Expert evidence must distinguish fact from opinion, says David Smith
There is an important distinction made between types of evidence in England and Wales—witness evidence that relates to fact and evidence that relates to opinion. The first is admissible while the second is not. The distinction is often hard to spot.
In truth, all evidence is opinion evidence to some extent in that the same events may appear to occur in an entirely different manner due to a difference in the way they recall or interpret the events, or because of a conscious or unconscious bias. The court resolves this problem by grouping issues of interpretation and bias under the general heading of witness credibility.
Opinion v fact
For example, a passenger in a car cannot give factual evidence about the speed that the car is travelling unless they have actually looked at the speedometer. They can give factual evidence about how frequently lampposts were passing the windows and as to how the car was moving in relation to other vehicles on the road, from which the court may be able to draw inferences
