Mexican second division clubs from the Liga de Expansión have filed a lawsuit against the top flight Liga MX and the Mexican Football Federation (FMF) regarding the return of promotion of relegation, sources confirmed to ESPN. The Athletic first reported on Tuesday that the case was filed at the Court of Arbitration for Sport (CAS) by 10 Liga de Expansión teams. According to ESPN sources, a majority of Liga de Expansión clubs with voting rights in the General Assembly, which aren't in the process of being sold, united to reinstate promotion and relegation for the 2025-26 season. The FMF said in a statement Tuesday that it "has not been notified of any proceedings against it by the Court of Arbitration for Sport. If notified, we will present our stance to the corresponding authorities." The primary argument stems from a previous decision by CAS that allowed a temporary suspension of promotion and relegation within Liga MX for six years, with the anticipation of that decision lifting in 2026. Whether that returns for the upcoming 2025-26 season, or 2026-27, remains a point of contention for all parties involved. Liga MX's next General Assembly is set to take place on May 26, one day after the second leg of this season's 2025 Clausura final between Toluca and Club América. The possible return of promotion and relegation is currently scheduled to be discussed by stakeholders. One day later, a separate General Assembly will be held by Liga de Expansión sides. The official pause on promotion and relegation was cemented in 2020 during the uncertainty that COVID-19 presented to Mexican soccer. In response to second division clubs asking for financial help, a deal was set with Liga MX for providing annual payments to the second division, but with the caveat of temporarily suspending promotion and relegation.