the expert witness is reviewed. Two conceptual systems for viewing the world, the scientific method and the adversarial system, are compared. The reconciliation and integration of these two discrepant systems are discussed in terms of input versus outcome. The rules of evidence, as well as problems of communication between the systems, are reviewed with the aim of providing expert witnesses with a better understanding of effective testimony. Finally, collaboration between the two systems is called for in order to provide guidelines for both neuropsychologists and attorneys.