Docket 24-440
Berk v. Choy
DecidedJan 20, 2026
9-0unanimous decision
Source: CourtListener.
Delaware's malpractice-affidavit filing rule doesn't apply to lawsuits filed in federal court
What it does
The Court holds that Delaware's requirement that medical malpractice plaintiffs attach a medical professional's affidavit of merit to their complaint cannot be enforced in federal court because it conflicts with Federal Rule of Civil Procedure 8, which only requires a short plain statement of the claim. Because Rule 8 is a valid procedural rule under the Rules Enabling Act, it displaces the contrary state law even though the state law would otherwise apply under ordinary state-law rules in diversity cases.
Who benefits
Medical malpractice plaintiffs who sue doctors or hospitals in federal court based on diversity jurisdiction, since they no longer need to obtain and file a medical expert's affidavit before their case can proceed.
Who is affected
Doctors, hospitals, and other medical malpractice defendants sued in federal court, who lose an early screening mechanism that Delaware and similar states created to filter out weak malpractice claims before litigation costs accrue.
Practical impact
Medical malpractice plaintiffs suing in federal diversity court in Delaware and similarly situated states no longer need to secure a supporting medical affidavit before or shortly after filing suit; their complaints will be evaluated only under the plausibility pleading standard. Defendants seeking to test the merits of weak claims must instead wait for discovery and use summary judgment motions under Rule 56, rather than relying on an early affidavit-based screening dismissal.
Majority reasoning
The majority explained that when a plaintiff sues on a state-law claim in federal court, courts must first ask whether a Federal Rule of Civil Procedure answers the disputed question; if so, that rule governs unless it exceeds Congress's rulemaking authority. The Court found that Rule 8's requirement of only "a short and plain statement of the claim" implicitly but clearly means that evidence, like an affidavit, cannot also be demanded at the pleading stage, and Rule 12 reinforces this by barring courts from considering matters outside the pleadings when deciding whether a claim was adequately stated. The majority rejected defendants' attempts to recharacterize Delaware's law as merely an evidentiary requirement enforceable through separate mechanisms, noting that Rule 56 (summary judgment) already provides the process for testing a plaintiff's evidence and defendants could not fit their proposal into any existing Federal Rule. The Court also rejected the argument that Rule 11's affidavit proviso incorporates state laws like Delaware's, because Rule 11 concerns attorney certifications, not third-party medical affidavits. Finally, the majority held that Rule 8 is procedural rather than substantive under the Rules Enabling Act, following Sibbach's test of whether a rule "really regulates procedure," and explicitly rejected considering whether the displaced state law is itself substantive. Responding to the concurrence's critique that its negative inference reads too much into Rule 8, the majority noted in footnote 2 that drawing negative inferences from text is a standard interpretive tool, and that the concurrence's own Rule 3 analysis relies on an analogous inference.
Constitutional question
When a state law and a Federal Rule of Civil Procedure both address what a plaintiff must submit at the start of a lawsuit, does the state law or the federal rule control in a federal court case based on diversity jurisdiction?