Bases of an Expert’s Opinion Testimony

An expert may base an opinion on facts or data in the case that the expert has been made aware of, reviewed, or personally observed. If experts in the particular field would reasonably rely on those kinds of facts or data in forming an opinion on the subject, they need not be admissible for the opinion to be admitted. Notes and Comments Comment to 2015 Restyling: All references to an “inference” have been deleted because this makes the Rule flow better and easier to read, and because any “inference” is covered by the broader term “opinion.” Courts have not made substantive decisions on the basis of any distinction between an opinion and an inference. No change in current practice is intended.