Copperweld Corporation acquired Regal Tube Company, an established manufacturer of steel tubing. Independence Tube Corporation was formed by individuals, including a former Regal manager, to enter the same market and sought to purchase equipment and financing necessary to commence operations. Copperweld and its wholly owned subsidiary Regal opposed this entry and, through counsel, sent letters to Independence Tube's prospective equipment supplier and others, asserting legal claims based on alleged misuse of confidential information and related state-law theories. Independence Tube alleged that these coordinated efforts by Copperweld and Regal delayed its market entry and harmed its business by coercing third parties to withhold essential inputs. Independence brought federal antitrust claims, including a §1 Sherman Act conspiracy claim premised on the coordinated conduct between Copperweld and Regal. A jury found for Independence on the §1 theory, and the court of appeals affirmed. The Supreme Court granted certiorari to decide whether a parent and its wholly owned subsidiary can, as a matter of law, conspire with each other under §1.
Can a parent corporation and its wholly owned subsidiary conspire with each other within the meaning of §1 of the Sherman Act?
Concerted action under §1 of the Sherman Act requires an agreement among separate economic actors pursuing separate interests such that the agreement deprives the marketplace of independent centers of decisionmaking. A parent corporation and its wholly owned subsidiary have a complete unity of interest and function as a single economic enterprise; their coordinated conduct is deemed unilateral action and is not actionable as a §1 conspiracy. Such conduct remains subject to antitrust scrutiny, when appropriate, under other provisions such as §2 of the Sherman Act and §7 of the Clayton Act.
No. A parent corporation and its wholly owned subsidiary are legally incapable of conspiring with each other under §1 of the Sherman Act because they constitute a single economic entity.
The Court emphasized that §1 addresses agreements among separate economic actors who otherwise would compete and whose combination deprives the market of independent decisionmakers. A parent and its wholly owned subsidiary do not have divergent economic interests; their profits and losses are shared, and the parent exercises control over the subsidiary's decisionmaking. Treating their coordination as a conspiracy would elevate corporate form over economic substance and risk condemning ordinary internal firm planning as per se unlawful. The Court criticized the intra-enterprise conspiracy doctrine for producing anomalies—exposing internal coordination to treble-damages liability simply because of corporate structuring—while failing to advance §1's procompetitive aims. By focusing on economic reality and unity of interest, the Court held that parent–subsidiary coordination is unilateral conduct for §1 purposes. The decision does not immunize anticompetitive behavior; integrated firms remain subject to §2 liability for monopolization or attempted monopolization and to merger control under §7 of the Clayton Act. To the extent earlier cases suggested otherwise, they were rejected in favor of this single-entity approach. The dissent argued that separate incorporation can produce independent decision centers and that a bright-line rule risks underdeterrence, but the majority concluded that coherence and economic reality favored the single-entity rule for wholly owned subsidiaries.
Copperweld is a cornerstone of modern antitrust doctrine distinguishing unilateral conduct from concerted action. It eliminates §1 conspiracy exposure for coordination between a parent and its wholly owned subsidiary, simplifying corporate planning and litigation risk assessment. At the same time, it preserves robust antitrust oversight through §2 and merger enforcement. For law students, the case clarifies how to analyze alleged conspiracies within corporate families, how to frame claims post-Copperweld, and how to apply the single-entity concept in later cases, including American Needle's more nuanced treatment of joint ventures and partially owned affiliates. It is frequently examined to test understanding of the difference between §1 concerted action and §2 unilateral conduct, and how economic substance can prevail over formal corporate structure.
Copperweld draws a clear line in antitrust law: coordination within a single economic enterprise—at least in the parent–wholly owned subsidiary context—is unilateral action, not the concerted action that §1 of the Sherman Act targets. By privileging economic substance over corporate form, the Court aimed to prevent ordinary internal planning from being miscast as a cartel-like agreement.