The Erie Doctrine determines whether a federal court must apply federal law or state law when hearing a case under diversity jurisdiction. It is one of the most heavily tested topics in Civil Procedure.
The core rule is that federal courts must apply state substantive law and federal procedural law.
Understanding how to distinguish between substantive and procedural law is critical for answering Erie questions correctly on the bar exam.
What Is the Erie Doctrine?
The Erie Doctrine comes from the Supreme Court’s decision in Erie Railroad v. Tompkins. It requires federal courts sitting in diversity jurisdiction to apply state law in certain circumstances.
The purpose of the doctrine is to prevent forum shopping and ensure consistent outcomes between state and federal courts.
Basic Erie Rule
A federal court must apply:
State substantive law
Federal procedural law
This distinction is the foundation of all Erie analysis.
What Counts as Substantive Law?
Substantive law includes rules that affect the outcome of the case.
Examples include:
Elements of claims and defenses
Statutes of limitations
Rules of damages
Choice of law rules
If applying federal law instead of state law would change the outcome of the case, the rule is likely substantive.
What Counts as Procedural Law?
Procedural law governs how the litigation process works.
Examples include:
Federal Rules of Civil Procedure
Rules governing pleadings and motions
Discovery procedures
Federal courts generally apply federal procedural rules, even in diversity cases.
How Erie Is Tested on the Bar Exam
Bar exam questions often test how to resolve conflicts between federal and state law.
One common scenario is when a Federal Rule of Civil Procedure directly conflicts with a state rule. In that case, the federal rule usually applies if it is valid under the Rules Enabling Act.
Another common issue is when there is no direct conflict. In that situation, courts apply tests such as outcome determinative analysis and consideration of forum shopping.
Outcome Determinative Test
If applying federal law instead of state law would significantly affect the outcome of the case, the court should apply state law.
This test helps ensure that the result in federal court is similar to what it would be in state court.
Forum Shopping and Inequitable Administration
Courts also consider whether applying federal law would encourage forum shopping or lead to unfair differences between litigants.
If so, state law should be applied.
Common Exam Traps
Students often assume that federal courts always apply federal law. This is incorrect in diversity cases.
Another common mistake is failing to recognize when a rule is outcome determinative.
A third trap is forgetting that valid Federal Rules of Civil Procedure generally control when there is a direct conflict.
Why This Matters
The Erie Doctrine is frequently tested because it requires careful analysis and forces students to apply multiple rules at once.
Mastering Erie allows you to navigate conflicts between federal and state law and avoid common exam traps that lead to incorrect answers.
Procedural vs Substantive Due Process (compare frameworks)