Missouri Senate Bill SB918

Missouri 2026 Regular Session

• Introduced: 1/7/26
• Refer: 1/8/26

Caption

SB 918

Summary

SB 918 rewrites Missouri’s expert witness statute, section 490.065, to set out when expert testimony may be admitted in court. The bill preserves the general rule that experts may testify when their specialized knowledge will help the fact-finder, but it reorganizes and clarifies the standards for admissibility in different types of cases. In family, juvenile, probate, and other non-jury proceedings, the bill keeps a more traditional formulation allowing expert opinions based on reasonably reliable facts or data and permitting opinions on ultimate issues, subject to the court’s discretion on hypothetical questions. For all other actions, the bill adopts a more detailed reliability framework. It requires the proponent of expert testimony to show that the testimony is based on sufficient facts or data, is the product of reliable principles and methods, and reflects a reliable application of those principles to the facts of the case. It also addresses when an expert may rely on otherwise inadmissible facts or data, limits disclosure of such material to the jury unless its probative value substantially outweighs prejudice, and bars experts in criminal cases from opining on whether a defendant had the mental state or condition constituting an element of the offense or defense. The bill also preserves the right of property owners to testify about the reasonable market value of their land.

Impact

The bill would repeal and replace Missouri’s existing expert testimony statute, affecting evidentiary standards in civil and criminal proceedings across the state. It would align Missouri’s general expert-admissibility rules more closely with a reliability-based framework for expert evidence, while retaining separate rules for family, juvenile, probate, and non-jury matters. Courts, litigants, and expert witnesses would be directly affected, especially in cases where the admissibility of scientific, technical, or specialized testimony is contested.

Sentiment

Based on the bill text and caption, the measure appears to be a technical evidentiary reform rather than a highly partisan policy change. The available record shows no committee transcript, vote history, or recorded opposition, so there is no documented public debate in the provided materials. The bill’s tone suggests an effort to clarify and modernize expert testimony standards, which typically draws support from those seeking more predictable court rules.

Contention

The main points of potential contention are the stricter reliability requirements for expert testimony in most cases and the criminal-case limitation preventing experts from testifying about a defendant’s mental state or condition as an element of the offense or defense. Those provisions could be viewed by supporters as necessary safeguards against unreliable or overly prejudicial expert evidence, while critics might argue they make it harder to present specialized testimony. Another possible issue is the bill’s different treatment of family, juvenile, probate, and non-jury proceedings versus other actions, which creates a split evidentiary standard.