A coalition of technology industry groups and former antitrust officials is urging the U.S. Supreme Court to review a Ninth Circuit decision that reinstated antitrust counterclaims against CoStar Group Inc., a leading commercial real estate information provider. The case centers on allegations by Commercial Real Estate Exchange Inc. (CREXi) that CoStar engaged in anticompetitive practices to maintain its market dominance.
In September 2020, CoStar initiated legal action against CREXi, accusing the competitor of unauthorized use of its copyrighted content. In response, CREXi filed counterclaims alleging that CoStar employed exclusive agreements and technological barriers to stifle competition. The district court dismissed these counterclaims, but the Ninth Circuit reversed this decision in June 2025, allowing CREXi’s antitrust allegations to proceed. ([law.justia.com](https://law.justia.com/cases/federal/appellate-courts/ca9/23-55662/23-55662-2025-06-23.html?utm_source=openai))
CoStar has since petitioned the Supreme Court to review the Ninth Circuit’s ruling, contending that the appellate court’s acceptance of a “de facto” exclusive dealing theory deviates from established antitrust principles. The company argues that this interpretation could lead to an increase in unfounded antitrust lawsuits. ([law360.com](https://www.law360.com/media/articles/2419962/costar-urges-justices-to-review-revived-antitrust-claims?utm_source=openai))
Supporting CoStar’s petition, the Chamber of Progress—a technology industry coalition—asserts that the Ninth Circuit’s decision undermines established protections against refusal-to-deal claims, potentially exposing companies to increased legal uncertainty. ([mlex.com](https://www.mlex.com/mlex/articles/2378651/costar-crexi-appeal-ruling-undermines-us-refusal-to-deal-protections-tech-group-says?utm_source=openai))
Additionally, a group of former antitrust officials and scholars has submitted an amicus brief expressing concern that the Ninth Circuit’s ruling could disrupt foundational antitrust principles and encourage baseless litigation. ([laweconcenter.org](https://laweconcenter.org/resources/brief-of-former-antitrust-officials-and-scholars-to-the-9th-circuit-in-costar-v-crexi/?utm_source=openai))
The Supreme Court’s decision on whether to grant certiorari in this case is anticipated to have significant implications for antitrust enforcement and the interpretation of exclusive dealing arrangements in the commercial real estate sector and beyond.