Opinion ID: 1919140
Heading Depth: 1
Heading Rank: 21

Heading: general admissibility standards for expert testimony

Text: [10,11] Before admitting expert opinion testimony under Neb. Evid. R. 702, [98] a trial court must determine whether the expert's knowledge, skill, experience, training, and education qualify the witness as an expert. [99] If the opinion involves scientific or specialized knowledge, trial courts must also determine whether the reasoning or methodology underlying the expert's opinion is scientifically valid. [100] Under Daubert, evidentiary reliability depends on scientific validity. [101] Normally, after a court finds that the expert's methodology is valid, it must also determine whether the expert reliably applied the methodology. [102] Finally, under Neb. Evid. R. 403, [103] the court weighs whether the expert's evidence and opinions are more probative than prejudicial. [104] [12] Here, the parties do not dispute Frank's qualification to give expert medical testimony or to interpret epidemiological studies. We see the broad issue as whether under our Daubert/Schafersman framework, Frank based his opinion on a reliable, or scientifically valid, methodology. Under that framework, the proponent of expert testimony must answer two preliminary questions by a preponderance of the evidence. First, is the expert's reasoning or methodology underlying his or her testimony scientifically valid? Second, can the finder of fact properly apply that reasoning or methodology to the facts? [105] [13] In determining the admissibility of an expert's opinion, the court must focus on the validity of the underlying principles and methodologynot the conclusions that they generate. [106] And reasonable differences in scientific evaluation should not exclude an expert witness' opinion. [107] The trial court's role as the evidentiary gatekeeper is not intended to replace the adversary system but to ensure that `an expert, whether basing testimony upon professional studies or personal experience, employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field.' [108] In sum, while the trial court acts as the evidentiary gatekeeper, it is not a goalkeeper. [14,15] But a trial court has discretion to exclude expert testimony if there is simply too great an analytical gap between the data and the opinion proffered. [109] An expert's opinion must be based on good grounds, not mere subjective belief or unsupported speculation. [110] Good grounds mean an inference or assertion derived by scientific method and supported by appropriate validation. [111] [T]he expert must have `good grounds' for his or her belief in every step of the analysis. [112] Yet courts should not require absolute certainty. [113] [A] trial court should admit expert testimony `if there are good grounds for the expert's conclusion' notwithstanding the judge's belief that there are better grounds for some alternative conclusion. [114]