"Today's Supreme Court decision is a resounding victory for public health and a key component of EPA’s efforts to make sure all Americans have clean air to breathe," EPA Administrator Gina McCarthy said in a statement. "It serves to support the ongoing work to see that air quality in downwind states continues to improve. The Court’s finding also underscores the importance of basing the agency’s efforts on strong legal foundations and sound science. This is a big win for the nation’s public health and a proud day for the agency."
The majority decision was written by Justice Ruth Bader Ginsburg. The two dissenting justices were Clarence Thomas and Antonin Scalia. Justice Samuel Alito did not take part in the case.