Guilbeau owned and operated Barrel of Fun, Inc. (P). One of its businesses burned down, and P attempted to collect on a fire insurance policy issued by State Farm Fire & Casualty Co. (D). D claimed the defense of arson and filed a counterclaim and a third-party subrogation claim for property damage sustained by other tenants in the building. The district court did not allow Dey to testify about the Psychological Stress Evaluation (voice stress analysis) that he gave to Guilbeau. The district court allowed an arson investigator for the Fire Marshall's Office to testify about his opinion, based on the results of the PSE given by Dey, that Guilbeau both knew about and set the fire. D received judgment. P appealed, claiming that this testimony should not have been allowed.