State attorneys general are playing an increasingly prominent role in shaping the antitrust enforcement landscape in the United States. With a combination of expanded authority, increased funding, strategic collaboration, and a growing desire to address state-specific concerns, state attorneys general have become key players in investigating and litigating competition issues across areas such as ESG, healthcare, pharmaceuticals, technology, merger enforcement, and algorithmic pricing.
Once viewed as a federal domain, antitrust enforcement has expanded as state attorneys general (AGs) draw on powers derived from state constitutions and both federal and state antitrust statutes to investigate anticompetitive conduct, bring civil or criminal actions, challenge mergers, and represent consumers and their states in enforcement efforts. These powers vary across states, but in general, AGs can seek injunctive relief, recover damages, and pursue cases alleging harm to a state’s general economy or proprietary interests.
Several factors are driving this state action, including a rise in consumer awareness and complaint activity, particularly around pricing, labor market impacts, and healthcare access. Many state AG offices are reporting increased constituent outreach concerning perceived anticompetitive behavior. This has contributed to more aggressive investigative postures and, in some cases, pressure on AGs to act where federal enforcement has been viewed as insufficient or too slow.
State AGs are also building out their internal capacity, adding experienced personnel, including former US Department of Justice (DOJ) Antitrust Division and Federal Trade Commission (FTC) lawyers and economists. There is also a growing trend toward the use of outside counsel, often on a contingency fee basis, to pursue investigations and litigation to take on larger-scale matters.
Interstate coordination continues to ramp up, often through the National Association of Attorneys General (NAAG) and its bipartisan Antitrust Committee, which supports the work of NAAG’s Multistate Antitrust Task Force and its 11 specialized committees and working groups, focusing on areas such as agriculture, healthcare providers, pharmaceuticals, energy, and criminal enforcement. This infrastructure enables both knowledge sharing and tactical coordination, particularly when resource-constrained states team up to pursue complex, multistate investigations. However, there are many matters that are now handled exclusively outside the NAAG Task Force and its structure.
An added tool for state enforcement was the enactment in 2023 of the State Antitrust Enforcement Venue Act that empowers state AGs to pursue antitrust cases brought under federal law in their chosen venues without consolidation into federal multidistrict litigation proceedings. This increased autonomy has allowed for more agile and localized enforcement, especially in complex or sensitive cases.
Environmental, social, and governance (ESG) issues have emerged as an example of the sharp partisan divide in state-level antitrust enforcement, including whether collaborative sustainability initiatives among companies may constitute unlawful conspiracies, for example.
In November 2024, several states filed suit against major asset managers, alleging coordinated efforts to suppress coal production. Defendants sought dismissal, arguing the plaintiffs failed to plausibly allege an agreement or anticompetitive information-sharing scheme. In January 2025, a coalition of Republican AGs sent warning letters to major financial institutions, alleging that ESG commitments, including diversity and climate goals, may violate fiduciary duties and antitrust laws.
Similar challenges have been raised regarding participation in climate-related alliances like Climate Action 100+, the Net-Zero Asset Managers initiative, and the Net-Zero Banking Alliance. For example, Republican AGs have issued civil investigative demands to probe whether a Net-Zero Banking Alliance affiliation constitutes deceptive practices or consumer protection violations. Meanwhile, Democratic AGs argue that managing climate risk may be part of a fiduciary duty, not a violation of it.
Pharmaceutical pricing remains a core area of antitrust enforcement. For over a decade, state AGs have pursued claims of price fixing and market allocation involving generic drugs, culminating in three major lawsuits involving over 100 drugs. Settlements have surpassed $49 million, with additional business reforms secured.
Pharmacy Benefit Managers (PBMs) are also under scrutiny. In the ongoing insulin multidistrict litigation, AGs from red and blue states alike allege that drug manufacturers and PBMs have acted to inflate insulin prices through complex rebate programs. While the case remains pending, several states have reached settlements, and Congress is considering bipartisan legislation to restructure the PBM industry. The FTC has also taken administrative actions in this area, reflecting both state and federal scrutiny.
Some legislators in states like New York and California are contemplating major reforms to expand the scope and strength of their antitrust statutes. For example, New York’s proposed Twenty-First Century Antitrust Act would introduce an “abuse of dominance” standard and establish presumptions of market power based on relatively low share thresholds of 40% for sellers and 30% for buyers. This draft bill also proposes comprehensive premerger notification and enhanced rulemaking authority for the AG.
California, meanwhile, has tasked its Law Revision Commission with proposing updates to the state’s Cartwright Act. Recommendations under consideration include addressing single-firm conduct and introducing new merger approval and prenotification laws. Though still in the deliberative phase, California’s process reflects a growing national trend of considering state-level modernization of antitrust tools.
In addition to the legislative developments mentioned above, several state legislatures have enacted so-called “mini HSR” laws, bringing heightened scrutiny to healthcare mergers in particular. Modeled on the Hart-Scott-Rodino (HSR) Act, which provides for premerger notification to the federal antitrust agencies for many mergers and acquisitions, these analogous state laws often require preclosing notifications of certain transactions to state authorities, even when no federal filing is triggered. To date, most of these state laws focus on the healthcare sector.
State healthcare merger notification laws are already on the books in California, Colorado, Connecticut, Illinois, Indiana, Massachusetts, Minnesota, Nevada, New Mexico, New York, Oregon, and Vermont. These statutes vary by state as to their specific requirements, such as which parties must file, what information is required, the length of notice, and potential penalties for non-compliance.
State AGs also continue to pursue monopolization claims against major technology platforms, sometimes in coordination with federal authorities and sometimes independently on multi-state bases. In one pending case, a group of states joined the DOJ in alleging monopolization in digital advertising technologies. In another case filed in 2024, a broad coalition of states alleged anticompetitive practices in the smartphone market.
Not all state enforcement efforts in this area have been successful. A case brought by 48 states against a major social media platform was dismissed for procedural reasons, despite a parallel FTC case moving forward. Still, these efforts underscore states’ willingness to challenge large technology companies under the antitrust laws.
State AGs are increasingly focused on algorithmic pricing tools, particularly when used in the housing and rental markets, expressing concerns that certain algorithmic price recommendation services may violate antitrust law. Emblematic of this trend are the RealPage litigations, in which the DOJ and multiple states have alleged that the use of rent recommendation software relying on nonpublic data from multiple property management companies violates the Sherman Act or similar state laws.
While a federal civil case brought by the DOJ Antitrust Division and several states proceeds, several other state AGs, including those in Arizona, Maryland, Washington State, and DC, have filed their own lawsuits under state antitrust laws. Additionally, jurisdictions such as San Francisco, Philadelphia, Minneapolis, and Berkeley have passed ordinances restricting the use of such tools. Other similar legislative proposals are under consideration in at least 11 states.
State AGs are asserting their independence and deepening their capacity in antitrust enforcement. Enhanced coordination among themselves and through NAAG, an influx of former federal prosecutors and economists into state offices, and growing political and consumer pressure have created momentum for states to lead significant antitrust enforcement efforts.
Businesses should expect more multistate enforcement, increased use of state-specific statutes, and expanded interest in topical areas like ESG and algorithmic pricing. With the potential for both state and federal action on priorities that may or may not align, companies must navigate an evolving enforcement map, in which the path may run through Washington, DC, state capitals, or both.
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