Which branch of our government has done the most to protect Americans from global warming? The Supreme Court made the answer to that question obvious Monday, ruling that the Environmental Protection Agency must do its duty and regulate carbon dioxide emissions, or give a scientific – not political – reason for not doing so.

The case was birthed by a number of states, rightly unsatisfied with the glacial pace of federal leadership, that passed their own more stringent emissions standards. The problem was that approval was needed to enforce the new standards, approval that was never going to come from the Bush administration and its political appointees heading the EPA.

The administration and the EPA clung to an exceedingly narrow reading of the 1970 Clean Air Act, which said that the EPA has a responsibility to regulate “air pollutants” but did not specifically mention carbon dioxide, the leading contributor to the greenhouse effect. Using this as an excuse in the face of rapidly growing scientific evidence about the dangers of global warming, the EPA refused to do anything about this issue of critical importance.

We’ve had nothing but dawdling from Congress on global warming for years, and though the decision was made by a close 5-4 vote, the Supreme Court has done a great service to our country, and the world, by requiring the EPA to actually protect the environment and all of us along with it. The United States is the largest producer of carbon dioxide worldwide, and while the EPA will probably attempt to drag its feet through the rest of President Bush’s term, this ruling is a milestone event in the fight against global warming.

As Justice Oliver Wendell Holmes noted, “Ö the State has an interest independent of and behind the titles of its citizens, in all the earth and air within its domain. It has the last word as to whether its mountains shall be stripped of their forests and its inhabitants shall breathe pure air.”

Finally, the word from our government has been the right one. How about a few more?