Expert opinions are often the backbone of a case and a critical component to achieving justice. These experts decode complex technical information into unbiased facts for the courts to use in making legal decisions. Without them, unjust legal outcomes could result from misinformation or a lack of understanding of technical subjects.
Experts are expected to be closely questioned on the facts, data and methodology used to form their opinions. They may also be asked to testify about the reliability of their conclusions. These tests are not a trivial exercise and it is not uncommon for an expert’s opinion to be excluded by the court if it does not meet certain criteria set out in Daubert v Merrell Dow Pharmaceuticals, Inc.
The first and most obvious requirement is that the expert have actual, hands-on knowledge of the subject matter about which he or she is opining. The expert must be able to articulate the specific facts and observations he or she has made, preferably with concrete examples. The second requirement is that the expert’s theory or methodology be generally accepted in a relevant scientific community.
Lastly, the expert should be able to present a reliable conclusion based on a reasonably high degree of probability. Often experts will not explicitly state the percentage of likelihood or the factual assumptions or physical observations on which their opinion is based. Prod them to do so and explain how their specialised knowledge is used to produce that opinion. Otherwise, the expert’s bald conclusions will be inadmissible, rendering their entire testimony nugatory.
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