AUGUSTA – Maine has officially joined California in a lawsuit aimed at forcing a decision over whether states can impose greenhouse gas emission standards for cars and light trucks, Maine Attorney General Steven Rowe said Friday.

Maine is one of 13 states that are joining in two lawsuits, one filed in U.S. District Court and the other in the U.S. Court of Appeals, Rowe said.

Maine has adopted California’s stringent emission standards, which are allowed by the Clean Air Act. But the Environmental Protection Agency has let nearly two years pass without acting on California’s request for a waiver allowing the rules to go into effect.

California asked EPA to grant its waiver in December 2005. EPA administrator Stephen Johnson said last summer that he would make a decision by the end of this year. The lawsuits aim to hold him to that schedule, Rowe said.

Maine’s move to intervene, along with 12 other states, as a plaintiff in California’s lawsuits, adds important support to California’s efforts.

“Maine has adopted a policy designed to combat climate change by controlling greenhouse gas emissions from automobiles sold in this state,” Rowe said. “The EPA must grant the waiver so we can enforce these laws and begin to reverse the effects of global warming.”

All told, 14 states have either adopted the California regulation or are in the process of adopting it: Arizona, Connecticut, Florida, Maine, Maryland, Massachusetts, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, Vermont and Washington.