This ruling has broad implications for Pennsylvania law, potentially rendering various state statutes and rules—including certificate of merit requirements, burden-shifting frameworks, presuit notice provisions, and expedited appeal rights—inapplicable in federal court.

In January, the U.S. Supreme Court resolved a circuit split on a topic that has closely involved Pennsylvania since Erie Railroad v. Tompkins, 304 U.S. 64 (1938) was decided nearly 90 years ago: the choice between federal and state law for a federal court sitting in diversity. Berk v. Choy, 607 U.S. 187 (2026), held that a Delaware statute imposing an “affidavit of merit” requirement in medical malpractice suits does not apply in federal diversity cases.

The court reached this conclusion not because the Delaware statute itself is procedural, but because a Federal Rule of Civil Procedure applies, meaning the court “bypasses Erie’s inquiry altogether,” citing Hanna v. Plumer, 380 U.S. 460, 469–74 (“a valid Rule of Civil Procedure displaces contrary state law even if the state law would qualify as substantive under Erie’s test”). Specifically, Federal Rule of Civil Procedure 8 sets the pleading standard, as reinforced by Rule 12, and therefore “answers the question in dispute.” see Berk, 607 U.S. at 192, citing Shady Grove Orthopedic Associates v. Allstate Insurance, 559 U.S. 393, 398 (2010). Any statute that imposes additional pleading requirements—such as the expert affidavit requirement—conflicts with those rules and cannot be applied in federal court.

The direct effects of Berk on the federal applicability of Pennsylvania law were immediately apparent. In DiFraia v. Ransom, 171 F.4th 622, 633 (3d Cir. 2026), the U.S. Court of Appeals for the Third Circuit held that Pennsylvania Rule 1042.3, requiring a certificate of merit in professional liability cases, does not apply in federal cases, overturning Liggon-Redding v. Estate of Sugarman, 659 F.3d 258, 264–65 (3d Cir. 2011).

Thus far, Pennsylvania federal district court decisions applying Berk have primarily focused on Pa.R.Civ.P. 1042.3, but Berk is likely to have broader implications on litigants’ ability to rely on various other Pennsylvania statutes and rules in federal courts—effects which are already being explored in other states.

In Earehart v. Peerless Chain, No. 2:25-CV-13340, slip op. (E.D. Mich. May 14, 2026), for example, the Eastern District of Michigan applied Berk’s reasoning to the issue of pleading requirements for nonparty fault defenses. Pennsylvania Rule 1019 also differs slightly from Federal Rule of Civil Procedure 9, insofar as it requires specification as to whether referenced agreements are oral or written and requires any material writings to be attached to the pleadings. Like the Michigan rule (and the affidavit of merit at issue in Berk), these Pennsylvania requirements would likely be found inapplicable in federal court because Federal Rule of Civil Procedure 8 is on point.

Anti-SLAPP statutes also provide some clues as to potential expansions of Berk’s holding. State Anti-SLAPP laws have been the subject of extensive Erie analysis, and there remains a circuit split as to whether these statutes (especially their early dismissal provisions) can be applied in federal diversity cases. The First and Ninth circuits apply them, while several other circuits have disallowed their application because the statutes impose evidentiary burdens or burden-shifting provisions that differ from Federal Rules 12 and 56, allow for potential early resolution of claims, and sometimes stay discovery when certain conditions are met. Compare Godin v. Schencks, 629 F.3d 79 (1st Cir. 2010) (allowing application), and Gunn v. Drage, 65 F.4th 1109, 1119 (9th Cir. 2023) (“we have repeatedly affirmed the applicability of California's anti-SLAPP statute in diversity cases”), with La Liberte v. Reid, 966 F.3d 79 (2d Cir. 2020) (California’s anti-SLAPP statute inapplicable in federal court), Carbone v. Cable News Network, 910 F.3d 1345 (11th Cir. 2018) (same as to Georgia’s anti-SLAPP statute), Klocke v. Watson, 936 F.3d 240 (5th Cir. 2019) (same as to Texas's anti-SLAPP statute), and Abbas v. Foreign Policy Group, 783 F.3d 1328 (D.C. Cir. 2015) (motion to dismiss provision of D.C.’s anti-SLAPP statute cannot apply in federal court because it “answers the same question” as Rules 12 and 56: when can a case be dismissed before trial?).

Though the Third Circuit has yet to weigh in, district court decisions in Pennsylvania primarily fall into the second camp. See Salaam v. Trump, 350 F.R.D. 14 (E.D. Pa. 2025) and Jakes v. Youngblood, 782 F.Supp.3d 210 (W.D. Pa. 2025). But see Lento Law Group v. Estrada, No. 25-2763, slip op. (E.D. Pa. July 21, 2026). Some commentators have speculated that Berk foretells a similar decision in the anti-SLAPP context, disallowing the application of these statutes in federal diversity cases nationwide. See, e.g. Travis Chance and Sean Cuff, "Supreme Court Ruling Signals Trouble Ahead for Anti-SLAPP Statutes in Federal Court," JD Supra (Jan. 21, 2026).

Berk could also support an argument that other similar statutes should not be applied in federal cases—particularly statutes with heightened burdens or burden-shifting frameworks and those that provide avenues for pretrial resolution. In Pennsylvania, examples may include the Pennsylvania Human Relations Act, 43 P.S. Sections 951–963, the Pennsylvania Whistleblower Law, 43 P.S. Sections 1421–1428, and civil asset forfeiture proceedings under 42 Pa.C.S. Section 5805(j)—all of which employ some type of burden-shifting framework. Berk may also apply to preclude the application of Pennsylvania statutes that employ heightened evidentiary burdens, such as the Uniform Voidable Transactions Act, 12 Pa.C.S. Section 5104(c).

Berk could also arguably preclude the application in federal court of other statutes and rules that provide avenues for pretrial resolution, such as the in forma pauperis dismissal rule under Pa.R.Civ.P. 240(j) (authorizing courts to dismiss frivolous actions filed alongside poverty petitions) or the prisoner litigation statute, 42 Pa.C.S. Section 6602 (mandating early dismissal of frivolous or meritless claims).

Presuit notice provisions—which are often considered substantive under Erie, particularly when the failure to provide notice can bar suit—are another potential target. Berk emphasizes that a statute need not dictate the contents of a complaint itself to constitute an improper threshold requirement beyond the provisions of Fed. R. Civ. P. 8(a). See Berk, 607 U.S. at 194–95 (“we think it is fair to infer that by specifying what information about the merits is required in the ‘pleading,’ Rule 8 excludes the possibility of requiring even more information on the same topic—whether in the ‘pleading’ itself or on a separate sheet of paper …”). In support of this point, Berk further cites Jones v. Bock, 549 U.S. 199 (2007), in which the Supreme Court rejected the requirement that prisoners “attach proof of exhaustion …to their complaints” as inconsistent with Rule 8. The timing of a requirement for additional information is also not dispositive of whether such a requirement constitutes a threshold pleading requirement. See Redman v. Irwin, No. 1:24-CV-00310-RAL, slip op. (W.D. Pa. Mar. 12, 2026) (reasoning that a certificate of merit due 60 days after the filing of the complaint was still “a threshold pleading obligation beyond the ‘short and plain statement’ required by Rule 8(a).”)

In short, threshold requirements—even those relating to separate documents due at different times—run afoul of Rule 8 under Berk. Accordingly, notice requirements in various statutes might arguably conflict with Rule 8 and be inapplicable in federal cases—for example, the six-month notice period for actions against governmental units under 42 Pa.C.S. Section 5522.

Additionally, statutes that provide for expedited or immediate appeals might be affected, insofar as they differ from federal rules governing the appeals process. This could potentially affect appeal rights in cases involving Pennsylvania’s Anti-SLAPP statute, 42 Pa.C.S. Section 8340.17, and in eminent domain proceedings under 42 Pa.C.S. Section 702.1.

Ultimately, Berk makes clear that any state rule or statute that addresses an area also covered by the federal rules must yield to the applicable federal rule, even if it is not impossible to comply with both, and even if the state rule is substantive. While this is not new, Berk represents an extension of this concept via a clear pronunciation that Rule 8 regulates beyond the complaint itself, insofar as it precludes the application of pre-suit certificate of merit requirements in federal court. How much further the courts will take this concept remains to be seen, but Berk at least opens the door to a broad range of Pennsylvania statutes and rules being rendered toothless in federal court.

The broad range of statutes and rules to which Berk’s federal prohibition might apply should be considered when weighing whether to remove a case to federal court, whether to contest removal, and what parties to sue.

Michaela L. Cloutier is an associate at Duane Morris. Note: some of the points in the article arise from discussions with Robert L. Byer, a partner in the appellate practice of the firm.

Reprinted with permission from The Legal Intelligencer, © ALM Media Properties LLC. All rights reserved.