On May 31, 2018, Ann Carlson, Cara Horowitz, Sean Hecht and Meredith Hankins of UCLA Law School's Emmett Institute on Climate Change and the Environment submitted a comment letter to the California Air Resources Board in response to their request for public input on possible amendments to the state's greenhouse gas vehicle emission regulations. The comment letter supports action by CARB to maintain the current stringency of California's vehicle emission program in the face of attempted weakening at the federal level.