A spectator at a professional hockey game was injured when an errant hockey puck flew over the glass boards and struck him in the head, causing permanent eye damage. The spectator brought an action for negligence against the facility owner in federal district court under diversity. By statute, the state in which the federal court is located allows the use of assumption of the risk as a defense when a spectator is injured at a sporting event. Although no valid federal statute or rule governs this issue, federal courts have generally not permitted facility owners to raise an assumption of the risk defense, to encourage facility owners to take more stringent precautions regarding spectator safety. The federal court opted to apply federal common law to resolve the issue, and the resolution was in the spectator's favor. However, a different outcome would have occurred if the district court had applied state law. Was the court's application of federal common law proper?