Legal issues affecting the deployment of clean energy solutions are arising across the U.S. energy landscape. The Trump administration is scaling back industry-wide restrictions on greenhouse gas emissions, raising fundamental questions about Clean Air Act authority to drive down carbon emissions. Meanwhile, new clean energy and fossil-fuel-based infrastructure projects (e.g. gas pipelines; wind/solar projects) are encountering disparate regulatory treatment at the hands of federal and state agencies, raising contentious legal issues across a number of statutory frameworks. Major disputes also have broken out between federal and state authorities regarding the management of interstate electricity markets and state-based clean energy choices, putting in play fundamental questions regarding states’ clean energy rights and the appropriate treatment of environmental costs and energy subsidies. How these issues are addressed and, hopefully, resolved in a clean-energy-friendly manner - via regulatory activity, litigation, and/or statutory reforms - will have a material impact on the speed with which the U.S. transitions to a clean energy economy.