Berk v. Choy

607 U. S. 187 (2026) · 1/20/26

Delaware law requiring a plaintiff suing for medical malpractice to provide an affidavit from a medical professional attesting to the suit’s merit, Del. Code, Tit. 18, §6853(a)(1), conflicts with a valid Federal Rule of Civil Procedure and does not apply in federal court.

Delaware law provides that a plaintiff may not sue for medical malpractice unless a medical professional attests to the suit's merit in an “affidavit of merit” that “accompanie[s]” the plaintiff 's complaint. Del. Code, Tit. 18, § 6853(a)(1). Petitioner Harold Berk sued Dr. Wilson Choy and Beebe Medical Center in federal court for medical malpractice under Delaware law, but failed to provide the affidavit required by § 6853. Berk argued that § 6853 is not enforceable in federal court because it is displaced by the Federal Rules of Civil Procedure. The District Court dismissed Berk's lawsuit…

Held: Delaware's affidavit law does not apply in federal court. Pp. 191–200. (a) When a plaintiff brings a state-law claim in federal court, the court faces a choice-of-law problem: whether to apply state or federal law. The Rules of Decision Act directs federal courts to apply state substantive law unless the Constitution, a treaty, or a statute otherwise requires or provides. 28 U. S. C. § 1652. The Rules Enabling Act, which authorizes the Supreme Court to adopt uniform rules of procedure for district courts, provides for the application of federal law. § 2072(a). So, when a valid Federal…