The U.S. Supreme Court blocked a lawsuit yesterday aimed at reducing greenhouse gas emissions, holding that because the power to regulate emissions had been delegated to the Environmental Protection Agency under the Clean Air Act, federal common law did not apply.
Although the ruling limited the threat of tort liability, there are some positive implications for U.S. climate policy, writes Yale Law Professor Douglas Kysar in Nature. But along with the good comes not just the “bad” but the “downright ugly,” Kysar writes.
The “good” is that the opinion “solidified the court's landmark 2007 conclusion that the EPA has the power to regulate carbon dioxide as a pollutant.” This means that if Congress attempts to limit the EPA’s power in this area, these lawsuits could be reinstated, he explains. The court also left open state common law as an avenue for pursuing such suits.
The “bad” is that lawsuits under federal common law are foreclosed even if the EPA never exercises its power to regulate, so long as that power is not explicitly repealed by Congress.
And in the category of “downright ugly,” is the opinion’s overt skepticism about the science of climate change, Kysar writes, which likely influenced their decision in this case. The opinion suggests readers explore “views opposing the EPA” by reading a profile of Freeman Dyson, “the theoretical physicist whose controversial views on climate change have been widely promoted by the climate-skeptic community.”
He continues:
of delta smelt, a small fish endemic to California, against challenges from the Pacific Legal Foundation, which argued that the protections diminished water exports from the Delta, The Sacramento Bee 
"Forty years ago today, twenty million Americans - fully one-tenth of our country's population at the time - came together to express the wakeup call that was Earth Day 1970," 
he EPA's 
Georgetown University law professor