1. Introduction

This Sixth Circuit rehearing order arises from an antitrust dispute about allergy testing and allergen immunotherapy services in Tennessee. The plaintiff-appellant, United Biologics, LLC (doing business as United Allergy Services, “United Allergy”), alleged that an incumbent provider, Allergy Associates, P.A., and several insurers (including Amerigroup Tennessee, Inc.) orchestrated conduct amounting to a group boycott that foreclosed reimbursement for services provided through arrangements between United Allergy and primary care physicians (“PCPs”).

The First Amended Complaint alleged that Allergy Associates held a dominant market position (about 70%) and that United Allergy attempted to create new competition by supplying staffing, equipment, and supplies so PCPs could provide similar services. The alleged scheme: Allergy Associates purportedly made unfounded fraud accusations to insurers and encouraged the insurers to deny reimbursement to PCPs working with United Allergy—driving the venture’s participants from the market.

The key legal issue, however, became not whether the alleged conduct plausibly violated the antitrust laws, but whether United Allergy had antitrust standing—specifically, whether the “directness” requirement of proximate causation (associated with Illinois Brick) barred an upstream supplier/service provider from suing insurers alleged to be antitrust-violating purchasers (a monopsony-side theory).

2. Summary of the Opinion (Rehearing Denial and Published Statements)

The court denied rehearing en banc because no judge requested a vote. The published writings clarify the fault line:

• Judge Bush’s statement agrees the panel’s approach is a reasonable application of Supreme Court precedent, but warns it may be over-formalistic and unduly expansive in applying Illinois Brick Co. v. Illinois to (i) group-boycott allegations and (ii) business arrangements that function as joint ventures. He also highlights a separate question: whether Illinois Brick should bar suits for injunctive relief under Clayton Act § 16.
• Judge Murphy’s concurrence asserts the panel’s holding is straightforward under Apple Inc. v. Pepper and Illinois Brick: direct sellers (like direct purchasers) may sue; indirect sellers may not. He rejects a boycott/overcharge distinction, rejects a “joint venture” carve-out as inconsistent with the bright-line rule, and treats the injunction point as forfeited because it was not timely raised.

Bottom line: the en banc court did not revisit the panel’s conclusion that United Allergy—positioned upstream from the allegedly antitrust-violating insurers—lacked antitrust standing under Illinois Brick’s directness principles as applied to indirect sellers.

3. Analysis

3.1. Precedents Cited (and How They Shaped the Outcome)

Illinois Brick Co. v. Illinois is the centerpiece. It read Clayton Act § 4’s “by reason of” language to impose a directness limitation: only the direct purchaser may recover damages for overcharges; indirect purchasers are barred. In this case, the question is the “mirror image”—whether the same directness rule bars indirect sellers (those upstream from an antitrust-violating buyer/monopsonist). Judge Murphy treats that extension as settled, and the panel had already stated that “the circuit courts all agree” on it.

Apple Inc. v. Pepper supplies the modern framing: Illinois Brick is a “bright-line rule” of proximate causation. Judge Murphy relies on Apple to insist the rule is categorical: “direct purchasers” (and, by analogy, direct sellers) may sue; “indirect purchasers” (and indirect sellers) may not. Judge Bush counters that Apple can be read as holding direct purchasers may always sue when there is no intermediary, without necessarily converting the doctrine into a strict “contractual privity” requirement that defeats all non-privity plaintiffs.

Hanover Shoe, Inc. v. United Shoe Machinery Corp. matters because it complements Illinois Brick: direct purchasers can recover without reduction for amounts “passed on.” Judge Murphy uses that complementarity to argue that allowing United Allergy’s indirect-seller suit risks double recovery if directly injured physicians can recover “the entire undercharge” (unreimbursed amounts) while upstream entities also claim damages. The implication: the Court’s remedial architecture is built around allocating damages to the direct tier.

Kansas v. UtiliCorp United, Inc. reinforces anti-exception logic. Even where economic reality suggested end consumers bore “100 percent” of overcharges (regulated utilities), the Supreme Court refused to “litigate a series of exceptions.” Judge Murphy invokes this as a warning against a “joint venture” exception that could erode the bright-line rule into fact-intensive disputes.

Blue Shield of Virginia v. McCready is the most important counterweight raised by Judge Bush. McCready recognized standing for a plaintiff whose injury was “inextricably intertwined” with the conspiracy’s target and “clearly foreseeable.” Judge Bush uses McCready to argue that a joint-venture participant can be harmed as a necessary step of the scheme, even absent direct contractual privity with the defendants. Judge Murphy responds that (i) this case does not resemble Apple or McCready in market structure and (ii) foreseeability cannot replace Illinois Brick’s directness requirement.

Associated Gen. Contractors v. Cal. State Council, Holmes v. Sec. Inv. Prot. Corp., and Hemi Grp., LLC v. City of New York support Judge Murphy’s insistence that proximate cause has multiple dimensions and that “directness” is independent from “foreseeability.” Even “intended victims” may sometimes be denied standing when the chain is too remote. Lexmark Int'l, Inc. v. Static Control Components, Inc. supplies the general federal-cause-of-action principle that proximate cause bars harms “purely derivative” of injury to a third party.

These cases inform the policy debate, not the dispositive holding. Judge Bush emphasizes the Supreme Court’s functional approach in antitrust substance (for example, Am. Needle, Inc. v. Nat'l Football League and the anti-formalism language in Leegin Creative Leather Prods., Inc. v. PSKS, Inc. and Cont'l T. V., Inc. v. GTE Sylvania). His point: defining “indirect seller” in joint-venture settings should be functional, not purely transactional.

Judge Bush also uses group-boycott authorities and competitor-entry narratives (citing Nw. Wholesale Stationers, Inc. v. Pac. Stationery & Printing Co. and out-of-circuit cases like PLS.Com, LLC v. Nat'l Ass'n of Realtors (quoting Smith v. Pro Football, Inc.)) to stress that foreclosure from essential trading relationships is classic boycott harm—often aimed at excluding new entrants.

A notable prospective issue is whether Illinois Brick limits only damages under Clayton Act § 4 (15 U.S.C. § 15(a)) or also affects injunction claims under Clayton Act § 16 (15 U.S.C. § 26). Judge Bush argues § 16’s text (“threatened loss or damage”) and remedial structure reduce concerns about duplicative recovery, and cites circuits that have declined to apply Illinois Brick to injunction standing (for example, Mosaic Health, Inc. v. Sanofi-Aventis U.S., LLC, Or. Laborers-Emps. Health & Welfare Tr. Fund v. Philip Morris Inc., and McCarthy v. Recordex Serv., Inc.). Judge Murphy does not reach the merits, characterizing the issue as forfeited.

3.2. Legal Reasoning

Although the en banc court did not issue a merits opinion, the published writings reveal the operative reasoning:

• Statutory anchor: Clayton Act § 4 provides a damages cause of action to those injured “by reason of” antitrust violations (15 U.S.C. § 15(a)). The phrase is treated as importing proximate-cause limits.
• Bright-line directness: Illinois Brick, as reaffirmed in Apple Inc. v. Pepper, imposes a categorical rule allocating damages claims to the direct tier in the distribution (or purchasing) chain.
• Symmetry (buyers and sellers): The doctrine applies both to direct purchasers (suing sellers) and direct sellers (suing buyers/monopsonists). Hence, a plaintiff that sells to an intermediary that sells to the alleged monopsonist is an “indirect seller.”
• Resistance to exceptions: Judge Murphy emphasizes Supreme Court reluctance to carve exceptions (invoking Kansas v. UtiliCorp United, Inc.), warning that “joint venture” characterization could become a pliable way around the doctrine.
• Competing framework (Bush): Judge Bush’s proposed narrowing is conceptual rather than a stated “exception”: treat functionally integrated joint-venture participants as effectively a single direct market participant for Illinois Brick purposes, especially in boycott settings where damages may be less speculative than passed-on overcharge calculations.

3.3. Impact

Within the Sixth Circuit, the practical signal is restrictive: upstream participants who enable downstream providers to deliver services (through staffing, equipment, and supplies) will face significant standing hurdles when the immediate contracting parties with the alleged antitrust violators are those downstream providers.

Joint-venture structuring pressure: Judge Bush highlights a market-entry concern: if a challenger must collaborate with clinical actors to provide regulated services, a rigid “indirect seller” frame may leave some venture participants unable to sue even when allegedly targeted. This may shift how entrants structure contracts and billing flows—potentially encouraging formal privity engineering rather than economically efficient organization.

Remedy bifurcation remains unresolved: the writings sharpen, but do not decide, whether indirect entities might still pursue injunctive relief under § 16 notwithstanding Illinois Brick. Judge Murphy’s forfeiture stance keeps the Sixth Circuit’s merits position formally open, while Judge Bush’s discussion flags an emerging inter-circuit debate.

Supreme Court invitation: both writings, in different ways, frame this as a candidate for high-court clarification: how Illinois Brick applies to modern health-care markets with integrated service delivery, boycott allegations, and mixed vertical/horizontal features.

4. Complex Concepts Simplified

• Antitrust standing (not Article III standing): a set of limits on who may sue for antitrust damages—focused on whether the plaintiff’s harm is the right type (antitrust injury) and sufficiently direct (proximate cause).
• Illinois Brick rule: generally confines damages claims to the party that dealt directly with the antitrust violator in the chain (direct purchaser; and by extension, direct seller). It aims to avoid complex tracing of who ultimately bore an overcharge/undercharge and to prevent duplicative recovery.
• Direct seller vs. indirect seller: a direct seller sells to the alleged antitrust-violating buyer; an indirect seller sells to someone who sells to that buyer—making the indirect seller “two or more steps removed.”
• Group boycott: coordinated refusal to deal (or coordinated denial of access to necessary trading partners), sometimes treated as per se unlawful depending on structure and market power, and often alleged to exclude entrants.
• Monopsony: market power on the buying side (a powerful purchaser suppressing prices or excluding sellers), conceptually parallel to monopoly power on the selling side (the writings cite Weyerhaeuser Co. v. Ross-Simmons Hardwood Lumber Co.).
• Proximate cause—directness vs. foreseeability: foreseeability asks whether the harm was predictable; directness asks whether the injury is too remote because it depends on harm to someone else first. The debate here is whether foreseeability and “inextricably intertwined” harms (from Blue Shield of Virginia v. McCready) can coexist with Illinois Brick’s bright-line directness rule.
• Damages vs. injunctions: damages risk duplicative recovery; injunctions typically do not. That difference may matter under Clayton Act § 16, which authorizes suits to prevent “threatened loss or damage.”

5. Conclusion

The Sixth Circuit’s denial of rehearing en banc leaves standing doctrine where the panel placed it: Illinois Brick’s directness limitation—reinforced by Apple Inc. v. Pepper—bars damages claims by upstream entities that are “two or more steps removed” from the alleged antitrust violators, even when the alleged conduct resembles a group boycott in a health-care reimbursement ecosystem.

Judge Bush’s statement crystallizes the principal critique: applying an overcharge-oriented, bright-line doctrine to joint-venture-like service delivery and boycott allegations may be too formalistic and may underprotect market entry. Judge Murphy’s concurrence crystallizes the countervailing principle: lower courts must follow the Supreme Court’s chosen bright-line approach and resist case-specific exceptions that threaten administrability and coherent remedies.

The most consequential forward-looking question flagged—but not resolved on the merits—is whether (and how) Illinois Brick should constrain claims for injunctive relief under Clayton Act § 16.