| Randy Stutz, Kathleen W. Bradish, David O. Fisher
Section 1 of the Sherman Act, Price Fixing, Collusion
On December 19, 2025, the American Antitrust Institute (AAI) filed an amicus brief in In re Rail Freight Fuel Surcharge Antitrust Litigation (No. I), MDL No. 1869, asking the D.C. Circuit to faithfully apply the Supreme Court’s framework for assessing whether a cartel agreement can be inferred from circumstantial evidence.
Because most price-fixing is done in secret, plaintiffs in Section 1 cases under the Sherman Act rarely can adduce direct evidence of a cartel agreement. When they must rely instead on an inference of agreement from circumstantial evidence, the Supreme Court has created a two-part framework for assessing whether such an inference is permissible. The plaintiffs must plead and prove (1) parallel conduct and (2) so-called “plus factors,” which can be any additional evidence that is suggestive of a meeting of the minds in an unlawful arrangement.
In Rail Freight, the plaintiffs are railroad shippers who allege that the nation’s four largest railroad companies—BNSF, CSX, Norfolk Southern, and Union Pacific, which together control about 90% of the U.S. freight railroad market—conspired to raise prices for rail freight shipments by imposing aggressive universal fuel surcharges on customers. The district court granted summary judgment for the defendants, holding that the plaintiffs failed to make a threshold showing that the defendants even acted in a parallel fashion, let alone the requisite showing of both parallel conduct and plus factors. The court reasoned that in an oligopoly market, where “conscious parallelism” sometimes can explain parallel price increases that are also consistent with an unlawful agreement, the plaintiffs must plead and prove “unusual parallel conduct,” meaning conduct that could not be explained by the phenomenon of oligopolistic interdependence.
The court believed that, in this sense, plus-factor analysis can “bleed into” the parallel conduct inquiry. Here, the court held, the plaintiffs failed to offer evidence that accounted for differences in the defendants’ specific fuel surcharge formulas and the timing in which they adopted them. Accordingly, the plaintiffs did not satisfy the threshold parallel conduct requirement.
In its brief, AAI explains that the district court’s approach alters and distorts the Supreme Court’s framework by conflating its two parts. Instead of requiring parallel conduct and plus factors, the district court required parallel conduct that is “unusual” in its parallelism. Such an approach smuggles a narrow subset of timing and simultaneity plus factors into the threshold requirement, raising the plaintiffs’ burden, and invites courts to ignore all other plus factors that fall outside the subset. The effect is to convert certain plus factors into elements, which prevents plus-factor analysis from serving as the flexible, holistic, and context-dependent indicator of collusion that the Supreme Court intended it to be.
AAI also explains that the district court’s approach is flawed economically and as a matter of competition policy because it wrongly assumes that supracompetitive prices in an oligopoly can always be explained by oligopolistic interdependence. Such an assumption tips the scale against a finding of collusion in the very markets in which collusion is most likely to occur and in which the cost of overdeterrence is comparatively low.
The brief was written by AAI President Randy Stutz, AAI Vice President and Director of Legal Advocacy Kathleen Bradish, and AAI Senior Counsel David O. Fisher.
Read the full brief: AAI Amicus Brief (In re Rail Freight Fuel Surcharge Antitrust Litig.)
