JEFFERSON CITY, Missouri- A new Missouri law signed by the governor today will alter the standard for vetting expert witnesses in jury trials. It was co-sponsored by five Republicans.

The legislation was signed at a Jefferson City trucking company.

“Today, we signed an important piece of legislation that will help create more jobs. For too long in Missouri, we’ve had low expert witness standards, which allowed crooked trial lawyers to bring frivolous lawsuits and use fake experts peddling junk science. That scares away businesses and destroys jobs. We took the common sense step today to bring our standards in line with other conservative states. We will keep trial lawyers from picking your pockets and costing Missourians their jobs,” Greitens said.

Those against the law said it would make it more costly to go to court.

The legislation will allow judges to decide whether experts’ testimony is based on “sufficient facts” and other criteria and whether it could be heard in court. A similar law was passed but ultimately vetoed by Gov. Jay Nixon.

Summary of legislation (HB 153):


This bill specifies that a witness who is qualified as an expert may testify in the form of an opinion or otherwise if the expert’s specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue, the testimony is based on sufficient facts or data, the testimony is the product of reliable principles and methods, and the expert has reliably applied the principles and methods to the facts of the case. An expert may base an opinion on facts or data in the case that the expert has been made aware of or personally observed. If experts in the particular field would reasonably rely on those kinds of facts or data in forming an opinion on the subject, such facts or data need not be admissible for the opinion to be admitted. However, if the facts or data would otherwise be inadmissible, the proponent of the opinion may disclose them to the jury only if their probative value in helping the jury evaluate the opinion substantially outweighs their prejudicial effect. An expert opinion is not objectionable just because it embraces an ultimate issue. In a criminal case, an expert witness must not state an opinion about whether the defendant did or did not have a mental state or condition that constitutes an element of the crime charged or of a defense. The bill specifies the provisions do not prevent a landowner from testifying as to the value of their land. Unless the court orders otherwise, an expert may state an opinion and give the reasons for it without first testifying to the underlying facts or data. However, the expert may be required to disclose those facts or data on cross-examination. Certain actions are excluded from the provisions of this bill, including actions in the family courts, juvenile courts, the probate division, and all other actions or proceedings in which there is no right to a jury trial.