A Changing Landscape of State Antitrust Enforcement

While the current federal administration retained many of its predecessor’s written antitrust policies – including the 2023 Federal Merger Guidelines – its implementation thereof has deviated. States have begun to fill the gap between the current and former administration. Indeed, states have begun to empower their own enforcers to reshape markets. Savvy businesses can no longer expect states to mirror federal law or federal enforcement priorities; rather, they must stay abreast of the latest developments or risk antitrust jeopardy.

Historically

Historically, “states were the regulators of first instance of microeconomic activities”. Wayne D. Collins, Trusts and the Origins of Antitrust Legislation, 81 Fordham L. Rev. 2279, 2335 (2013). “Consistent with the prevailing notions of federalism, the responsibility for . . . preserving competition originally fell to the individual states”. Id. Indeed, prior to the Sherman Act’s 1890 passage, 13 states had enacted their own antitrust law: Iowa, Kansas, Maine, North Carolina, Nebraska, Texas, Tennessee, Missouri, Michigan, Mississippi, North Dakota, South Dakota, and Kentucky. Id. That is, states observed a federal regulatory gap and attempted to fill it.

Over time, federal enforcement assumed greater importance. After all, “[t]he Commerce Clause empowers Congress ‘[t]o regulate Commerce . . . among the several States[.]’” Dep’t of Revenue of Ky. v Davis, 553 U.S. 328, 337 (2008) (quoting U.S. Const. art. I, § 8, cl. 3) (ellipses original). “Implicit in this grant is that the [s]tates lack the ability to regulate interstate commerce; this implied doctrine is known as the ‘dormant’ Commerce Clause”. Connecticut v Sandoz, Inc., 820 F. Supp. 3d 125, 164 (D. Conn. 2026) (citing Davis, 553 U.S. at 337). Consequently, states lack the authority to police certain forms of interstate, potentially anticompetitive conduct. For example:

• Cangrejeros De Santurce Baseball Club, LLC v Liga De Beisbol Profesional De Puerto Rico, 146 F.4th 1, 23 (1st Cir. 2025), cert. denied sub nom. Cangrejeros de Santurce Baseball Club, LLC v Liga de Beisbol Pro. de Puerto Rico, Inc., 146 S. Ct. 1780 (2026) (explaining that the Commerce Clause generally precludes application of state antitrust laws to interstate sports leagues but not to purely intrastate sports leagues); and
• Partee v San Diego Chargers Football Co., 668 P.2d 674, 679 (Cal. 1983) (finding the Commerce Clause precludes application of state antitrust law to a National Football League franchise).

In an increasingly integrated economy, therefore, one may expect that states would – even if only by necessity – cede antitrust authority to federal regulators. See, for example, Partee, 668 P.2d at 679. States even began to tie their antitrust regimes to the federal one for that reason. For example:

• Conn. Gen. Stat. Ann. § 35-44b (requiring courts to “be guided by interpretations given by the federal courts to federal antitrust statutes”);
• Del. Code Ann. tit. 6, § 2113 (requiring the state antitrust law to “be construed in harmony with ruling judicial interpretations of comparable federal antitrust statutes”);
• 740 Ill. Comp. Stat. Ann. 10/11 (stating that “[w]hen the wording of [a state antitrust law] is identical or similar to that of a federal antitrust law, the courts of [Illinois] shall use the construction of the federal law by the federal courts as a guide”); and
• Vt. Stat. Ann. tit. 9, § 2453a (stating “the courts of this State shall be guided by the construction of federal antitrust law and the Sherman Act”).

But an increasingly integrated economy also means that any given state is increasingly likely to have a nexus to any given antitrust issue. See 58 C.J.S. Monopolies § 56 (explaining that “state antitrust laws can apply to interstate commerce provided the commerce has significant local consequences or substantially affects the people of the state and has impacts in the state, when actionable antitrust conduct occurs in the state”).

States have adopted the latter interpretation and, in some respects, returned to their historical place at the vanguard of antitrust enforcement. “Congress intended the federal antitrust laws to supplement, not displace, state antitrust remedies”. California v ARC Am. Corp., 490 U.S. 93, 102 (1989) (citing 21 Cong.Rec. 2457 (1890) (remarks of Sen. Sherman)) (emphasis added). That is, states are increasingly treating their antitrust regimes as complementary to, or compensatory for, the federal one, not merely coextensive with it.

Why?

Questions have arisen regarding the recent resurgence of state antitrust enforcement. Some have speculated that the federal government’s approach has created an opportunity, not an obligation – that is, demand, not necessarily a need – for states to get involved.

Policy differences

First, state activity may be explained by policy differences. “Customarily, state regulators have piggybacked on antitrust cases brought and managed by the federal government. The fed[eral enforcers] generally have greater resources than most individual states to conduct the investigations that can lead to antitrust lawsuits”. To that end, Illinois’s top antitrust official, Elizabeth Maxeiner, posited that state enforcers will necessarily bring more cases “when there’s a . . . shift in how the federal agencies approach [their] cases”.

Process concerns

Other officials have objected to process, not merely policy. Maxeiner contended that, in such situations, “states don’t really have a choice but to [bring cases] independently”. Id. Colorado’s Attorney General Philip J. Weiser took a similar stance, claiming that states are taking action due to a lack of collaboration with the federal government. “[A]s the federal agencies become less transparent...”, reasoned Maxeiner, “you’re just going to see more state enforcement”. To be clear, as of this writing (September 2026), no court has found the Trump administration acted unlawfully with regard to any major antitrust case, nor has any court blocked the proposed settlements discussed in this article. Ultimately, however, whether the state officials’ allegations are actually true is immaterial to this analysis; they do not need to be true to have an effect. People can still act upon – and lawsuits can be brought because of – mistaken, though well-intentioned, beliefs.

Meeting demand

Another view is that states are simply responding to constituent demand. Broadly, antitrust enforcement is popular. As living costs rise, legislators are incentivised to find solutions. Antitrust offers a potential – and popular – set of tools, and state attorneys general can build support by deploying it. Lighter federal enforcement allows state officials to fill a perceived gap – regardless of need or actual effect of intervention – in pursuit of electoral gain. In this light, the uptick of state antitrust activity is not necessarily a response to a genuine economic need but rather to political incentives (demand). To illustrate: while Weiser may indeed believe that certain federal decisions “call out for scrutiny”, he is also the Democratic candidate to be Colorado’s next governor. Similarly, Texas Attorney General Ken Paxton, who is running for the US Senate, recently threatened to file antitrust claims against the Big 12 Conference if it sanctioned Texas Tech University for rostering a certain player on its football team that the NCAA had deemed ineligible. Oklahoma’s own Attorney General responded to Paxton’s threats with his own letter, asserting that the Big 12 Conference would not violate antitrust laws – and noting that his office “has a direct interest in the integrity of [Big 12] competition” because Oklahoma State University is a member of the Big 12 Conference.

Regardless of the source of the concern – policy or process, and often both – presidential involvement is likely to increase, setting the stage for further disagreements with state officials. Indeed, the US Supreme Court recently held that “[t]he FTC unquestionably exercises executive power, and must therefore be controlled by the Chief Executive, in whom such power is vested. It follows, then, that [FTC commissioners] serve [...] as the President’s subordinate at the FTC – and that the President [is] entitled to cut [t]he[i]r tenure[s] short”. Trump v Slaughter, No. 25-332, 2026 WL 1855612, at *18 (U.S. June 29, 2026). That is, the President – regardless of party – will now have increased authority over the agency that “enforces and administers some 80 statutes, which cover almost every facet of our Nation’s economy”. Id. at *17. Because “the FTC files civil suits on behalf of the United States in federal court”, and “may select its remedies freely – from injunctions . . . to civil penalties, . . . to any relief necessary to redress injury to consumers, including the refund of money or return of property”, id. (internal citations omitted), some officials, like Maxeiner, have raised concerns that increased presidential control will “likely push the agency towards becoming more political in its decision-making” over time.

How?

States filing or joining lawsuits

To some, the proposed Nexstar-Tegna merger presents a strong example of state attorneys general responding to policy concerns. While federal authorities approved of the deal, which would have created the country’s largest operator of local television stations, a bipartisan coalition of states sued to block the merger. The state officials argued that the deal would “degrade the quality and quantity of local news programming”. The state officials won a preliminary injunction to pause further integration pending adjudication on the merits. In re Nexstar-Tegna Merger Litig., No. 2:26-CV-00976-TLN-CKD, 2026 WL 1049295, at *28-31 (E.D. Cal. Apr. 17, 2026).

Some have identified the HPE-Juniper merger as an example of states responding to process concerns. As initially proposed, the HPE-Juniper merger would have roughly doubled the size of HPE’s networking business, and “bridg[ed] the global strength of HPE in enterprise security-first networking and SASE security with Juniper’s position in data center, service provider, and AI-native solutions”. The federal government initially opposed the combination but eventually reversed course in what it described as a negotiated, “novel” settlement. State attorneys general moved to intervene, accusing “the government and HPE [of withholding] information from their statutorily required disclosures about the alternative remedies considered” and about lobbyist involvement. Their efforts resulted in what some have deemed “the most significant courtroom vetting of an antitrust settlement between the government and a technology company in 30 years”.

Kwame Raoul (the Illinois Attorney General) has argued that a recent lawsuit involving Live Nation also shows states acting due to process concerns. The Live Nation suit, brought by the prior administration and a bipartisan coalition of 29 states, alleged that Live Nation leveraged its ownership of concert venues, ticket-selling platform, and concert-promotion arm “to lock in . . . artists” and engage in a “deliberate and defensive series of actions and decisions designed to lock up venues, lock out competitors, and hold the industry hostage from innovation and evolution”. The plaintiffs sought monetary penalties and asked the court to force Live Nation to spin off Ticketmaster. United States, et al. v Live Nation Entertainment, Inc. and Ticketmaster Entertainment, LLC. No. 1:24-cv-03973 (S.D.N.Y. filed May 23, 2024 at ¶ 371. Years later, however, “a few days after the trial began this spring, the Justice Department reached a settlement with Live Nation”. Neither party informed the judge overseeing the case at a meeting in his chambers the following morning, a decision he criticised as “absolutely unacceptable”. Id.

A bipartisan coalition of 34 states pressed forward, however, and, in April 2026, the jury ultimately found for the plaintiffs on every state law claim.

States’ legislative responses

Outside of the courtroom, state legislatures are making similar moves. Indiana empowered its attorney general to investigate the market concentration of health care entities. Colorado repealed its previous statutory directive that “in construing [its main antitrust law], the courts shall use as a guide interpretations given by federal courts to comparable federal antitrust laws”, and adopted the Uniform Antitrust Pre-Merger Notification Act. Colo. Rev. Stat. § 6-4-119 (1992). West Virginia is considering adopting similar notice requirements. California recently lowered its antitrust pleading threshold and regulated algorithmic pricing. Cal. Bus. & Prof. Code § 16756.1. New York enacted its own algorithmic pricing regulations. N.Y. Gen. Bus. Law § 349-a. Other states, like Ohio, may enact similar measures.

The Illinois legislature has been particularly active. It enacted a “Baby HSR” law, 740 Ill. Comp. Stat. Ann. 10/7.2a, and is poised to dramatically broaden the state’s healthcare transaction notice requirements by requiring notice to the Illinois Attorney General for any merger, acquisition, or contractual affiliation “involving” two or more previously unaffiliated healthcare facilities or provider organisations; the prior version of the law required notice when the transactions were “between” such entities. It is also considering a ban on non-compete clauses, and recently passed a bill outlawing price co-ordination or contracting with a service involving price co-ordination for residential units in the state.

States have done this before. Many states have passed “Illinois Brick repealer” laws, for example. These allow indirect purchasers to sue and recover for antitrust violations, which federal law generally bars – eg, 740 Ill. Comp. Stat. Ann. 10/7. That is, the recent uptick in state activity marks a return to their antitrust roots. “[A] single courageous state may, if its citizens choose, serve as a laboratory; and try novel social and economic experiments without risk to the rest of the country”. New State Ice Co. v Liebmann, 285 U.S. 262, 311 (1932). A lighter-touch federal government has created opportunities for them to do so, to conduct experiments, such as regulating artificial intelligence, that the federal government has been unwilling – or unable – to attempt. But some experiments are volatile, and others yield disappointing results. Companies and lawyers would do well to watch them closely.

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Author’s note: Thank you to William Weber for his assistance in preparing this article.