Tompkins was injured on "a dark night" by something protruding from a passing freight train owned by Erie Railroad Company as Tompkins stood next to the tracks in Pennsylvania, He claimed the accident occurred because of negligent operation of the train. Tompkins was a citizen of Pennsylvania, and Erie was a company incorporated in New York. Tompkins (the plaintiff) brought suit in federal district court.
Erie argued that the court, in deciding the case, should apply the law of Pennsylvania. Under Pennsylvania law, Tompkins was a trespasser, and Erie would not be liable for his injuries. Tompkins argued that because of diversity of citizenship, federal common law should apply. Under federal common law, Erie could be liable for Tompkins's injuries.

1. Why had the decision in Swift v. Tyson prevented uniformity in the administration of state law?
2. After Erie, which court's procedural law must be applied in a diversity-of-citizenship case?