If you welcomed the news that Congress has backed away from a cap-and-trade plan this year, the latest Bloomberg Business Week gives you reason to return to your gloom.

The magazine reports on Environmental Protection Agency chief Lisa Jackson?s efforts to restrict carbon use through provisions in the Clean Air Act.

Even she agrees that regulation is inferior to legislation. It took a 2007 Supreme Court ruling to clarify that the 1970 law gave the agency the power to regulate carbon at all. One of Jackson’s first moves as EPA administrator was to take up the court’s invitation and declare carbon an environmental threat. Within weeks, she followed that with rules requiring automakers to boost fuel economy 5 percent a year and average 35.5 miles per gallon by 2016.

Those rules, effective Jan. 2, 2011, will mark the U.S.’s first-ever nationwide limits on greenhouse gas pollution. Now, having taken that step, Jackson by law must clamp down on other carbon sources. In an economic downturn, she hopes to avoid writing detailed diktats for small businesses, schools, hospitals, and apartment buildings?many of which emit enough carbon that broad-based rules could force them to install expensive equipment. That could be politically explosive in a midterm election year, letting Republicans charge that Obama is strangling the economy.

Instead, Jackson has moved cautiously by offering what she calls a “tailored” approach that exempts mom-and-pop dry cleaners and pizza parlors and initially regulates only power plants and oil refineries. And among those, only new or expanding plants need comply.

Even so, business groups, led by the U.S. Chamber of Commerce, are taking Jackson to court, saying she has no authority to regulate greenhouse gases under the Clean Air Act.

Regular readers of this forum will not be surprised.