People / Diana Liebmann
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Diana Liebmann

Partner | Administrative Partner - San Antonio

Diana Liebmann is valued as a “utilities guru” and a “leading name” in energy law (Chambers USA, 2021 (Chambers and Partners)). Diana’s broad transactional experience and in-depth focus on the details of wholesale and retail power regulation and market structure enable her to effectively guide clients with respect to structuring transactions, compliance, and in the investment and deployment of capital in electricity markets. She leads the firm’s Power and Renewables Practice Group and is the managing partner of our San Antonio office.

Clients have relied on Diana’s legal advocacy and regulatory experience to guide them through multiple restructurings of the electric power markets in Texas. Diana offers clients an unusual synergy between her transactional work and her experience creating the rules for the evolving ERCOT market.

Diana understands the risks inherent in certain transactions under constantly changing market rules and dynamics. Clients seek Diana’s counsel in analyzing and structuring power supply arrangements for both wholesale and retail sales, including power generators, power marketers, congestion revenue rights holders, electric cooperatives, municipally owned utilities, retail electric providers and qualified scheduling entities (QSEs), and hedging and risk mitigation strategies. Diana works on both utility-scale generation project development (including conventional, renewable, and storage projects), and with smaller projects (including distributed generation, distributed energy storage, and end use consumers’ on-site and backup generation).

Diana is also a go-to lawyer for clients facing 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. She was instrumental in developing the current postage stamp transmission pricing mechanism and in the Competitive Renewable Energy Zone transmission proceedings to obtain access to markets for renewable generation.

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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 Affiliations and Engagements
  • 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

Awards and 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



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

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


District of Columbia


Court Admissions

U.S. Court of Appeals for the Fifth Circuit

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

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

Press Release
Haynes Boone Recognized in 2022 Best Lawyers in America Guide
August, 19 2021

Haynes and Boone, LLP had another impressive showing in The Best Lawyers in America directory published by Woodward/White, Inc., with a cross section of lawyers from offices across the country recognized in the 2022 edition. The guide includes more than 100 firm lawyers from the Austin, Charlotte, Chicago, Costa Mesa, Dallas, Dallas-North, Denver, Fort Worth, Houston, New York, Palo Alto, San Anto [...]