Supreme Court gives green light for Colorado to make cars cleaner

Environment Colorado

DENVER—Environment Colorado hails today’s landmark decision as one of the most important environmental cases ever heard by the Supreme Court.

By a 5-to-4 vote, the Court ruled today that the Clean Air Act gives the U.S. Environmental Protection Agency the authority to regulate carbon dioxide and other global warming pollutants from cars. This gives Colorado a green light to follow suit of states such as Oregon and California that limit carbon pollution from cars under the Federal Clean Air Act.

“This is a green light for Colorado to make cars cleaner and cut global warming pollution,” said Matt Baker, Executive Director from Environment Colorado. “Colorado can and should join western neighbors such as Arizona and New Mexico by setting clear goals and a plan to cut global warming pollution.”

Both governors in Arizona and New Mexico have issued executive orders setting specific goals for cutting global warming pollution and plans for how to reach those goals – which included the adoption of a “Clean Cars” vehicle emissions standard.

“Today, Colorado just got another tool in our tool box for fighting global warming. Now, we just need to start using them,” said Baker. “Last week, Gov. Bill Ritter put one tool to use by signing a bill to double Colorado’s renewable energy standard to 20% by 2020 that will cut global warming pollution 11%. Colorado’s next step is to lay out a plan for achieving hard reductions in global warming pollution.

The Supreme Court also ordered the U.S. EPA to reconsider its decision not to regulate carbon dioxide emissions from cars. In the meantime, the ruling will have major implications for rules to reduce global warming pollution from cars Under the Clean Air Act, states may adopt California’s tailpipe emissions standards in lieu of minimum federal standards. Nine states have adopted California’s standards to reduce fleet-wide global warming emissions from new vehicles by 25 percent in model year 2009, rising to 30 percent in model year 2016.

Environment Colorado’s federal advocacy office, U.S. PIRG, is a petitioner in the case, along with a coalition of states, cities, and environmental organizations. For a complete list of the petitioners and other documents related to the case, go to and click on “Court Action.”