Tompkins (P) was walking in a well-trodden footpath next to some railroad tracks. An Erie Railroad (D) train came by and P was struck and injured by a black object that looked like an open door sticking out from one of the rail cars. The accident occurred in Pennsylvania. Under Pennsylvania case law, P would be considered a trespasser with no chance of recovery unless there was a showing that D's conduct was wanton and willful. Under the law recognized in federal courts, P would have been regarded as a licensee and could recover with a showing of ordinary negligence. P sued D in Federal Court in New York based on diversity jurisdiction because D was a New York corporation. P then argued that under Swift, Federal courts must follow only state statutory laws and not state judge made laws. Under that general statutory law, a railroad owed a duty of ordinary care to pedestrians. D argued under the Federal Rules of Decision Act, which states that laws of the states shall be regarded as rules of decision in federal civil cases unless otherwise provided by the Constitution or federal statute, for Pennsylvania common law wherein P would be a trespasser with only the duty of D to avoid wanton or willful negligence. P got a judgment for $30,000 as the court agreed with him. D appealed and the decision was affirmed at the federal circuit court. The Supreme Court granted review.