Also known as:outcome determination test · outcome-determination tests · outcome-determinative test
Written by attorneys · grounded in primary & secondary sources — see below
A test applied in diversity cases to classify state rules as substantive or procedural for Erie purposes. An issue qualifies as substantive when disregarding the state rule would substantially affect the litigation outcome and produce a result in federal court materially different from the result a state court would reach.
Sources & Authorities· 1 primary source
Select any source to read its text and confirm it supports the definition.
Cases
Casebooks
How it applies
Common Examples
2
Statute of Limitations in Diversity Suit
Opal Okoro sued her brokerage firm in federal court under diversity jurisdiction after discovering unsuitable investments years earlier. State law applied a discovery rule that tolled the limitations period until reasonable discovery. The firm moved to dismiss under a strict federal accrual rule. The court applied the outcome-determination test and followed the state discovery rule because using the federal rule would bar the claim in federal court while a state court would allow it to proceed.
Tolling Provision for Concealment
Olivia Owens filed a medical malpractice action in federal court after a surgical instrument was left inside her during an operation. State law tolled the two-year limitations period for up to three years when providers concealed the error through nondisclosure. The hospital moved to dismiss under a stricter federal equitable tolling standard. The court applied the outcome-determination test and used the state tolling rule because ignoring it would dismiss a claim that state courts would entertain.
Common questions
Frequently Asked
4
How does the outcome-determination test decide whether a state statute of limitations is substantive?+
The test asks whether disregarding the state rule would produce a materially different result in federal court than in state court. Statutes of limitations and their tolling provisions control whether a claim can proceed at all. Because applying a different federal rule would allow or bar claims differently than state law, the test classifies them as substantive.
Supporting sources
What happens when a federal court ignores an outcome-determinative state tolling rule?+
The federal court would reach a result that state courts would reject, violating the Erie command that the outcome should not turn on the choice of forum. The test therefore requires application of the state rule to prevent forum shopping and inequitable administration of the laws.
Supporting sources
Does the outcome-determination test apply only when the choice of law will change the final judgment?+
No. The test focuses on whether ignoring state law would materially alter the litigation result, not on whether the difference happens to decide the ultimate winner. A rule that decides whether the claim survives at all satisfies the test even if other defenses remain available.
Supporting sources
Why must federal courts apply state concealment-tolling statutes under the outcome-determination test?+
Concealment tolling extends the period during which suit may be brought and directly determines whether recovery remains available. Disregarding the state provision would bar claims that state courts would allow, creating the precise outcome disparity the test seeks to avoid.
Supporting sources
Civil ProcedureLaw applied by federal courts · State law in federal courtUBEFoundational