CoStar Asks Supreme Court to Resolve Antitrust Battle With CREXi

CoStar Group on December 10 asked the U.S. Supreme Court to review a legal fight with rival Commercial Real Estate Exchange Inc, bringing to the high court a dispute about whether dominant digital platforms can lawfully deny competitors access to crucial databases and tools. The move follows a June decision by the Ninth U.S. Circuit Court of Appeals that reinstated CREXi’s antitrust claims after a lower court dismissed them.

CREXi alleges that CoStar unlawfully restricted commercial real estate brokers to CoStar owned platforms and denied competitors access to critical digital tools, conduct CREXi says harmed competition and raised costs for brokers and brokerage firms. CoStar denies any wrongdoing, arguing that it has no obligation to grant rivals access to its proprietary websites and databases and that the appeals court’s ruling threatens to chill innovation and spur costly litigation across many industries.

The dispute traces back to a 2020 copyright lawsuit in which CoStar accused CREXi of copying tens of thousands of real estate photographs. That earlier litigation established a contentious legal backdrop and now the antitrust claims will test broader questions about refusal to deal doctrines in the digital economy. In its petition, CoStar warned that the Ninth Circuit ruling raises sweeping issues about a company’s right to withhold commercial access from rivals and could create new obligations for owners of proprietary information.

Legal scholars and market participants say the case raises two intertwined issues. First, whether antitrust law requires companies with substantial market power to share data or functionality with competitors, particularly in sectors where proprietary information is central to product value. Second, how courts should balance the harms of exclusionary practices against the incentives for firms to invest in platforms and data systems. The Supreme Court has been cautious in expanding duties to deal under antitrust law in prior decisions, and a decision to take this case would signal the court’s willingness to clarify how those principles apply to modern digital marketplaces.

The commercial real estate sector has seen accelerating reliance on digital platforms for listings, transaction management and analytics, turning access to data into a competitive asset. For brokers and smaller marketplaces, limits on interoperability or denied access can translate into higher search costs and reduced market liquidity. For investors and platform operators, an adverse ruling could increase compliance costs and heighten litigation risk, particularly for start ups seeking to scale in a market dominated by a few large incumbents.

If the Supreme Court accepts the petition, the case could yield a precedent that reshapes antitrust enforcement in data intensive industries beyond real estate, including online marketplaces and business to business platforms. If the court declines, the Ninth Circuit’s framework will stand and may prompt a wave of similar claims challenging unilateral refusals to deal. Either pathway carries implications for competition policy, platform strategy and long term innovation dynamics in markets where proprietary data powers commercial advantage.