Requiring a proponent to demonstrate that it is more likely than not that certain specialized knowledge will help the trier of fact to understand evidence before certain qualified witnesses may testify.

SB 398 is a proposed Kansas bill that would change rules for expert witness testimony in court. It requires parties introducing expert testimony (the "proponent") to prove, before testimony is allowed, that the expert's specialized knowledge is more likely than not to help the judge or jury understand the evidence or decide a fact in the case. The bill adds specific requirements: the testimony must be based on sufficient facts, use reliable methods, and the expert must have properly applied those methods to the case. This would apply to qualified expert witnesses in civil and criminal cases where specialized knowledge is offered as testimony. The bill is currently pending in the Judiciary Committee after being introduced on January 27, 2026.