Which of the following does not belong to expert testimony?

Which of the following does not belong to expert testimony?

• A. An expert may testify without any data if the judge allows.
• B. An expert may testify only if they have specialized knowledge and rely on reliable data.
• C. An expert's opinion does not need to be based on data.
• D. An expert's opinion is always admissible regardless of data.

Answer: (B)

The key idea is that expert testimony must be grounded in specialized knowledge and backed by reliable data or facts. An expert is allowed to testify only if they have relevant expertise and their opinions are based on sufficient data and reliable methods properly applied to the facts. This combination—qualification plus data-backed reasoning—is what the court’s gatekeeping rules (like Daubert and FRE 702) require to ensure that expert opinions are credible and helpful. This is why the statement that an expert may testify only if they have specialized knowledge and rely on reliable data is the best fit. It directly reflects the core requirements: the expert must be qualified and must base their opinion on data and reliable principles. The other statements conflict with these standards: an expert cannot testify without data; an expert’s opinion must be based on data; and admissibility is not automatic regardless of data.

The key idea is that expert testimony must be grounded in specialized knowledge and backed by reliable data or facts. An expert is allowed to testify only if they have relevant expertise and their opinions are based on sufficient data and reliable methods properly applied to the facts. This combination—qualification plus data-backed reasoning—is what the court’s gatekeeping rules (like Daubert and FRE 702) require to ensure that expert opinions are credible and helpful.

This is why the statement that an expert may testify only if they have specialized knowledge and rely on reliable data is the best fit. It directly reflects the core requirements: the expert must be qualified and must base their opinion on data and reliable principles. The other statements conflict with these standards: an expert cannot testify without data; an expert’s opinion must be based on data; and admissibility is not automatic regardless of data.