TITLE SEVEN — OPINION AND EXPERT EVIDENCE
Rule 703. Bases of Opinion Testimony by Experts
Base of Opinion. The facts or data in the particular case upon which an expert witness bases an opinion or inference may be those perceived by or made known to the witness at or before the hearing. These include:
facts observed by the witness or otherwise in the witness’s direct personal knowledge;
evidence already in the record or that will be presented during the course of the proceedings, which facts may be assumed to be true in questions put to the witness; and
facts or data not in evidence if the facts or data are independently admissible in evidence and are a permissible basis for an expert to consider in formulating an opinion.
Independent Admissibility Required. The basis of an expert opinion in this State is governed by subdivision (1)(c). An expert shall not rest an opinion upon facts or data that are not independently admissible in evidence merely because experts in the field reasonably rely upon facts or data of that kind. An expert shall not serve as a conduit through which otherwise inadmissible evidence, including inadmissible hearsay, is placed before the trier of fact.
Sufficiency of the Facts or Data. The proponent shall establish that the facts or data are sufficient to support the opinion offered, as Rule 702(1)(b) requires. An opinion resting upon facts or data that are incomplete in a material respect, or that omit a matter the field requires to be considered, is inadmissible; the omission of an immaterial matter bears upon weight.
Time of Acquisition. The facts or data may be perceived by the expert, or made known to the expert, at or before the hearing. An expert may acquire the facts or data by personal examination, by attending the proceeding, by reviewing materials furnished by a party, or by a hypothetical question put by counsel.
Hypothetical Questions.
Permitted Form. An expert may be examined upon a hypothetical question that assumes facts. Every fact assumed shall be in evidence, or shall be evidence that the examining party represents will be introduced during the proceeding.
Statement of Assumptions. The court may require the examining party to state the assumed facts before the question is put, and may require that the question be restated where the assumptions are unclear, incomplete in a material respect, or unsupported.
Failure of the Assumption. Where a fact assumed in a hypothetical question is not introduced, the opinion given in answer shall be stricken upon motion, and the court shall instruct the trier of fact to disregard it.
Cross-Examination. An adverse party may examine the expert upon a hypothetical question that alters, adds to, or omits an assumed fact, provided the altered assumption has support in the evidence or in evidence to be introduced.
Reliance Upon Records of This World. An expert may rely upon an in-game transaction, inventory, banking, or ledger record; a dispatch log or a recording of the Dispatch radio channel; a record of a department or agency; a platform-generated message log, including a Discord channel log, message timestamp, or account metadata; or a record of the electronic filing system, including the docket, a filing timestamp, or a Bates number, provided that the record is independently admissible under Rule 803, Rule 804, or another provision of these rules and is authenticated as Rule 901, Rule 1108, and Rule 1109 require. An expert may rely upon such a record where it has been admitted, or where the proponent represents that it will be admitted, subject to Rule 104(2).
Statements Made to the Expert. A statement made to an expert by a party, by a declarant, or by a person examined is hearsay when offered to prove the truth of the matter asserted, and is admissible only under a provision of Title Eight or another exception recognized by statute, by these rules, or by the common law of Ridgeway. The fact that an expert relied upon the statement does not render it admissible.
Reports of Court-Ordered Examinations. Where an examination is ordered under Rid. R. Civ. P. 26.2 or is otherwise conducted by order of the court, the examiner may rely upon what the examiner personally observed and upon the results of tests the examiner administered. A statement made by the person examined during the examination is governed by subdivision (7), by Rule 505 where the privilege against self-incrimination is invoked, and, in a criminal case, by Rule 505(1)(c).
Failure of the Basis. Where the basis of an opinion is excluded, is not introduced, or is stricken, the opinion resting upon it shall be stricken upon motion. Where a portion only of the basis fails, the court shall determine whether the remainder is sufficient under subdivision (3), and may permit the expert to be re-examined upon the remaining basis.
Foundation Shown by the Expert. The facts or data upon which the expert relied may be established by the expert’s own testimony. The court may require the expert to identify each source relied upon and to state what the expert took from it.