the district court took its cue from daubert v. merrell dow pharmaceuticals, which had solidified a gatekeeping role for trial judges in admitting expert testimony. under daubert, certain factors contribute to the reliability, and hence the admissibility, of expert testimony, one of which is the general validity of the expert's methods. the district court found the tire expert's methods not to be scientifically valid, and hence excluded his testimony. this meant that kumho tire would prevail. the carmichaels appealed to the eleventh circuit.