Tompkins was a citizen of Pennsylvania. While walking on a railroad footpath in that state, he was struck by an object protruding from a passing freight train owned by the Erie Railroad Company, a New York corporation. Tompkins, by virtue of diversity of citizenship, filed a negligence suit against Erie in a New York federal court. Erie argued for the application of Pennsylvania common law, in which case Tompkins would have been treated as a trespasser. Tompkins argued that the absence of a Pennsylvania statute addressing the topic meant that federal common law had to be applied to the case. Should the federal court apply the relevant Pennsylvania state law, or should the court be free to exercise its independent judgment about what the common law of the state is or should be?