Diana Liebmann



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Education and Clerkships

J.D., University of Texas School of Law, 1996

B.A., Political Science, Minor in Chemistry, Southwestern University, 1993



District of Columbia

Court Admissions

U.S. District Court for the Western District of Texas

U.S. District Court for the Southern District of Texas

U.S. Court of Appeals for the Fifth Circuit


Diana Liebmann’s legal advocacy and regulatory experience have helped clients through multiple restructurings of the electric power markets in Texas, to create the rules for the evolving ERCOT market - the most vibrant and competitive market in the country. Diana understands the risks inherent in certain transactions under constantly changing market rules and dynamics. She has represented clients in analyzing and structuring power supply arrangements for both wholesale and retail sales, including assisting LNG facilities with structuring power transactions. Diana works on both utility-scale generation project development and with smaller projects including end use consumers on-site and back-up generation. She was instrumental in developing the current postage stamp transmission pricing mechanism in the Competitive Renewable Energy Zone proceedings to obtain access to markets for their generation in a $6 billion transmission build-out of the ERCOT market, in interconnecting on-site generation both with ERCOT and transmission and distribution utilities.

Diana’s broad transactional experience and in-depth focus on the details of wholesale and retail power regulation and market structure give her the ability to effectively guide clients with respect to structuring transactions, compliance, and in the investment and deployment of capital in electricity markets.

Diana leads the firm’s Power and Renewables practice, is a partner in the Capital Markets and Securities practice, manages the San Antonio office as its managing partner and is a leader in her community.

Diana is valued as a leading energy lawyer by Chambers USA, Chambers and Partners, and is described as a “utilities guru” with a “great understanding of the Public Utility Commission.” She has become a go-to lawyer for regulatory matters relating to the Public Utility Commission of Texas, the Electric Reliability Council of Texas, the Southwest Power Pool, the Federal Energy Regulatory Commission and in various other state commission, regional entity and North American Electric Reliability Corporation proceedings.


Chambers USA 2020

Chambers USA Recognizes 58 Haynes and Boone Lawyers

58 Haynes and Boone lawyers spanning 17 practice areas are featured in the 2020 edition of the Chambers USA legal directory published by Chambers & Partners.

Selected Client Representations

Diana has worked on regulatory matters, in rulemakings and contested cases, and completed transactional matters including:

  • Structured financial hedges for project financing.
  • Transmission Cost of Service (TCOS) applications.
  • Development of power supply arrangements for a LNG facility including generation supply and regulatory requirement applicable to same and power supply negotiations between the facility third party suppliers, customers, and retail electric providers and qualified scheduling entities.
  • Proceedings to implement wholesale and retail restructuring at the State Office of Administration Hearings, the Public Utility Commission of Texas, at the Federal Energy Regulatory Commission and with the Electric Reliability Council of Texas.
  • Rulemakings regarding transmission access and pricing.
  • Wholesale and retail power purchase and sale agreements, retail electric provider agreements, qualified scheduling entity agreements, qualified facility agreements, contracts with third parties regarding professional services, and power plant construction agreements; including EPC agreements, and power plant project finance documents.
  • Certificate of convenience and necessity proceedings.
  • Rate case proceedings.
  • Proceedings at ERCOT and the PUCT regarding ERCOT governance, congestion management, ancillary services, settlement, transmission and distribution losses, reliability must run, resource adequacy and market monitoring.
  • Proceedings to establish rules for Competitive Renewable Energy Zones including related rulemakings and contested cases.
  • Competitive matters and confidentiality issues involving Open Records and Open Meetings laws.
  • Litigation involving the application of the antitrust laws to the ERCOT market.
  • Sale of electric power facilities and generating assets.
  • Regulatory investigation and complaint proceedings before the Public Utility Commission of Texas and Texas Regional Entity.

Professional Recognition

  • Recognized by Best Lawyers, Woodward/White, Inc., as a "2021 Lawyer of the Year"
  • Recognized by Best Lawyers, Woodward/White, Inc., as a "2019 Lawyer of the Year"
  • Recognized by Law360, LexisNexis, as one of 10 Influential Women In Energy Law, 2018
  • Recognized by Chambers USA, Chambers and Partners, as one of the leading practitioners in Texas for Energy, 2011-2021
  • Recognized by Euromoney's Expert Guides, Legal Media Group, in Energy and Natural Resources, 2016 and 2018; Energy and Environment, 2017
  • Recipient of the Women in Energy award by Texas Lawyer, ALM Media Properties, LLC, 2016
  • Recognized in Best San Antonio Female Lawyers, San Antonio Scene, Scene Monthly, LLC, 2021
  • Selected for inclusion in San Antonio Business Journal's list of Who's Who in Energy, American City Business Journals, 2012-2015
  • Recognized by San Antonio Scene in Best San Antonio Lawyers for Energy & Oil & Gas, Scene Monthly LLC, 2015, 2020
  • Named a Rising Star by Law360, Portfolio Media, Inc., as one of the top 10 energy lawyers under 40 to watch, 2010
  • Named one of The Best Lawyers in America, Woodward/White, Inc., in Energy Law, 2006-2021; Energy Regulatory Law and Utilities Law, 2019-2021
  • Named a Texas Super Lawyers Rising Star, Thomson Reuters, in Utility Law, 2004-2008
  • Named a Texas Super Lawyer, Thomson Reuters, 2013-2020
  • Listed as one of 2015's Best S.A. Lawyers in Energy & Oil & Gas (15 or more years), San Antonio Scene Magazine, Scene Monthly, LLC
  • Selected by the San Antonio Business Journal, American City Business Journals, as one of its 40 Under 40 Rising Stars, 2008

Professional and Community Activities

  • Advisory Board Member, University of Texas Kay Bailey Hutchison Center for Energy, Law and Business
  • Member, San Antonio Bar Association Natural Resources Section (President 2006-2009)
  • Member, Energy & Sustainability Committee, Greater San Antonio Chamber of Commerce (Chairman 2011-2013)
  • Advisory Board Member, Greater San Antonio Chamber of Commerce
  • Member, Oil, Gas & Energy Resources Section of the State Bar of Texas (Council Member 2009-2012)
  • Member, Gulf Coast Power Association
  • Director, Arc of San Antonio, Inc. (President 2008-2009), serving individuals with developmental disabilities
  • San Antonio Bar Association
  • Electric Cooperative Bar Association
  • Texas Bar Foundation

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