Can a competitor’s legal conduct be aggregated to form a valid antitrust case?
The Supreme Court has been asked to review the Fourth Circuit’s Duke Energy Carolinas, LLC v. NTE Carolinas II opinion endorsing the controversial “monopoly broth” theory, which permits the aggregation of independently lawful business practices into a single antitrust violation.
Duke Energy, along with its affiliates, has asked the Supreme Court to overturn the Fourth Circuit opinion, arguing it dramatically and inappropriately expands antitrust liability under Section 2 of the Sherman Act. The petition focuses on three central points:
Conflict with Supreme Court Precedent: Duke Energy argues that the Fourth Circuit’s adoption of the monopoly broth theory directly contradicts established Supreme Court rulings. In cases like Pacific Bell v. linkLine and Brooke Group v. Brown & Williamson Tobacco Corp., the Court made clear that lawful conduct cannot be transformed into anticompetitive behavior through aggregation, the petition states. Duke contends that the Fourth Circuit’s approach ignores the requirement that at least one act must be independently anticompetitive to sustain liability.
Creation of Legal Uncertainty: The petition warns that the decision generates unpredictability for businesses, making it difficult to discern when competitive conduct might trigger liability. Duke Energy asserts that this uncertainty may chill innovation and deter procompetitive behavior, undermining the intent of antitrust laws.
Potential Nationwide Impact: According to the petitioners, the Fourth Circuit’s decision could set a dangerous national precedent. Because the Clayton Act’s venue rules allow broad choice of forum, antitrust plaintiffs nationwide could increasingly file cases in the Fourth Circuit, exposing businesses to an expansive and fact-bound interpretation of antitrust liability. Duke warns that this could stifle competition and harm consumers across industries.
Duke Energy says the Fourth Circuit dismissed the “0 + 0 = 0” principle—namely, that the sum of lawful acts cannot be unlawful—and instead allowed for the aggregation of conduct as part of a coordinated anticompetitive scheme. The company insists that such reasoning disregards the Supreme Court’s clear rules for evaluating business practices, threatening to introduce confusion and uncertainty into antitrust enforcement.
Industry Groups Warn of Chilling Effects
A coalition of technology and communications industry groups—including the Computer & Communications Industry Association, ACT | The App Association, and NetChoice—filed an amicus brief echoing Duke Energy’s concerns and urging Supreme Court intervention. Echoing Duke’s position, the amici say the Fourth Circuit’s opinion contradicts precedent against stitching legal conduct into a claim of illegal conduct, discourages competitive practices and innovation, and risks stifling investment, competition, and consumer welfare.
The amici argue that the monopoly broth theory has already been invoked in other regulated sectors, including pharmaceuticals, retail advertising, and telecommunications. They caution that unless corrected, the decision could embolden plaintiffs to bypass established legal standards, creating unpredictable liability risks across the economy.
Respondents’ Brief
In response, respondents NTE Carolinas II, LLC and affiliates urge the Supreme Court to deny review, arguing that the Fourth Circuit’s decision is consistent with established antitrust precedent. Key counterpoints include:
Alignment with Precedent: Respondents assert that the Fourth Circuit did not rely solely on the monopoly broth theory. Instead, the court found evidence of multiple independently unlawful acts by Duke Energy, such as exclusionary pricing, unlawful refusal to deal, and sham litigation—any of which could support a monopolization claim under Section 2 of the Sherman Act.
Holistic Assessment Permitted: The respondents emphasize that Supreme Court precedent—including Aspen Skiing Co. v. Aspen Highlands Skiing Corp. and Verizon Communications Inc. v. Trinko—supports evaluating anticompetitive conduct holistically, without restricting antitrust liability to discrete, independently unlawful acts. They note that the Fourth Circuit’s approach is consistent with the case law of other appellate courts.
Fact-Bound and Specific: Respondents contend that the decision is narrowly tailored to Duke Energy’s conduct as a government-backed monopolist controlling over 90% of the Carolinas wholesale power market. They argue that the ruling does not create broad uncertainty, but instead addresses a fact-specific misuse of monopoly power resulting in concrete anticompetitive harm (reduced consumer choice, higher prices, and market foreclosure).
No Compelling Reason for Review: Finally, the respondents argue that there is no genuine legal conflict or circuit split as claimed by Duke Energy. They maintain that the case remains at a preliminary stage, with further trial proceedings possible, making Supreme Court review premature.
In summary, the respondents urge the Court to deny certiorari, arguing that the Fourth Circuit’s ruling faithfully applies established precedent, is appropriately limited to the facts of the case, and preserves the flexibility needed to address complex exclusionary schemes in antitrust law.
Conclusion
The Supreme Court’s decision on whether to review Duke Energy Carolinas, LLC v. NTE Carolinas II, LLC could have significant implications for antitrust law and enforcement. At stake is whether lawful business practices can be aggregated into antitrust violations under the “monopoly broth” theory, or whether clear, independent proof of unlawful conduct is required. The outcome could be significant in reshaping an important aspect of competition law.
Edited by Tom Hagy for Mogin Law LLP.
