Leslie T. Thornton

Advisory Board Member

Leslie Thornton has spent more than 30 years as a senior presidential policy advisor, a law firm partner and a senior legal and management executive for a multi-billion-dollar energy company. She was elected on Jan. 1, 2019, to the board of directors of Southwest Gas Holdings. She also is a Board Leadership Fellow for the National Association of Corporate Directors. She has served for 13 years as a Director for Career Education Corporation, Inc., a billion-dollar publicly traded higher education company.

Thornton is a sought-after speaker on cyber security, corporate leadership, legal diversity and numerous other topics. She has earned multiple awards and recognitions for her innovation, influence, leadership and community service.

Thornton retired in Nov. 2018 from WGL Holdings, Inc. and Washington Gas Light Company where she was Senior Vice President, General Counsel & Corporate Secretary. Under her leadership, she led the company from 2014-2018 through a $6.4 billion merger, including the negotiation of the merger agreement, public disclosures and regulatory approvals. Serving the company in general counsel capacities from 2011-2014, Thornton was responsible for the provision of legal advice and counsel on matters including M&A, cyber security, data security and data privacy, litigation, regulatory law, employment, labor, employee benefits issues, board of directors, as well as for providing advice and direction on various corporate projects.

During her WGL tenure, Thornton earned her Master of Laws degree in National Security Law with a cybersecurity focus and provided legal counsel on a broad range of issues including critical infrastructure cybersecurity and data protection. She has technical as well as experiential experience in national security cyber security issues. For the past seven years, Thornton has co-authored the chapter on Privacy and Security in the Thomson Reuters Annual Treatise on Successful Patterning Between Inside and Outside Counsel. Prior to WGL Holdings and Washington Gas, Thornton was a law partner at Dickstein Shapiro LLP (2004-2011) and Patton Boggs LLP (2000-2004).

In 1992, Thornton ran the Clinton-Gore ’92 campaign headquarters in Alexandria, Va., and served on a campaign task force. After the election, she served the U.S. Department of Education as Deputy Chief of Staff and Counselor to the Secretary. She later was a political and policy advisor to President Clinton for the 1996 presidential debates. After the ’96 election, Thornton returned to the U.S. Department of Education as Chief of Staff to the Secretary.

She began her law career in 1982 as a staff attorney at the Public Defender Service in Washington, D.C., as well as in litigation associate positions at two law firms.

In addition to a L.L.M. in National Security Law, Thornton holds a B.A. in Political Science from the University of Pennsylvania and a J.D. from Georgetown University Law Center.