The U.S. District Court for Montana and U.S. Court of Appeals for the District of Columbia have both issued decisions suggesting that the “social cost” of greenhouse gas emissions must still be considered under the National Environmental Policy Act (“NEPA”) – despite President Trump’s desire otherwise.

In 2009, President Obama instructed federal agencies to create a metric for quantifying long-term economic damage to society from a project’s greenhouse gas emissions. These agencies have estimated that these “social costs” could be as high as $69 per metric ton of carbon dioxide released into the atmosphere. As part of President Trump’s March 28, 2017 executive order, this working group was disbanded, and individual agencies were directed to calculate social costs under 2003 Bush-era guidelines.

Two recent court decisions, however, may spur a response from the Trump administration. In Montana Elders for a Livable Tomorrow et al. v. U.S. Office of Surface Mining et. Al., (D. Mon. 2015), Case No. 9:15-cv-00106, environmental groups challenged an expansion to one of the largest coal mines in the country. On August 15, 2017, Judge Donald W. Molloy agreed with the plaintiffs that the social cost of carbon was a tool that should have been used to measure the project’s greenhouse gas emission impacts. In Sierra Club et al. v. Federal Energy Regulatory Commission et al. (D.D.C. 2016), environmental groups challenged approvals for a $3.5 billion fracked gas pipeline. The Court of Appeals for the District of Columbia agreed with the plaintiffs, finding that the Federal Energy Regulatory Commission should have attempted to quantify the downstream greenhouse gas impacts of the gas transported through the pipelines.

The Trump administration has not yet commented.