The Bush administration’s decision to deny California permission to regulate and reduce global warming emissions from cars and trucks is an indefensible act of executive arrogance that can only be explained as the product of ideological blindness and as a political payoff to the automobile industry.

The decision, announced Wednesday by Stephen Johnson, the administrator of the Environmental Protection Agency, overrode the advice of his legal and technical staffs, misconstrued the law and defied both Congress and the federal courts. It also stuck a thumb in the eyes of 17 other state governors who have grown impatient with the federal government’s failure to regulate greenhouse gas emissions and wanted to move aggressively on their own.

The Clean Air Act of 1970 gave California authority to set its own clean air standards if it first received a federal waiver. The law also said that other states could then adopt California’s standards. In 2004, California asked permission to move ahead with a law requiring automakers to reduce greenhouse gas emissions from new cars and light trucks by 30 percent by 2016. That would require improvements in fuel economy far beyond those called for in the energy bill signed this week.

Over the years, California has made 50 waiver requests to regulate smog-forming pollutants and other gases and has never been denied. This was the first request involving emissions of carbon dioxide and other greenhouse gases, which the Bush administration has steadfastly refused to regulate.