#32 · 2026-09-07 · Case
Erie Railroad Co. v. Tompkins
Erie Railroad Co. v. Tompkins rejected federal general common law. State substantive law, including state judicial decisions, governs relevant state-law issues in diversity cases. The case does not mean that state procedural rules invariably displace federal procedure.
Rule to remember
Erie requires federal courts deciding state-law issues in diversity cases to apply state substantive law, including state decisional law, rather than a federal general common law.
Key elements and checks
- Identify the substantive state-law issue.
- Apply the relevant state's law, including its highest court's decisions.
- Analyze procedural conflicts separately under the governing federal rules and later cases.
In the source’s words
“There is no federal general common law.”
Erie Railroad, 304 US 64, 78 (1938)
Erie does not eliminate specialized federal common law or require state procedure in every diversity action.