What defines an expert witness?

• A. A witness who can testify about public speaking.
• B. A witness who has knowledge not normally possessed by the average person.
• C. An eyewitness.
• D. A police officer.

Answer: (B)

At the heart of defining an expert witness is the ability to bring specialized knowledge beyond what an average person would have, and to help the court interpret complex evidence. This expertise comes from extensive training, education, or experience in a particular field, such as forensic analysis, statistics, or chemistry, and the testimony explains how the evidence was generated and what it means for the case. That’s why the statement describing knowledge not normally possessed by the average person is the best fit—expert testimony hinges on interpreting technical material for the trier of fact.

In contrast, an eyewitness testifies about direct observations of events, which is lay information about what happened rather than interpretation of specialized data. A police officer might be an expert in certain contexts, but simply being a police officer doesn’t automatically make someone an expert; the person must have demonstrated expertise in a specific area and the court must deem that expertise helpful in understanding the evidence.