§ 8.01-401.1.Opinion testimony by experts; hearsay exception (subsection (a) of Supreme Court Rule 2:703, subsection (a) of Supreme Court Rule 2:705, and subsection (a) of Supreme Court Rule 2:706 derived from this section).

Expert witnesses build opinions on a foundation of facts, data, and professional experience, and § 8.01-401.1 spells out how much of that foundation has to be shown before the opinion itself can come in. The core rule is permissive: an expert may testify to an opinion or draw an inference from facts, circumstances, or data made known to or perceived by the expert at or before trial, and none of that underlying material needs to be independently admissible in evidence, so long as it is of a type professionals in the expert’s field normally rely on when forming opinions.

On direct examination, the expert can give the opinion and the reasons for it without walking through every underlying fact first, unless the court orders otherwise. That shortcut disappears on cross-examination: the opposing side can always require the expert to disclose the underlying facts or data that support the opinion.

The section also opens a narrow hearsay door for published treatises, periodicals, and pamphlets on medicine, science, or other technical subjects, once the source is established as reliable authority by testimony or stipulation. Statements from such sources can be read to the jury — but not entered as physical exhibits — whether they come up on cross-examination of the opposing expert or are offered by the calling party’s own expert on direct. If a party wants to use a treatise passage on direct examination, the specific statements must be designated as literature and shared with the other side at least 30 days before trial, unless the court orders otherwise; once properly designated, the expert need not have relied on the passage when forming the opinion to read it into evidence.