Good science, well presented, can be an invaluable aide to a court's deliberations. For this reason, scientists entering the courtroom to offer expert evidence are accorded a privileged position. Unlike other witnesses, who are limited to providing evidence of fact, they are allowed to provide the court with their expert opinions. With this privilege however come responsibilities. The aim of this document is to set out these responsibilities, to indicate how they can be addressed and, perhaps most significantly, to indicate sources of reference and advice, relevant professional bodies and codes of conduct which are available to assist the novice. Key issues of which the expert needs to be aware when they take on forensic commitments include:
1) The requirement for expert evidence and opinion to be reliable. The privileged status and weight accorded to expert evidence makes a clear moral case for any expert evidence presented to be dependable. More practically, any court case, no matter how dignified the procedures appear, is a fight between two sides and all evidence is open to challenge. A scientist offering expert evidence or opinion must therefore be able and prepared to demonstrate, sometimes under aggressive questioning, that their work was valid.
2) The overarching requirement for the expert to be impartial. The expert's responsibility is to the court, not to the side providing their instruction and/or payment. This requirement has been clarified in a number of key cases, including 'the Ikarian Reefer' in the civil courts and the Judith Ward judgement in the criminal courts, and is now also spelt out in a number of legal and professional Codes of Conduct. 3)The need for timely provision of evidence. Delays, and subsequent costs, have been identified as key problems within the legal system. Major initiatives, including the Woolf Reforms in the civil courts and the Narey Reforms in the criminal system, have been established to tackle these problems. The expert has to play their role by agreeing a time-scale for their work and ensuring that this time-scale is met. A raft of other issues, some procedural, some practical and some presentational, need to be considered by scientists preparing to enter the legal arena. This document is intended both to alert them to these issues and to identify the resources on which they can draw to help them bring their expertise to the assistance of the courts.