559 U.S. 393 (2010) (U.S. Supreme Court)
Shady Grove is a cornerstone Erie/Hanna decision on the interplay between Federal Rules of Civil Procedure and state law. It asks whether a federal court sitting in diversity (or under CAFA) may certify a class action under Rule 23 when the forum state would prohibit that class action.
Does Federal Rule of Civil Procedure 23 permit a federal court to certify a class action seeking statutory interest when the forum state's law (N.Y. CPLR § 901(b)) would bar such a class action, and if so, is Rule 23 valid under the Rules Enabling Act as applied?
Under the Erie/Hanna framework, a federal court sitting in diversity applies state substantive law and federal procedural law. When a Federal Rule of Civil Procedure directly answers the question in dispute and conflicts with state law, the court must apply the Federal Rule if, as applied, it is valid under the Rules Enabling Act—that is, it regulates procedure and does not abridge, enlarge, or modify any substantive right. Federal Rule of Civil Procedure 23 provides that a class action may be maintained if its prerequisites are satisfied; it governs class certification in federal court unless applying it would violate the Rules Enabling Act. On the controlling, narrowest ground (the concurrence), a state rule resists displacement only if it is so bound up with a state-created right or remedy that displacing it would effectively alter substantive rights.
Yes. Rule 23 directly answers whether a class action may be maintained and therefore governs. Applying Rule 23 here does not violate the Rules Enabling Act because it regulates procedure—the manner and means by which claims are aggregated—without altering substantive rights. Accordingly, the federal court may entertain the class action notwithstanding New York's CPLR § 901(b). The judgment of the Second Circuit was reversed.
Shady Grove confirms that when a valid Federal Rule of Civil Procedure squarely conflicts with a state procedural limitation, the Federal Rule governs in federal court. It is a teaching case for Erie, Hanna, and the Rules Enabling Act, particularly the two-step inquiry: (1) Is the Federal Rule on point and in conflict? (2) If so, is the Rule valid under the Enabling Act as applied? The controlling concurrence refines this by asking whether the state law is tightly bound to a substantive right. Practically, the case opened the door to federal class actions on claims that state courts would not aggregate, especially under CAFA. At the same time, its fractured opinions invite careful analysis: in later cases, courts often treat the concurrence's "bound up with substantive right" limitation as controlling, preserving room for some state rules—when truly substantive—to resist displacement.