Expert Opinion in Court: A Comparison of Approaches

Abstract

Before commencing on a jurisdiction-by-jurisdiction examination of the systems for employing expert testimony, a brief look at the main jurisprudential traditions lays a proper foundation for the subject matter. There are many commentaries on the differences between traditions of legal systems of Europe, the United States, and elsewhere. Most juridical systems fall into one of two groups, each exhibiting dis-tinct legal philosophies and characteristics. On one hand, there is the tradition employed in the English-speaking world, which is typically described as the Anglo–Saxon jurisprudence, commonly referred to as employing an adversarial approach. On the other hand, there is the civil law system that is based on the Napoleonic Code, which in turn was modified from the Roman Law model. The civil law system is often called the inquisitorial or investigative system. An effective comparison of the two main legal philosophies is fraught with difficulties. Both systems share some terminology, but the terms used have significantly different meanings in each. The rules of how the tribunals function, what the roles of various law professionals are, and how decisions are made, including the uses of juries and panels of judges, also differ between these two systems. The inquisitorial system is broadly based on a search for the truth and is structured around an exhaustive analysis of the evidence by a specialist judge or, as this official is called in the French legal system, the juge d'instruction or examining mag-istrate. One who is familiar with the inquisitorial system might be tempted to compare the examining magistrate to the prosecutor of the American system, but such comparison is inappropriate. An examin-ing magistrate is a member of the judicial branch, whereas a prosecutor is typically in the service of the executive branch. The adversarial system is grounded on a system of rules of evidence designed to limit the factual evidence that may be presented to the court. The pur-pose of these rules of evidence is to avoid injecting into the lay jury's fact-finding process, any proof that is of little relevance to resolving disputed issues. Fur-ther, judges in adversarial system jurisdictions have the ability to also exclude evidence of doubtful reli-ability or that would unfairly prejudice the jury to an accused in a criminal case. This does not occur in civil law systems where all evidence is effectively analyzed by the examining magistrate, although it must be added that the examining magistrate does not have any role to play in any subsequent trial. In the adversary system, questions of fact are decided by a jury, or, if no jury is present (called a bench trial), by the judge. In a jury trial, the judge decides the issues of law and instructs the jurors in the legal principles that they must apply to the facts, as they have found them to be established by evi-dence that has been presented. The most common type of evidence that is excluded from the trier of fact in adversary system courts is evidence of bad char-acter. The rationale behind excluding, what in many cases can be directly relevant evidence, is that the evi-dence of the bad character of the accused may have a prejudicial effect on the minds of jurors that out-weighs its probative value, thus leading to a verdict based on prejudice rather than fact. Counsel for the accused would, at the Voir Dire, which is the prelimi-nary hearing before the court and conducted without a jury, make an application (or present a motion) that certain evidence should not be admitted. In England and Wales, the rules on bad character evidence estab-lished for over 100 years in the Criminal Evidence Act of 1898, have now been fundamentally altered by the passage of the Criminal Justice Act of 2003, which increased the circumstances where evidence of character is admissible despite its potential prejudicial effect. Other evidence that has increasingly come under scrutiny for exclusion is autoptic or forensic evidence. The use of forensic evidence is of powerful probative value, but it can also be inherently misleading in that the reliability of scientific evidence often falls below the trier of fact's faith in it. In recent years, a number of high profile cases regarding expert testimony have drawn attention to the often fallible nature of such evidence. Forensic evidence is now much more likely to be questioned at the Voir Dire as to not only its relevance but also its accuracy. One common misconception held in the adversar-ial world is that, in civil law systems, the accused is guilty until proved innocent. That is incorrect. All European civil law systems are intimately tied to