An expert witness is a person who has a recognised, specialist knowledge, a skill or experience in a particular area, such as doctors, dentists, engineers but not necessarily confined to professionals as they can be experienced motor engineers, mechanics, plumbers etc.
Experts are usually asked for a written opinion which may not necessarily be used in a court case. The party seeking the opinion may decide, before or during the hearing not to actually use the opinion.
It is important to note that the expert witness has no link or association with any of the parties in the case. They are independent and are required to give an unbiased opinion. It is incorrect to believe that an expert witness is ‘on the side’ of the party calling and paying their fee. The essential purpose of the expert’s opinion is to assist the court in their deliberation of the matters being argued by the litigants.
Another purpose of calling expert witnesses in court cases is to assist the judge on subjects that might be outside the judge’s own field of knowledge or understanding. For instance, where a structure collapsed and caused damage and or injury, an expert could assist the court in giving their opinion on whether the structure was built in a proper and safe way.
The expert should confine their opinion entirely to matters within their own knowledge and not speculate.
Experts should be informed and up to date on their subject matter or field of expertise otherwise their evidence might be easily rebutted.