8. Opinion evidence

The Concentrate Questions and Answers series offers the best preparation for tackling exam questions. Each book includes typical questions, bullet-pointed answer plans and suggested answers, author commentary and diagrams and flow charts. This chapter explores an area of evidence law dominated by expert witness evidence and the extent to which flawed testimony leads to miscarriages of justice. Expert evidence is now commonplace in criminal and civil trials, and the courts and Parliament have developed procedures to ensure that it is of high quality. These are an eclectic mix of common law and statute and their development reflects the importance of scientific expertise. It is necessary to be familiar with the differences between expert and non-expert opinion evidence and on when and in what circumstances both types are admissible and questions that can be asked of the expert whilst giving evidence. The approach depends on whether the question relates to civil or criminal trials.