MBE Rules · Civil Procedure
Erie doctrine
Erie
The rule
In diversity cases, federal courts apply state SUBSTANTIVE law and federal PROCEDURAL law. If a Federal Rule of Civil Procedure is on point and valid under the Rules Enabling Act, it applies (Hanna). For unwritten federal practices conflicting with state law, apply the outcome-determinative / twin-aims test (Hanna, Byrd).
In plain English
In cases where people from different states are suing each other in federal court, the court uses the state's laws for important issues and federal rules for how the court process works.
Worked example
In a federal court case about a contract dispute between parties from different states, the court uses the state's law to decide if the contract is valid but follows federal rules for how evidence is presented in court.
Memory hook
ERIE: State substance, Fed procedure. Federal courts blend state law with federal rules in diversity cases.
The trap
Students think: Federal law always trumps. Wrong, because state substantive law governs in diversity. The actual test is whether it's outcome-determinative or affects forum shopping.
How examiners test it
The MBE loves: conflict between state and federal law in diversity. Setup often includes a federal rule on point. Trap: assume federal always wins. Remember, state law applies if substantive.
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