Bill > HB263

This bill modifies Missouri's rules regarding expert witness testimony across different types of legal proceedings, establishing more specific standards for when and how expert witnesses can provide testimony. For cases involving family law, juvenile courts, probate proceedings, and certain other actions without jury trials, experts can testify using specialized knowledge if their testimony helps understand evidence or determine facts, and they can offer opinions on ultimate issues. For other types of legal actions, the bill introduces a new standard requiring the proponent of expert testimony to demonstrate that it is "more likely than not" that the testimony meets specific criteria, including helping the trier of fact understand evidence, being based on sufficient facts, using reliable principles and methods, and reliably applying those principles to the case. The bill also clarifies that experts can base opinions on facts they've been made aware of or observed, and adds a specific prohibition in criminal cases against experts opining on a defendant's mental state or condition that constitutes an element of the crime or a defense. Notably, the bill preserves the existing provision allowing property owners to testify about their land's reasonable market value.

Justice

https://house.mo.gov/Bill.aspx?bill=HB263&year=2025&code=R