If an expert testifies relying on inadmissible facts, what must the expert do?

• A. Present only admissible data and omit any caveats.
• B. Avoid mentioning the inadmissible nature of the data.
• C. Explain the basis and limitations, and disclose the reliance on the inadmissible data while noting its status.
• D. Refuse to testify.

Answer: (C)

Experts may base their opinions on facts or data that would be inadmissible to prove the opinion’s truth, as long as those materials are the kind reasonably relied upon by others in the field. When giving the opinion, the expert should explain how they arrived at it, including the data or information used and the limitations of that basis. If some underlying data are inadmissible, the expert must disclose that reliance and note the inadmissible status of the data, so the court and jury understand the basis for the opinion and its potential weaknesses. This transparency helps the trier of fact evaluate the reliability of the testimony without to be misled by the admissibility status of the data itself. Presenting only admissible data or omitting caveats would misrepresent how the opinion was formed, and refusing to testify isn’t necessary when the expert can clearly explain the basis and its limitations.