Case brief summary
Federal courts hearing lawsuits between citizens of different states must apply the actual law of the state involved, including decisions by that state's own courts, instead of making up their own general legal rules.
Facts
Tompkins was hit by a train while walking beside railroad tracks in Pennsylvania. He sued the railroad in federal court in New York, raising the question of whether Pennsylvania's rules on duties to walkers should apply.
Procedural history
A jury awarded Tompkins $30,000. The appeals court upheld this, saying general legal principles applied instead of Pennsylvania court rulings. The Supreme Court agreed to hear the case.
Issue
Should federal courts, when deciding cases based only on the parties being from different states, be free to create their own general legal rules instead of following the law as declared by the state's own courts?
Holding
Federal courts must follow state law, including unwritten court-made law, unless the Constitution or federal statutes say otherwise. There is no separate general federal common law to use instead.
Reasoning
Letting people sue in federal court just to get better results than in state court was unfair and didn't bring uniformity. The old rule misread an 1789 law and wrongly took power belonging to the states.
Opinions
Majority (Brandeis): Federal courts must apply state law, including state court decisions, because there is no general federal common law and doing otherwise invades states rights.
Concurrences (Reed): Agrees Swift v. Tyson should be overturned but says this only required reinterpreting the statute, not declaring the old approach unconstitutional.
Dissent (Butler, joined by McReynolds): Argues the Court should not have decided a constitutional question not raised by the parties and would reverse simply because the evidence showed Tompkins was contributorily negligent.