Motion to intervene in United Mexican States v. Lion

Sovereign Arbitration Advisors represents intervenor in ICSID Additional Facility award vacatur proceedings

Luis Parada and Csaba Rusznak are representing a Mexican businessman in connection with proceedings in the U.S. District Court for the District of Columbia seeking vacatur of an ICSID Additional Facility award rendered in Lion Mexico Consolidated L.P. v. United Mexican States (ICSID Case No. ARB(AF)/15/2).

As a non-party to the underlying arbitration, our client has filed a motion to intervene in the U.S. court proceedings for the purpose of supporting the Respondent State’s petition to vacate the underlying arbitral award. 

This is the first known motion to intervene in post-award litigation proceedings by a non-party in the investor-State arbitration context. 

After the District Court denied the State's petition to vacate the award, the Court also denied our client’s motion to intervene. The State and our client appealed the decision in December 2024. A three-judge panel from the United States Court of Appeals for the District of Columbia Circuit heard oral arguments on November 3, 2025.

A decision on both appeals is expected during the first half of 2026.