The Antitrust Education Project and Consumer Advocates in American Real Estate (CAARE) are urging the U.S. Supreme Court to hear the Real Estate Exchange’s (REX) petition related to its antitrust suit against the National Association of Realtors (NAR) and Zillow.
Originally filed by REX in March 2021, the lawsuit alleges that NAR and Zillow broke antitrust laws when NAR promulgated its optional no-commingling rule and Zillow redesigned its website in order to follow the rule within the MLSs that adopted it.
Judge Thomas Zilly, who oversaw the case, dismissed REX’s antitrust claims against NAR and Zillow in a summary judgement ruling. REX appealed this ruling to the Ninth Circuit Court of Appeals, which affirmed the lower court’s ruling. In April 2025, the Ninth Circuit denied REX’s request for a rehearing, leaving REX no choice but to file with the Supreme Court, which it did in mid-September.
In their filing on Tuesday, the Antitrust Education Project and CAARE argue that REX’s petition is one the Supreme Court should hear.
The Antitrust Education Project wrote that the Court should review the lower court’s ruling, which found “that an agreement to impose a non-binding rule cannot constitute an agreement” that violates the Sherman Antitrust Act. The organization argues that the decision deepens the existing split among the Circuit Courts of Appeals and it departs from settled antitrust cases, as well as the consumer welfare standard.
The organization claims the lower courts mixed up two different issues — whether an agreement actually existed and whether it was effective. They argue that adopting or promoting an optional rule could still count as part of a conspiracy. They also say the courts overlooked the idea that if a company later agrees to or acts in line with an existing agreement, it can become part of it. This ties back to REX’s claim that Zillow joined the alleged conspiracy when it redesigned its website to follow the no-commingling rule.
“The case presents a fitting opportunity to do so not only because of the central role that the housing industry plays in the life of our nation, but also given that the decision below presents a textbook example of a court falling into error by seeking to protect competitors rather than consumers, and stifling innovation and new entry in order to shelter legacy market participants,” the brief states.
In allowing the ruling to stand, the amicus argues that it would set a dangerous precedent that “Realtors alone […] are to be excluded from the reach of the antitrust laws and protected from the sort of disruption the Internet has introduced into these other sectors or our economy.”
Many of these arguments are echoed by CAARE in its brief. CAARE’s executive director is Doug Miller, an attorney at Miller Law PLLC., who is best known as one the plaintiffs’ attorneys behind the Moehrl commission lawsuit.
The filing claims that the no-commingling rule “is not a standalone policy,” but rather “a product of the longstanding demands and practices promoted by NAR and the structure of local Multiple Listing Services,” and one of NAR’s “most effective weapons for suppressing competition.” CAARE argues that NAR and Zillow cooperate in a collusive system that has driven up real estate agent commissions, harming consumers.
“These artificially inflated fees are not the product of a healthy competitive market; they are the result of a concerted scheme to systematically suppress price competition and limit consumer choice,” the filing states.
By promulgating the no-commingling rule and then by Zillow’s adoption of it where required, CAARE claims the defendants caused the “evisceration” of REX. If the Supreme Court allows the Ninth Circuit’s ruling to stand, CAARE claims that it “creates a dangerous loophole in the Sherman Act that allows a trade organization to immunize its anti-competitive rules and policies simply by labeling them ‘optional.’”
The Supreme Court will decide whether or not it will hear REX’s petition in the coming months.
