Antitrust Law Daily Wrap Up, ANTITRUST NEWS: Supreme Court denies review in two antitrust cases, (Oct 22, 2025)

By Peter Reap, J.D., LL.M.

The High Court had been asked to resolve disputes over an alleged conspiracy based on trade association rules and Noerr-Pennington immunity.

The U.S. Supreme Court denied certiorari in two antitrust cases on October 20, 2025. The first case involves an alleged conspiracy to restrain trade in the real estate listings market, with petitioner Real Estate Exchange, Inc. (“REX”) asking the court whether a trade association can immunize one of its rules for members from being considered a conspiracy subject to Sherman Act Section 1. The second petition was brought by Chatom Primary Care, P.C. and asked the High Court to take up an issue of Noerr-Pennington immunity in a case brought over representations by a pharmaceutical manufacturer to the Food and Drug Administration (FDA) (Real Estate Exchange, Inc. v. Zillow Group, Inc., No. 25-236; Chatom Primary Care, P.C. v. Merck & Co., Inc., No. 25-45).

Real estate listings. Real Estate Exchange, Inc. (“REX”) has been denied its petition for a writ of certiorari asking the Supreme Court to review a decision by the U.S. Court of Appeals for the Ninth Circuit. Rex had brought suit under the Sherman Act suit against the Zillow Group, Inc. and the National Association of Realtors (“NAR”) over the positioning of REX’s real estate listings on Zillow’s website.

REX filed the suit in response to a practice Zillow adopted, in January 2021, of relegating REX listings on the Zillow.com website to a separate tab called “Other listings.” REX said this caused the number of its listing views to plummet. Users had to actively select the “Other listings” tab. The change likely occurred as a result of Zillow joining hundreds of multiple listing services (MLSs) as a participant broker, such that Zillow itself came to provide brokerage services in connection with the Zillow website. Roughly two-thirds of the MLSs required Zillow to comply with their other Internet data exchange (IDX) rules. These rules incorporated NAR’s non-mandatory no-commingling rule, thereby leading Zillow to implement the two-tab display that relegated REX’ listings to the “Other listings” tab.

Following a district court ruling in favor of NAR’s motion for summary judgment, the Ninth Circuit determined that REX cannot prove that Zillow and NAR committed to a common, anticompetitive scheme and that the district court had correctly granted summary judgment. The court also determined that “any conspiracy between Zillow and MLSs alone was not clearly raised before the district court and accordingly need not be considered on appeal.”

In its petition, Rex argued that the Supreme Court should hear the case because of a number of reasons. First, REX pointed to a split among the circuit courts as to whether an association of competitors conspires when it publishes an optional rule for its members. REX argued that given that the First, Third, and Fifth Circuits have conflicted with the view of the Ninth and Tenth Circuits on whether an association’s optional rule is concerted action subject to Sherman Act Section 1, Supreme Court review on this issue is necessary.

REX also argued that the case should be reviewed because the Ninth Circuit erred in its decision. REX asserted that “two errors arose from the Ninth Circuit’s false premise that an association of competitors does not conspire when it publishes an optional rule for its members: (A) the error that NAR’s publication of the rule was not a conspiracy in itself, and (B) the error that Zillow’s change in conduct to adhere to the rule was not a conspiracy.” Argued REX, “the Ninth Circuit’s holding is troublingly inconsistent with the positions of this Court, the First, Third, and Fifth Circuits, and the Antitrust Division.” Treating “optional” rules as immune from antitrust scrutiny “rest[s] on formalistic distinctions rather than actual market realities,” which is “generally disfavored in antitrust law.”

The petition also argued the case should be heard given the “extraordinary” implications for homeowners as well as the broader economy. The petition highlighted that in the U.S., real estate commissions are suspiciously inflated and granting immunity for "optional" rules risks widespread anticompetitive conduct across industries with business associations.

Noerr-Pennington immunity. With its now denied petition for certiorari, Chatom Primary Care sought to challenge a Third Circuit opinion that granted Merck & Co. immunity from antitrust claims related to submissions made to the FDA regarding Merck's mumps vaccine. The petition asked the Court to address a split amongst the circuits as to the question presented: “Is intentional deception of the government in an adjudicative proceeding completely immunized from antitrust liability so long as the deception succeeds?”

The case began when a primary care group and two physicians filed a consolidated amended class action complaint on behalf of direct purchasers of drug manufacturer Merck & Co., Inc.’s mumps vaccines, MMR-II and ProQuad. Merck allegedly misrepresented the efficacy of those mumps vaccines to the federal government in order to secure a monopoly in that market. In their telling, the false and misleading information Merck submitted about its vaccine to the FDA precluded rival drugmaker GlaxoSmithKline (previously SmithKlineBeecham) from obtaining a FDA license to sell either of its own mumps-containing vaccines in the U.S., causing direct purchasers such as themselves to be overcharged. The complaint alleged that Merck unlawfully extended its apparent monopoly by making false drug-label claims with the goal of thwarting competition, in violation of § 2 of the Sherman Act.

The Third Circuit determined that Merck's actions were protected by Noerr-Pennington immunity, which shields genuine petitioning of government from antitrust lawsuits, even if the petitioning had a commercial impact and involved unethical conduct.

The petitioners first argued that the Supreme Court should grant certiorari because of a circuit split as to the question presented: while the Third Circuit has flat out “reject[ed] a standalone exception to Noerr-Pennington immunity for petitions containing fraudulent misrepresentations,” the petition asserts that “ten other circuits, though, have refused to provide blanket immunity for intentional misrepresentations, and in so doing have expressly acknowledged the split with the Third Circuit.” Further, the petition averred that these “circuits do not grant Noerr-Pennington immunity where the anticompetitive conduct” consists of “knowing misrepresentations” made “in the administrative and adjudicatory contexts.”

The petitioners also presented argued that the Third Circuit fundamentally misapplied Noerr-Pennington. They asserted that both caselaw and constitutional avoidance principles support the position that “there is no immunity for a company that successfully defrauds the government in an adjudicatory proceeding for the purpose of suppressing competition.”

The American Antitrust Institute (AAI) had submitted an amicus brief in support of Chatom’s petition. The AAI argued knowing misrepresentations serve no useful purpose and hence the High Court must clarify whether Noerr-Pennington immunizes fraudulent misrepresentations. AAI said the Third Circuit’s present interpretation of the Noerr-Pennington doctrine expands on disfavored immunity by shielding knowing misrepresentations to adjudicators from antitrust scrutiny and this interpretation has been rejected by other circuits.

Attorneys: Kellie Lerner Shinder Cantor (Shinder Cantor Lerner LLP) for Chatom Primary Care, PC. Charles Randall Flores (Flores Law PLLC) for Real Estate Exchange, Inc.

Companies: Chatom Primary Care, PC; Merck & Co., Inc.; Real Estate Exchange, Inc.; Zillow Group, Inc.

News: Antitrust GCNNews