With climate change poised to fall off of the Environmental Protection Agency's agenda under President Donald Trump, one group is paying particularly close attention: The lawyers who fought over putting climate on the agency's agenda in the first place.

Until almost two decades ago, the EPA had never recognized its authority to regulate emissions that contribute to climate change.

Alexander Diana, Rhamelin

“It was a tool that was just sitting there,” recalled Joseph Mendelson, who is now a senior counsel at Tesla, the electric carmaker. “Nobody had yet taken the step to actually use that idea.”