Daniel H. Leff, Associate Washington, D.C.
Phone: +1 202.624.2546
1001 Pennsylvania Avenue NW
Washington, DC 20004-2595

Daniel H. Leff is an associate in Crowell & Moring's Washington, D.C. office, where he practices in the Environment & Natural Resources, Energy, and Antitrust groups. Dan represents and counsels clients in a number of industries, including oil and gas, chemicals, mining, telecommunications, manufacturing, and retail. 

Dan's environment & natural resources and energy practice focuses on litigation, permitting, and counseling under environmental statutes including the Clean Water Act, Clean Air Act, Endangered Species Act, Surface Mining Control and Reclamation Act, and National Environmental Policy Act (NEPA) (and state equivalents); challenges to administrative rulemaking; and advising clients on Department of Energy and Federal Energy Regulatory Commission (FERC) permitting and regulation under the Natural Gas Act, and state energy and utility statutes and regulations. His antitrust and consumer protection practice includes representing clients in merger reviews and investigations by the Department of Justice, Federal Trade Commission (FTC), and Federal Communications Commission (FCC), and representing clients seeking to recover damages in private antitrust litigation.

Dan's recent Environment & Natural Resources and Energy matters include:

  • Representing a coal mining company in Clean Water Act and SMCRA proceedings in Montana state court and before the Montana Board of Environmental Review.
  • Consulting a trade association on matters involving approval and permitting of LNG export facilities and gas pipelines, as well as federal and state regulations concerning the production, transport, and distribution of oil and gas.
  • Providing analysis of, and guidance related to, FERC, state PUC, and ISO regulatory issues in representing TransCanada in its purchase of Columbia Pipeline Group.
  • Representing a coal mining company in defense of a SMCRA case in parallel proceedings before the Court of Appeals for the Sixth Circuit and the Interior Board of Land Appeals.
  • Representing a coalition challenging Fish & Wildlife Service violations of the Endangered Species Act and its regulations.
  • Representing a coal mining company in an enforcement action brought by EPA and states under the Clean Water Act.
  • Representing an oil production company in a challenge to its Clean Water Act permit before the Environmental Appeals Board.

Dan's recent Antitrust matters include:

  • Representing TransCanada in its acquisition of Columbia Pipeline Group.
  • Representing United Technologies in its sale of Sikorsky to Lockheed Martin.
  • Representing AT&T Inc. in its acquisition of DIRECTV.
  • Counseling clients on potential sales and acquisitions.

Dan's other recent matters include:

  • Acting as lead litigation and trial counsel for a small business in litigation over a commercial lease in District of Columbia Superior Court.
  • Representing a major corporation in an FTC investigation of its sales practices.

Dan also maintains an active pro bono practice. Most recently, in a proceeding before Immigration Court, he obtained asylum for a client fleeing persecution and torture in Central Asia.

Dan received his J.D. from the New York University School of Law, where he was executive editor of the Journal of International Law and Politics. He received his bachelor's degree from Georgetown University's School of Foreign Service.

Previously, Dan designed, sold, and managed multi-million dollar international conflict mitigation, disaster recovery, corporate social responsibility, and training programs for government, military, and oil and gas clients around the globe.


Admitted to practice: District of Columbia, Massachusetts, New York


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Jan.22.2015 Crowell & Moring's Antitrust Group Featured in Global Competition Review's 15th Edition "GCR 100"
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