ATLANTA— Delta Air Lines (DL) has secured a major legal victory after the U.S. Court of Appeals for the Eleventh Circuit vacated a Department of Transportation (DOT) order that sought to end its antitrust immunity with Aeromexico (AM).
The ruling keeps the carriers’ joint venture in place while requiring the department to reconsider how it justified its decision.
The dispute centers on the airlines’ long-running partnership between the United States and Mexico.
The DOT granted antitrust immunity in 2016, allowing Delta and Aeromexico to coordinate areas including schedules, pricing and capacity, while Mexico City’s Benito Juárez International Airport (MEX) remained a key part of the competitive debate.
Court Rejects DOT Analysis of Delta-Aeromexico JV
The Eleventh Circuit found that the DOT’s 2025 decision was “arbitrary and capricious,” concluding that the agency had not adequately explained its departure from earlier approaches to evaluating airline joint ventures.
Rather than examining competition across the broader U.S.-Mexico market, the department placed heavy emphasis on conditions at MEX.
That change became central to the court’s decision. The judges said the DOT needed to explain why it had moved away from considering the overall market, particularly when earlier reviews of international airline partnerships had used a wider market analysis.
The court also questioned the department’s treatment of airport access.
Delta and Aeromexico had pointed to other international joint ventures involving congested airports, including Tokyo Haneda, where antitrust immunity remained in place despite access constraints.
Delta Aeromexico Partnership
The dispute intensified in 2025 after the Trump administration accused Mexico of failing to comply with provisions of the U.S.-Mexico air transport agreement. U.S. officials argued that restrictions on slots at MEX disadvantaged U.S. airlines and gave Aeromexico an unfair competitive advantage because it controls a large share of the airport’s slots.
Mexico, however, has maintained that slot restrictions were linked to capacity pressures and required infrastructure work at the airport.
The disagreement prompted the DOT to issue a final order in September 2025 terminating the approval and antitrust immunity associated with the joint venture.
The order was due to take effect on January 1, 2026, but the Eleventh Circuit stayed it in November while the legal challenge proceeded, PYOK flagged.
The latest ruling now vacates the order itself rather than simply delaying its implementation.
What Happens Next
The decision does not permanently prevent the DOT from taking another action against the partnership.
The department could issue a new order, but it would need to address the shortcomings identified by the appeals court and provide a more consistent explanation for its market analysis.
For Delta and Aeromexico, the ruling provides greater certainty for a partnership that has operated for nearly a decade.
Delta said the joint cooperation agreement has expanded consumer choice and connectivity while supporting U.S. jobs and economic activity.
The airlines can therefore continue operating under their existing antitrust immunity for now. The ruling also gives the DOT a clear legal standard to meet if it seeks to revisit the partnership, making the case an important development for international airline alliances and U.S.-Mexico aviation policy.
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