SB 1309 revises Missouri’s rules governing the admissibility of expert witness testimony in civil, family, juvenile, probate, and other nonjury proceedings, and it also updates the general standard for expert testimony in all other actions. The bill repeals and reenacts section 490.065, which is Missouri’s core expert-evidence statute, to clarify when a qualified expert may testify, what foundation must be shown, and how courts should evaluate whether expert opinions are reliable and helpful to the trier of fact.
For the categories covered by subsection 1, the bill allows expert testimony when specialized knowledge will assist the fact-finder, permits opinions that embrace an ultimate issue, and requires that the facts or data relied on be reasonably relied upon by experts in the field and otherwise reasonably reliable. For all other actions, the bill adopts a more detailed reliability framework requiring proof that the testimony is based on sufficient facts or data, reliable principles and methods, and a reliable application of those methods to the case. It also addresses when underlying facts may be disclosed to the jury, limits expert opinions on a criminal defendant’s mental state, and preserves an owner’s right to testify about the reasonable market value of their land.
Impact
The bill would amend Missouri’s evidence code by replacing section 490.065 and changing the standards courts use to admit expert testimony. Its practical effect is to refine judicial gatekeeping over expert evidence, especially in civil litigation, while preserving existing exceptions for family, juvenile, probate, and nonjury matters and for landowner valuation testimony. The bill would affect litigants, attorneys, judges, and expert witnesses by clarifying the admissibility threshold and the permissible scope of expert opinions.
Sentiment
Based on the bill text and available context, the measure appears to be a technical evidentiary reform rather than a highly controversial policy proposal. The caption indicates it is intended to modify the admissibility of expert testimony evidence, suggesting a procedural and judicial-administration focus. No committee transcripts or recorded votes were provided, so there is no documented floor or committee sentiment to indicate support or opposition beyond the bill’s neutral drafting tone.
Contention
The main points of potential contention are the reliability standard for expert testimony and the extent of judicial discretion in admitting or excluding expert opinions. Parties favoring stricter evidentiary screening may support the bill’s emphasis on reliable methods and sufficient facts, while litigants who rely heavily on expert witnesses may be concerned about increased challenges to admissibility. Another possible issue is the criminal-case limitation preventing experts from opining on a defendant’s mental state, which could be viewed as preserving the jury’s role but also as narrowing expert testimony in certain defenses.