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Expert Witness Testimony and Opinion

Section 490.065, RSMo increased the standard for the admissibility of expert witness testimony in Missouri. The legislation took effect in 2017 to combat what was perceived to be low standards for expert testimony and high jury verdicts in favor of plaintiffs on medical malpractice and/or product liability claims. The new law brings Missouri’s expert witness standards in line with the federal Daubert standard.

There are a few key requirements in Section 490.065: (1) the witness must be qualified as an expert by knowledge, skill, experience, training, or education and may testify in the form of an opinion if, (2) the scientific, technical or specialized knowledge wil help assist a judge or jury understand the evidence or determine a fact in issue, (3) the testimony is based on sufficient facts or data, (4) the testimony is the product of reliable principles and methods and (5) the expert has reliably applied the principles and methods to the facts of the case.

If all of these requirements are not met, then an expert is not permitted to render an expert opinion. Consequently, attorneys, through depositions or trial testimony, will often attack an expert to demonstrate that one or all of these things are not present to block the expert from testifying as to his or her opinion.