NPR reports: The U.S. Supreme Court is set to hear arguments in an important environmental case today. It will consider whether to pause a federal rule obligating states to be “good neighbors.” At the heart of the dispute is a provision of the Clean Air Act that protects people and states subject to pollution that floats downwind from other states. These “downwind states” struggle to meet federal air quality standards, and their residents can face health complications due to pollution from afar. 

I would think a better question is why individual states are at liberty to establish lesser standards than others in the first place.  Can’t these mandates be made at a federal level?  A coal-fired power plant in Colorado emits the same lethal array of greenhouse gases, heavy metals, and radioactive isotopes as one in Alabama.

The U.S. Environmental Protection Agency and Its “Good Neighbor Policy”