President Trump seems dead set on blowing up the historic clean car peace treaty forged ten years ago between the automobile industry, the federal government, and leading states.

Bizarrely, the Trump team is barreling ahead to revoke California's ability to set emission standards—over the objections of the automakers themselves, who see themselves caught in multi-car pile-up in the nation’s courts. This will not end well, for the car makers or the administration.

I know because 12 years ago I helped defend the authority of states to set these important pollution standards.

Here’s why the Trump administration’s latest moves are headed for a crack-up.

Two Laws, Three Agencies

Federal laws give three agencies—the federal Environmental Protection Agency, the federal National Highway Traffic Safety Administration, and the California Air Resources Board—legal authority to regulate new cars, SUVs, pick-ups, and other light-duty vehicles:

The Clean Air Act charges EPA with setting national standards for new vehicles’ dangerous air pollution.

The Clean Air Act also recognizes California’s unique role as the nation’s leader in setting its own new vehicle pollution standards.

Another law, the Energy Policy and Conservation Act, gives NHTSA the job of setting standards to raise vehicles’ fuel economy and curb our dependence on oil.

The clean car agreements reached under President Obama in 2010 and 2012 settled a long dispute between car makers, the federal agencies, states, and environmental organizations over how these laws and programs fit together. The Obama administration set—and automakers agreed to—standards through 2025. The Trump administration is now preparing to flat-line the standards. According to news reports, tomorrow it will take the first step by revoking California’s authority to set its own standards.

Here, in a nutshell is why that’s headed for a legal crack-up:

The Supreme Court ruled in Massachusetts v. EPA in 2007 that both the Clean Air Act and Energy Policy and Conservation Act apply to new cars, serving independent pollution control and fuel economy objectives. The Court stated that EPA’s and NHTSA’s duties “may overlap, but there is no reason to think the two agencies cannot both administer their obligations and yet avoid inconsistency.”

A closer look at the two statutes shows how they avoid inconsistency. Over nearly half a century, Congress has crafted the two laws so that pollution control comes first. In the historically rare situations when pollution control technology hurts fuel economy, the fuel economy law itself tells NHTSA to step back and soften its standards. Typically, however, the technology to clean the air and save fuel works hand in hand. Here, the technology for cutting cars’ climate pollution helps achieve greater fuel economy. In neither case can NHTSA block EPA’s or California’s pollution standards.

Let me trace this legal history in a bit more detail.

The Clean Air Act and California

In the 1960s California began curbing dangerous air pollution from automobiles as it dealt with its smog crisis. The state set the nation’s first engine emission controls in 1961 and the first tailpipe emission standards in 1967.

In the latter half of the 1960s, Congress moved to establish federal tailpipe pollution standards. At the same time, the 1967 Air Quality Act and the 1970 Clean Air Act recognized California’s unique role as the nation’s leader in setting pollution standards for motor vehicles by providing California with authority to set and enforce its own standards.

Section 209 of the Clean Air Act empowers California to set its own emission standards for new motor vehicles, requiring only that California get a “waiver” from the federal EPA that can be denied only in the most extreme circumstances. In 1977 Congress expanded the state role, adding Section 177 of the Act to allow other states to choose California’s car standards over federal ones. Thirteen other states have adopted California’s standards.

Section 209 says EPA must grant California the waiver if the state’s standards are “at least as protective of public health and welfare as applicable Federal standards.” EPA has very narrow legal grounds to deny a waiver. EPA granted dozens of waivers to California since the 1970s.

Congress specifically designed Section 209 to give California great latitude to set “standards on automobile emissions which may, from time to time, need to be more stringent than national standards,” recognizing the state’s need for deep emission reductions and the value of pioneering new controls in the California market and in other states that elected the same standards.

“Congress consciously chose to permit California to blaze its own trail with a minimum of federal oversight,” the D.C. Circuit Court of Appeals ruled in the 1979 decision Ford Motor v. EPA.

CAFE and Its Relationship to Clean Air

After the oil embargo of 1973-1974, Congress passed the 1975 Energy Policy and Conservation Act (EPCA) and charged the National Highway Traffic Safety Administration with setting fuel economy standards, which are known as the Corporate Average Fuel Economy Standards, or CAFE. The law aimed to reduce U.S. dependence on oil.

From the very start, however, the fuel economy law gave precedence to meeting clean air standards—both the EPA’s and California’s.

The 1975 law set out specific fuel economy standards for the late 1970s. It also addressed the possibility—real for the first generation of pollution control technology, but no longer true—that meeting California and EPA standards could reduce fuel economy. To address this conflict, EPCA provided that NHTSA should soften the fuel economy standards if necessary to assure that "federal" pollution standards were met. And here’s the key: Under EPCA if a California standard has an EPA waiver under Clean Air Act Section 209, it was expressly considered a “federal” standard.

In subsequent amendments to EPCA, Congress has always kept California standards in the basket of standards considered “federal” for purposes of the fuel economy law. (Now they are called “other motor vehicle standards of the Government,” but the meaning is the same.)

In 2007, federal courts in California and Vermont rejected auto industry lawsuits that claimed that the federal fuel economy standards preempt California’s clean cars program. Those cases hinged on the same arguments that the Trump administration is making now. (I was part of the legal team on these cases.)

The Vermont federal court held that state law is “not preempted where the required increase in fuel economy is incidental to the state law's purpose of assuring protection of public health and welfare under the Clean Air Act,” the court ruled in Green Mountain Chrysler Plymouth Dodge Jeep v. Crombie.

The court held that the California waiver “is entirely consistent with the language of the statutes, the House and Senate reports that accompanied the legislation, and NHTSA's practice of taking California standards into consideration when setting CAFE standards.”

If more proof were needed, in 2007 Congress adopted the Energy Independence and Security Act. As that legislation came to final passage, the Bush administration pleaded for amendments to overturn the court decisions, including the Supreme Court’s decision in Massachusetts v. EPA. Congress did precisely the opposite. It amended the fuel economy law to further confirm that fuel economy standards do not preempt federal and state emission standards.

As Greg Dotson, a former House staff member and now University of Oregon law professor, writes in a forthcoming analysis, "Congress had repeatedly, publicly and clearly rejected proposals to expressly preempt the states from adopting and enforcing greenhouse gas emissions standards. Congress had even rebuffed a request for preemption from the President [Bush] himself."

Trump’s Preemption Will Fail

Despite this statutory history and the multiple court decisions—and over the objections of the automakers—the Trump administration is trying once again to run the preemption playbook. NHTSA and EPA are about to announce that the fuel economy law preempts California’s standards.

It won’t work any better this time.

California, other states, and environmental organizations are ready to take those agencies to court. Together, we’ll block this latest Trump attempt to flout our laws and rollback vital climate protections.