In his inaugural address, President Barack Obama quoted the famous verse from Scripture that declares, “The time has come to set aside childish things.” Yet the first major environmental decision of his presidency, announced today, represents politics at its most childish and irresponsible. Obama is setting a disastrous course not just for future environmental policy, but for legal precedent as well.

At issue is whether the Obama administration should grant the State of California a waiver from federal law on automobile tailpipe emissions and allow the Golden State to set its own, more stringent standards on emissions and fuel economy (by and large, the same thing). California has sought this waiver for several years to comply with an ambitious mandate to curb greenhouse-gas emissions that the state legislature passed in 2006. The Bush administration denied California’s request, arguing that Washington should set standardized policies affecting the auto industry. Obama indicated throughout the campaign that if elected, he would grant California’s waiver. This week he put the administrative wheels in motion to do just that.

One might ask what the harm is in letting California pass its own laws and Californians deal with the consequences. In theory, it’s a good idea, and represents the essence of federalism’s guarantee of states’ rights. But in this case, advocates admit their aim is the complete opposite. They expect the effects of California’s stricter regulations to radiate far outside the Golden State’s borders. Indeed, they want to use California to circumvent federal law and, in the process, substitute Sacramento’s more onerous regulations for the ones that Congress passed in the 2007 energy bill.

It’s already quite costly for the nation’s automakers to meet federal mileage-efficiency mandates, which are uniform for the entire country. It would be cost-prohibitive for them to have to tailor their product lines to satisfy rules and regulations for 50 different states. Henry Ford showed that mass production is the key to making cars affordable for the common man. Even if California were the only state with its own separate standards, allowing it this privilege would toss Ford’s cost-lowering efficiencies out the window. Because of California’s enormous automobile market—its population is nearing 40 million people, and more than half are licensed drivers—carmakers would likely adjust their entire fleets to meet California’s strictures. The practical effect would be that cars manufactured in Detroit and the South would cost more and be made of lighter, less crash-resistant materials. Translation: higher sticker prices and more highway fatalities nationwide.

California’s law applies to cars sold, rather than made, in the state. The truth is that California no longer has any automobile industry of its own. Decades of aggressive anti-energy policies have caused energy prices in California to skyrocket, driving heavy industry to more business-friendly locales. Still, California wants to flex its bureaucratic muscle and regulate an industry located elsewhere.

For Governor Arnold Schwarzenegger and California’s environmental activists, that’s precisely the point. Green groups are hailing Obama’s move as bold, decisive leadership to address climate change, just as they celebrate California’s muscular approach to regulating greenhouse gas emissions. But far from being a courageous move from the new president, Obama’s decision just passes the buck. The idea is to implement in blunt fashion costly regulations that Obama is unwilling or unable to persuade Congress to endorse, despite heavy Democratic majorities in both houses.

It’s bad enough that the result will be more expensive cars and trucks. More costly still is the price paid by letting states dictate policies that are expressly the preserve of the federal government. One of Washington’s few explicit constitutional responsibilities is to regulate interstate commerce and prevent states or localities from stymieing or hijacking it. By granting California its waiver, and letting Sacramento’s out-of-touch political class make the laws that all Americans must follow, President Obama serves as an accomplice to a brazen theft of the federal government’s legal authority. If that’s not irresponsible, what is?

Max Schulz is a senior fellow at the Manhattan Institute.