Ana S. Pirnia | People | Arnold & Porter

Ana Pirnia advises clients on complex disputes, regulatory matters, and strategic investments across the energy, infrastructure, and international business sectors. Her practice combines experience in international arbitration, commercial litigation, and energy-sector counseling, including matters involving electric power generation, natural gas infrastructure, LNG supply, telecommunications networks, mining projects, and major infrastructure developments.

Ana represents sovereign States and multinational corporations in investor-State and commercial arbitrations under the ICSID, UNCITRAL, ICC, LCIA, AAA, and other arbitral rules. She has served as counsel in disputes involving hydroelectric facilities, natural gas pipelines, LNG supply agreements, mining investments, telecommunications networks, and major infrastructure projects throughout Latin America and beyond. Her experience spans jurisdictional challenges, treaty interpretation, provisional measures, security for costs applications, witness examinations, damages issues, and merits proceedings. Her experience includes the first reported dismissal under ICSID Arbitration Rule 63(6), complete victories for sovereign clients in disputes exceeding billions of dollars, and multiple dismissals of claims arising from energy and infrastructure investments.

In addition to her disputes practice, Ana advises clients on energy regulatory and infrastructure matters, including electric transmission, large-load power procurement, data-center development, interconnection frameworks, and related project-planning considerations. She regularly analyzes developments affecting power markets, transmission access, grid reliability, and infrastructure investment, helping clients evaluate regulatory, commercial, and project-development risks associated with large-scale energy assets.

A native Spanish speaker, Ana works extensively on matters involving Latin America and frequently conducts factual development, witness preparation, and legal analysis in both English and Spanish. She earned her J.D. from Columbia Law School and her M.A. in International Economic Law from Sciences Po in Paris.

Focus Areas

Experience

Gasoducto Sur Peruano S.A. En Liquidación v. Republic of Peru (ICSID Case No. ARB/24/29). Counsel for the Republic of Peru in a pending ICSID arbitration concerning a natural gas pipeline project. The case involves complex issues of sovereign risk, infrastructure investment, and treaty protections in the energy sector.
José Alejandro Hernández Contreras v. Republic of Costa Rica (ICSID Case No. ARB(AF)/25/3). Counsel for the Republic of Peru in a third ICSID Additional Facility arbitration initiated by a Venezuelan investor involving a dispute in the telecommunication sector
Counsel for a U.S. company in an ICC arbitration concerning alleged breaches of risk and revenue-sharing agreements within the aerospace industry.

Sacyr S.A. v. Republic of Panama (ICSID Case No. UNCT/18/6). Successfully represented the Republic of Panama in a high-stakes UNCITRAL arbitration brought by Spanish construction firm Sacyr S.A. under the Panama–Spain BIT. The dispute arose from the Panama Canal expansion project, where Sacyr alleged treaty violations related to cost overruns and contract breaches. The tribunal dismissed all claims, finding they were contractual in nature and not attributable to the State, and awarded Panama over $6.3 million in costs.
José Alejandro Hernández Contreras v. Republic of Costa Rica (ICSID Case No. ARB(AF)/22/5). Successfully represented the Republic of Costa Rica in an investment arbitration brought by José Alejandro Hernández Contreras, arising out of the non-renewal by Costa Rica's electricity regulator of a contract with a local telecommunications company, and involving claims of $25 million. In March 2025, the arbitration was terminated at Costa Rica’s request due to deficiencies in the claimant's offer of security for costs. This case is the first reported dismissal under ICSID Arbitration Rule 63(6).
Latam Hydro LLC and CH Mamacocha S.R.L. v. Republic of Peru (ICSID Case No. ARB/19/28). Successfully represented the Republic of Peru in an investment arbitration filed at ICSID by Latam Hydro LLC and Mamacocha S.R.L. under a contract as well as the U.S.-Peru Trade Promotion Agreement, involving a dispute in the hydroelectric power sector. All claims against Peru were dismissed.
Lupaka Gold Corp. v. Republic of Peru (ICSID Case No. ARB/20/46). Represented the Republic of Peru in an investment arbitration filed at ICSID by Lupaka Gold Corp. pursuant to a bilateral investment treaty arbitration, involving a dispute in the mining sector and claims of over $100 million.
Kaloti Metals & Logistics, LLC v. Republic of Peru (ICSID Case No. ARB/21/29). Successfully represented the Republic of Peru in an investment arbitration filed at ICSID by Kaloti Metals & Logistics, LLC pursuant to a bilateral investment treaty arbitration, involving a dispute in the mining trade sector and claims of over $150 million. All claims against Peru were dismissed, and the arbitral tribunal ordered the claimants to reimburse Peru for the totality of its legal fees and expenses and of its arbitral costs.

Successfully represented a Virginia-based non-profit in an arbitration dispute under AAA Rules with a client management service provider.
Successfully represented a company and its subsidiary in an ICC arbitration dispute over alleged breaches of agreements for the supply of Liquified Natural Gas.
Successfully represented a UAE-based owner and developer of luxury hotels in LCIA arbitration dispute with branded management company and services provider.
Represented a minority hedge fund partner in complex dispute with majority partners under several agreements under ICDR Rules of Arbitration.
Counsel for individual in white collar criminal investigation involving OFAC sanctions.