Also known as: rules of decision
Written by attorneys · grounded in primary & secondary sources — see below
A rule, statute, body of law, or prior decision that provides the basis for deciding or adjudicating a case. In federal civil actions it identifies the substantive law that governs a claim or defense when state law applies under the Erie doctrine.
Roger Ramirez sued Redwood Bank in federal court under diversity jurisdiction after a disputed account transfer. The bank called an elderly depositor as a witness whose competency was questioned under state guardianship rules. Because state law supplied the rule of decision on the contract claim, the court applied the state competency standard rather than the federal default that every person is competent.
Rajesh Rao purchased land in one state from Regal Apparel under a contract formed in another state. A third party claimed an easement based on long use. The court identified the rule of decision for the property interest by weighing the most significant relationship factors among the states involved.
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Raphael Rivera brought a state-law tort claim in federal court against Rhea Reynolds. During discovery Reynolds sought to compel production of an internal memo. Because state law supplied the rule of decision on the claim, the court applied state privilege law to decide whether the memo was protected.
Ronald Reed sued Redline Automotive in diversity for a product defect. Redline introduced a notarized acceptance certificate that under state law raised a presumption shifting the burden of persuasion. The federal court applied the state presumption because state law supplied the rule of decision on the claim.
Rosa Ruiz's family challenged a state hospital's refusal to withdraw life support under a state evidentiary standard requiring clear and convincing proof of prior wishes. The Supreme Court examined whether the Constitution barred the state from choosing that particular rule of decision for the dispute.
A worker injured on a rural cooperative's project sued in federal court under diversity. The cooperative sought to have the judge decide a factual issue that state law assigned to the jury. The court weighed the strong federal policy favoring jury resolution against the state rule of decision to avoid outcome differences between state and federal forums.
State law supplies the rule of decision in a civil case when the claim or defense arises under state substantive law, such as in diversity actions or when a federal rule expressly directs application of state law on competency, privilege, or presumptions.
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Under Federal Rule of Evidence 601 every person is competent unless the rules provide otherwise, but when state law supplies the rule of decision the court applies the state competency standard instead.
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The rule of decision for interests in a thing is supplied by the law of the state with the most significant relationship to the thing and the parties, guided by the factors in Restatement section 6.
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No. When venue was proper in the original district the transferee court must apply the same state law, including choice-of-law rules, that the transferor court would have applied.
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…except where the Constitution, treaties, or statutes of the United States otherwise require or provide, shall be regarded as rules of decision in trials at common law, in the courts of the United States, in cases where they apply." Because of the importance of the question whether the federal court was free to disregard the…