Erie Doctrine (E=state law on substantive matters, R=federal rules on procedure, I=Identical outcome test, E=Equity and fairness) = State law on substance · Federal law on procedure
Substance vs. procedureSubstantive (state): elements of claims, statutes of limitations, standards of liability. Procedural (federal): pleading standards, discovery rules, trial procedures.
Outcome determinativeGuaranty Trust test: would applying federal vs. state law significantly affect the outcome? If yes → substantive → apply state law.
Hanna v. PlumerIf a Federal Rule of Civil Procedure directly conflicts with state law, the FRCP governs if it's valid under the Rules Enabling Act.