The U.S. Supreme Court has declined to review Real Estate Exchange Inc. v. Zillow Group, Inc. and National Association of Realtors, leaving intact a Ninth Circuit decision that dismissed claims of anticompetitive conduct in the online real estate marketplace. The denial marks the end of a closely watched case that challenged how digital platforms and industry rules can shape and possibly suppress competition.
In our view, the Court missed an opportunity to begin to deal with a significant issue of competitive abuses by platform operators that disadvantage consumers. If that goal is too ambitious then the Court missed an opportunity to begin to find competitive balance between platform operators, other stakeholders and consumers.
Suppressing Competition Through Design and Policy
REX, a now-defunct real estate brokerage, alleged that Zillow and NAR conspired to marginalize non-MLS listings through a website design that segregated them from MLS listings. The design change was prompted by NAR’s “no-commingling” rule, which required MLS listings to be displayed separately from other sources.
REX argued that this separation misled consumers and effectively buried its listings, harming its ability to compete. The company claimed this amounted to a concerted action under Section 1 of the Sherman Act, designed to protect entrenched players and exclude disruptive competitors.
No Agreement, No Violation
The Ninth Circuit affirmed summary judgment in favor of Zillow and NAR, finding no evidence of a coordinated agreement to restrain trade. Zillow’s decision to comply with the no-commingling rule was a” unilateral business choice,” the court determined.
Why the Supreme Court’s Denial Matters
It would have been useful to hear from the Supreme Court on how platform design and industry rules interact with antitrust law. In the digital marketplace a platform’s visibility can determine a business’s success or failure.
The case raised valid questions. Is following an industry rule enough to shield a platform from antitrust liability? Can design choices that disadvantage competitors be considered exclusionary conduct? How should courts evaluate the competitive impact of digital gatekeeping?
Markets could use clearer standards governing platform neutrality and the competitive consequences of design decisions. The case shows how even eliminated industry rules can create lasting barriers to competition.
As courts remain highly cautious about applying antitrust liability to platform conduct and ever stricter about what constitutes evidence of agreement or collusion, and as platforms increasingly influence consumer access and business visibility, future litigation and enforcement will likely take place on the blurry space between design and exclusion.
To this point, in our opinion, courts have generally been overly deferential to platform operators while significantly discounting user experience and impacts, and failing to adjust their analysis of agreement to the new techno-environment. This enhances Big Tech’s market power and leads to anti-competitive behaviors to the detriment of consumers.
Resources
Ninth Circuit Docket No.: 23-55662
Read the full opinion (PDF)
Supreme Court Docket No.: 25-326
View the certiorari petition (PDF)
Academic Perspectives from Academic Journals
Legal scholars have been examining this issue during the last few years. Below are some perspectives on how platform conduct intersects with antitrust law—a debate brought into focus by the Zillow litigation. These articles and commentary offer insights into the challenges digital platforms present for traditional antitrust frameworks, the potential impact of platform design on competition and innovation, and evolving approaches to defining markets and crafting remedies.
- Antitrust at a Crossroads: The Challenge of Digital Platforms
Authors: Giovanna Massarotto & Christopher S. Yoo
Journal: Journal of Law & Innovation (2024) — Massarotto and Yoo explore how digital platforms—particularly those that control listing formats, ranking algorithms, and data access—pose unique challenges for antitrust enforcement. They argue that traditional antitrust frameworks, which focus on price and output, are ill-equipped to address the competitive dynamics of digital ecosystems. The authors advocate for updating antitrust analysis to better assess platform behavior, while cautioning against overregulation that could stifle innovation.
- Antitrust, Innovation, and Product Design in Platform Markets: Microsoft and Intel
Authors: William H. Page & Seldon J. Childers
Journal: Antitrust Law Journal (2012) — This article reviews the Microsoft and Intel antitrust cases, focusing on how platform design can be used to suppress innovation. The authors argue that while intervention may be necessary, it must be carefully calibrated to avoid harming the very innovation antitrust law seeks to protect. The authors support antitrust enforcement when platform design is used to exclude rivals, but warn against interventions that could disrupt innovation ecosystems.
- Defining Relevant Markets in Digital Ecosystems
Author: Daniel A. Crane
Journal: Journal of Law & Innovation (2024) — Crane critiques the traditional methods of defining relevant markets in antitrust analysis, arguing they are ill-suited for digital ecosystems where multi-sided platforms and network effects complicate market boundaries. Critical of status quo, Crane calls for a rethinking of market definition tools to reflect the realities of digital competition.
- Structural Antitrust Relief Against Digital Platforms
Author: Herbert J. Hovenkamp
Journal: Journal of Law & Innovation (2024) — Hovenkamp examines remedies for antitrust violations by digital platforms, arguing that structural remedies like breakups may be counterproductive. He favors conduct remedies and regulatory oversight tailored to platform dynamics. A pragmatic reformer, Hovenkamp supports antitrust enforcement but urges caution with structural remedies, favoring more targeted approaches.
