As of August 28, 2017, the Daubert standard will now govern the admissibility of expert witness testimony in certain cases in Missouri. This is the result of House Bill 153, one of the first bills signed by Governor Eric Greitens, which effectively changes the language in Missouri Revised Statute Section 490.065 moving the standard for admissibility of expert testimony from a broad to more stringent standard requiring the Court to assess the basis of a proposed expert’s testimony before allowing the expert to testify at trial.
The new language in the statute makes it clear that in order for expert testimony to be admissible, it must meet a heightened standard, requiring the Court to specifically find that:
(a) The expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) The testimony is based on sufficient facts or data;
(c) The testimony is the product of reliable principles and methods; and
(d) The expert has reliably applied the principles and methods to the facts of the case.
In lieu of the old standard which allowed expert testimony if it was based on facts and data “reasonably relied upon” by experts in the field, this new standard requires the Court to function as the gatekeeper of expert evidence in accordance with Daubert. As the gatekeeper, the Court must consider the soundness and reliability of the methodology and processes employed by proposed experts in coming to their conclusions and whether the experts applied the methodologies and processes to the specific facts of the case. It is not the role of the Court to evaluate the conclusions of the expert witness; however, it is incumbent on the Court to assess whether the proposed expert’s testimony is based on sufficient facts or data, whether the testimony is the product of reliable principles and methods, and whether the expert has reliably applied the principles and methods to the facts of the case at hand.
The new language in Section 490.065 mirrors Federal Rule of Evidence 702. In Daubert v. Merrell Pharmaceuticals, Inc., 509 U.S. 579 (1993), the United States Supreme Court held that FRE 702 superseded the common law standard for governing expert witness testimony taking the determination about the reliability of a methodology out of the hands of specific fields of study and placing that responsibility with the judge. Daubert, 113 S.Ct. at 122. Pursuant to FRE 702, for expert testimony to be admissible it must be the product of reliable principles and methods and those principles and methods must be applied to the actual facts of the case. Under the common law standard, there was no requirement of an examination of the methods underlying how experts formed their opinions, which effectively allowed for the admission of “junk science” simply because a methodology was accepted by a given field. Daubert made it clear that both the reliability of the methods used to form an opinion as well as their relevance to the particular facts of the case were to be assessed before expert testimony is admissible.
Hence, there is a significant practical difference between the old standard and the new Daubert-modeled standard set forth in the revised Section 490.065. Under the new statute, the Court must take a fairly deep look at the methodology underlying an opinion. Before, no such analysis was necessary, as the inquiry was based solely on whether the methodology was generally accepted in the expert’s field. Now, the Court must conduct probing inquiries into the foundation of a proposed expert’s opinion. For example, if the expert relies on studies, the Court should examine those studies to determine if they are themselves reliable and similar enough to the facts of the case to be a reliable basis for an expert opinion. Likewise, if an expert relies on testing a hypothesis, the Court should examine the test performed by the expert to determine if that test was itself a reliable test, and further, whether the test simulates or recreates the facts of the case such that its results are relevant to the specific facts at issue. These are the types of inquiries that are required under Daubert, and why expert witness testimony has to meet a higher standard before it is admissible.
With the adoption of the new language set forth in Section 490.065, Missouri law now requires Courts to apply the Daubert standard when assessing the admissibility of expert testimony. Therefore, an expert should only be permitted to testify if these criteria are met: (1) the testimony is based on sufficient facts or data; (2) the testimony is the product of reliable principles and methods; and (3) the expert has reliably applied the principles and methods to the facts of the case. The admission of expert testimony simply based on that expert’s use of some method or principle reasonably relied upon by those in the expert’s field will no longer be allowed without further review of that method or principle. The new standard requires review of the science behind the opinion, as Courts will need to evaluate the reliability of the methods or principles employed by the expert.
Whether and to what extent the new statute will apply to cases that have been filed prior to August 28, 2017, has yet to be seen. Generally, in the absence of legislative intent that a statute apply retroactively, statutes are presumed to apply proactively, leaving pending actions unaffected. Here, the statute itself does not express an intent that the amendments apply retroactively, so there is an argument that the new standard would apply to cases filed after August 28 only.
However, if the presumption normally favoring prospective operation is overcome, the inquiry will be whether the statute is substantive or procedural in nature. Substantive laws are those that create, define, take away, or impair existing rights; whereas, procedural laws are those that prescribe a method of enforcing rights or redressing for their invasion. The distinction between substantive law and procedural law is that substantive law relates to the rights and duties giving rise to the cause of action, while procedural law is the machinery used for carrying on the suit. If the amended statute was intended to apply retroactively, such application would be permitted only if the amendments were found to be procedural rather than substantive.
We can anticipate litigation over whether the change in the statute is procedural versus substantive and whether, at the end of the day, the statute will apply to cases already pending. The statute is certainly procedural in nature in that it impacts the manner and mechanism by which a jury would receive evidence. It changes only the method by which expert testimony is to be evaluated for admissibility at trial; it does not change substantive rights or whether an individual is entitled to make certain claims or seek redress for certain wrongs. Therefore, there is a good basis on which one can argue that this statute is procedural in nature and should apply to cases already pending before August 28.
To that end, we can anticipate parties looking to the Court to assess the reliability of the scientific methods or principles relied upon by experts proposed to testify at trial before it is determined that the expert’s testimony is admissible. We can also anticipate potential litigation over the application of the new standard to cases already pending. Indeed, for cases filed after August 28, the new expert standard will apply
 Cases regarding juvenile courts, family courts, probate division and cases with no right to a jury trial will not be subject to the Daubert standard under the new law.
 See Mo.Rev. Stat. § 490.065.2(a)-(d).