On August 22, 1997, David Webber (plaintiff), Holly Bray, and Brandy Sobba (defendant) were seriously injured in a car accident after they had been drinking. Sobba, who was driving the car, claimed that Webber had made physical advances on her at the time that she hit a bridge abutment. Webber sued Sobba for negligence in the United States District Court for the Eastern District of Arkansas under its diversity jurisdiction. Sobba pleaded comparative fault and joint enterprise as defenses. Webber moved for summary judgment on the joint-enterprise defense. Webber argued that, under Arkansas law, the joint-enterprise defense was unavailable. The district court denied the motion, finding that the Arkansas Supreme Court would have allowed Sobba to bring the defense. The case went to trial, and the district court instructed the jury that it should find in favor of Sobba if it found that Webber and Sobba were engaged in a joint enterprise. The jury found in favor of Sobba. Webber appealed.