Yesterday, five environmental groups announced they will file suit against the Environmental Protection Agency over its recent revision to the national air quality standard for ozone, or smog. Although EPA tightened the public health standard, also known as the primary standard, for ozone to 0.075 parts per million (ppm), down from 0.084 ppm, the agency did not go as far as its scientific advisors had recommended. EPA's Clean Air Science Advisory Committee recommended the standard be set somewhere between 0.060 ppm and 0.070 ppm. Other advisory committees and countless independent scientists also recommended a standard lower than the one adopted. Because the Clean Air Act requires EPA to set the standard for ozone based solely on the best scientific evidence available, the decision to set the standard outside the recommended range puts the standard on shaky legal footing. The public welfare standard, also known as the secondary standard, is on even shakier footing. EPA decided to set the secondary standard identical to the primary standard, instead of adopting a separate standard tailored for the summer months when ozone levels are at their highest. The problem is, both EPA scientists, policymakers, and administrator Stephen Johnson wanted the summer standard because science shows that sensitive trees and plants could benefit. The White House Office of Management and Budget disagreed, and President Bush was brought in to arbitrate the dispute. Bush ultimately came down on the side of OMB. Bush and OMB paid no mind to the Clean Air Act, which requires EPA set a standard to protect public welfare if necessary and which invests in the EPA administrator, not the president, the power to make clean air decisions. (More on that here.) If the courts tell EPA they need to set a separate secondary standard, the decision will be a stinging rebuke to Bush's intervention and a forewarning to future presidents. We don't know why the White House opposed a separate secondary standard. Maybe it was funneling the concerns of industry. Maybe it was exercising its ideological opposition to environmental regulation. Maybe neither. Maybe both. Regardless of the rationale, a decision in favor of a separate standard will send a clear message for this and other rulemakings: A president's personal views do not trump the plain language of federal law. The organizations filing the suit are the American Lung Association, Natural Resources Defense Council, Environmental Defense Fund, National Parks Conservation Association, and Appalachian Mountain Club. They will be represented by Earthjustice, a nonprofit, environmental law firm.