The Delta Aeroméxico joint venture ruling handed down on 20 August 2026 has vacated a US Department of Transportation (DOT) order that would have forced the two carriers to dismantle their trans-border commercial partnership, allowing coordinated schedules, fares and capacity to continue uninterrupted. The 11th US Circuit Court of Appeals found that the DOT failed to adequately explain why it applied a narrower competition analysis than it had used in previous airline-alliance cases.
What the court found wrong with the DOT’s market analysis
When the DOT originally approved the partnership in 2016, it examined competition across the entire US-Mexico market and 1,687 individual city pairs. The department’s 2025 review, by contrast, focused primarily on conditions at Mexico City International Airport (MEX), which accounts for about 21% of flights between the two countries. The court found that the final order contained no updated airline market shares, no analysis of how those shares could change if the partnership continued, and no fresh assessment of individual city-pair markets.
‘The final order was arbitrary and capricious because DOT drastically departed from its uniform practice of analysing country-pairs and city-pairs without a reasonable explanation of why such analyses were not necessary in this case,’ the court stated. The bench also questioned why the DOT imposed an open-skies requirement on Aeroméxico and Delta Air Lines that it had not applied to comparable partnerships in other markets.
That inconsistency carries particular weight given the DOT’s own record on US-Japan alliances. According to Eckert Seamans, the department had previously granted antitrust immunity to two joint ventures between US and Japanese carriers to operate at Tokyo’s Haneda International Airport, yet applied no equivalent open-skies condition in those cases. The court’s scrutiny of that disparity formed a central strand of its reasoning.
Background: why the DOT moved to terminate the arrangement
The DOT’s September 2025 order to withdraw approval and antitrust immunity stemmed from a dispute over Mexican aviation policy. US officials objected to reductions in available slots at MEX and to the Mexican government’s decision to move cargo operations to Felipe Ángeles International Airport (NLU). The department argued those policies favoured Mexican carriers and restricted access for US airlines, amounting to a breach of the 2015 US-Mexico Air Transport Agreement.
The airlines were initially ordered to wind down cooperation by 1 January 2026, but neither carrier dismantled the joint venture. The 11th Circuit stayed the DOT order in November 2025, preventing it from taking effect while the legal challenge was heard. That stay meant the partnership continued to operate throughout the proceedings.
The antitrust immunity at the centre of the dispute allows Delta and Aeroméxico to coordinate commercially sensitive decisions (including prices, schedules and capacity) that would otherwise be prohibited under competition law. The arrangement also permits revenue sharing across flights covered by the agreement, going well beyond a conventional codeshare under which one carrier sells seats on another’s services without jointly setting fares or determining capacity.
A 2022 extension now confirmed to remain in force
The partnership has a longer regulatory history than the 2025 dispute alone suggests. The DOT granted antitrust immunity when the joint venture was approved in 2016 and subsequently extended that grant in 2022, according to Econic Partners. The joint venture began operating in 2017 and has become a core part of both carriers’ networks between the two countries. Delta also holds approximately 20% of Aeroméxico.
Both airlines welcomed the ruling. Aeroméxico confirmed that the joint venture and its antitrust immunity remain in effect, allowing the carriers to continue offering their coordinated network and services to passengers.
The Delta Aeroméxico joint venture ruling leaves the door open for the DOT
The court’s decision does not settle the underlying competitive question. The 11th Circuit ruled that the DOT had not adequately supported its decision, rather than determining that the joint venture is necessarily pro-competitive. The department could seek to terminate the arrangement again, provided it conducts a broader market analysis and addresses the methodological inconsistencies the court identified.
The DOT said it was reviewing the ruling and considering its legal options. That assessment will determine whether the department pursues a revised process or allows the partnership to continue under the immunity framework it has held since 2016.
