Sixth Circuit Holds That Garmon Doctrine Bars ERISA Fiduciary-Duty Claims That Necessarily Depend on Resolution of Disputed NLRA Obligations

In Rieth-Riley Construction Co., Inc. v. Trustees of the Operating Engineers’ Local 324 Fringe Benefit Funds, No. 25-1823, — F.4th —-, 2026 WL 915042 (6th Cir. Apr. 3, 2026), Plaintiff Rieth-Riley Construction Co., Inc. (“Rieth-Riley”) employed members of Operating Engineers’ Local 324 (“Local 324”) under a collective bargaining agreement (“CBA”) that ran through May 2, 2018. The CBA required Rieth-Riley to make contributions to several Local 324 fringe benefit funds (“Fringe Funds”) for each hour worked. After the CBA was mutually terminated to avoid its evergreen clause, Local 324 declined to negotiate a new CBA, and the Fringe Funds initially refused Rieth-Riley’s continued contributions—taking the position that the relationship was governed by Section 8(f) of the NLRA rather than Section 9(a). The Fringe Funds later reversed course and accepted contributions, but in September 2024 threatened to stop accepting them unless Rieth-Riley signed a written agreement binding it to the Funds’ governing documents. When Rieth-Riley declined, the Funds ceased accepting contributions as of October 1, 2024.

Rieth-Riley and three of its employees (collectively, “Plaintiffs”) filed separate suits in the Eastern District of Michigan under ERISA, alleging that the Fringe Funds’ Trustees breached their fiduciary duties of loyalty and prudence by refusing to accept Rieth-Riley’s contributions. Plaintiffs also contended that both Rieth-Riley and the Funds were independently obligated by the NLRA’s status quo doctrine—arising from Sections 8(a)(5) and 8(d)—to maintain contributions following CBA expiration while negotiations continued. Plaintiffs sought declaratory and injunctive relief, including a preliminary injunction ordering the Funds to resume accepting contributions. The district court dismissed the complaints for lack of subject matter jurisdiction under the Garmon doctrine, denied leave to amend, and denied the preliminary injunction requests. Plaintiffs appealed.

The Sixth Circuit affirmed on all grounds. The court reviewed the jurisdictional dismissal de novo. Applying San Diego Building Trades Council v. Garmon, 359 U.S. 236 (1959), the court explained that when an activity is “arguably subject” to Section 7 or Section 8 of the NLRA, courts—including federal courts—must defer to the primary jurisdiction of the National Labor Relations Board (“NLRB”). The court rejected Plaintiffs’ argument that Garmon is limited to state law claims, reaffirming that the doctrine extends to federal claims, including ERISA claims, where the conduct at issue arguably implicates the NLRA. The court also rejected the argument that Garmon could not apply because the NLRB lacks jurisdiction to adjudicate ERISA claims; the relevant question is whether the NLRA “arguably protects or prohibits” the conduct underlying the claim, not whether the federal claim itself could be brought before the Board.

The court then addressed the independent federal remedy exception, which permits federal courts to decide labor law questions that arise only as collateral issues in suits brought under independent federal remedies. The exception applies where a plaintiff can prove the claim “without ever having to establish a violation of the NLRA.” Pulte Homes, Inc. v. Laborers’ Int’l Union of N. Am., 648 F.3d 295, 300 (6th Cir. 2011). The court held the exception inapplicable here because Plaintiffs’ complaints expressly grounded the Trustees’ alleged ERISA violations in the Funds’ purported NLRA status quo obligation to accept contributions—not merely Rieth-Riley’s obligation to make them. Because Plaintiffs’ ERISA claims could succeed “only if” the Funds’ refusal violated the NLRA, the NLRA issues were not collateral but central to the claim. The court declined to address alternative grounds for dismissal.

The court affirmed denial of the preliminary injunction because Plaintiffs could not demonstrate a likelihood of success on the merits given the jurisdictional bar, and affirmed denial of leave to amend because the proposed amended complaint continued to require resolution of the same disputed NLRA question.

Judge Hermandorfer concurred in the judgment and wrote separately to flag significant structural concerns about Garmon that may warrant reconsideration in a future case. He noted that Garmon sits in tension with federal courts’ “virtually unflagging” obligation to exercise jurisdiction under 28 U.S.C. § 1331, that preemption does not typically deprive federal courts of subject matter jurisdiction, and that the doctrine’s application based on “arguable” rather than clear NLRA implications conflicts with the usual high bar for jurisdiction-stripping. He also raised the question whether Garmon’s deference to the Board survives Loper Bright Enterprises v. Raimondo, 603 U.S. 369 (2024), which requires courts to exercise independent judgment on statutory interpretation. Judge Hermandorfer nonetheless agreed that Garmon as currently interpreted by Sixth Circuit precedent required affirmance. He emphasized that the holding should not be read to foreclose ERISA claims that do not depend on establishing a disputed duty under the NLRA.