ABSTRACT
Expert witnesses may be called in many fields, only some of which involve science. In the case of image analysis, there is a scientific basis that underlies the testimony. This may possibly involve such diverse fields as mathematics, computer science, optics, electronics, the psychology and physiology of human vision, microscopy, and of course whatever fields are involved in the analysis of the evidence shown in the images. The expert is supposed to be able to assist the decision makers (the jury) in understanding and interpreting the evidence. But the expert is hired by one of the advocates (counsel) and not by the court itself. This is not the practice in many European countries, where expert witnesses are brought into the case by the judge, but it is the situation in common law countries such as England, Canada, and the United States.
