Stakes high for the environment

The Trump administration is considering a new assault on American legal and constitutional structures by taking on federalism – and vehicle emissions.

Specifically, the Environmental Protection Agency reportedly will try to revoke a waiver that California has enjoyed for 45 years, which allows the state – and any state that wants to copy it – to regulate tailpipe emissions more stringently than the federal government does.

A revocation by President Donald Trump and the executive branch is almost certainly unlawful. The Clean Air Act expressly says that California must be granted the waiver if its emissions rules are ‘‘at least as protective of public health and welfare’’ as the federal government’s.

The Clean Air Act’s waiver provision is unusual – and it flows from federalism principles.

Under the Constitution, as a default, both states and the federal government share the capacity to regulate most activities. The states have an inherent regulatory power, known as the ‘‘police power’’. The federal government gets its power to regulate from Congress’s authority to make laws on matters affecting interstate commerce. State and federal power can overlap, as in the case of the punishment of drug crimes.

Because federal law is the supreme law of the land, according to the Constitution, federal law trumps state law when the two conflict.

Congress has a special power that allows it to deal with that conflict by barring states from regulating in areas where they might interfere with federal rules. This power is called ‘‘preemption’’: Congress ‘‘preempts’’ state law when it has occupied the whole field of regulation to the exclusion of the states. Sometimes Congress says expressly that it’s preempting state laws – sometimes the preemption is implicit.

The Clean Air Act is an example of federal preemption – in part. Section 7543 of the law says that no state ‘‘shall adopt or attempt to enforce any standard relating to the control of emissions from new motor vehicles’’. That includes ‘‘certification, inspection, or any other approval relating to the control of emissions from any new motorvehicle’’.

Yet as soon as the law takes away states’ regulatory power, it restores it to California. The law says the EPA administrator ‘‘shall... authorise California to adopt and enforce standards’’. It’s up to California to determine ‘‘that California standards will be, in the aggregate, at least as protective of public health and welfare as applicable Federal standards’’.

The only ways to block California from using its own standard are if the EPA administrator determines that the California rules are arbitrary and capricious or if ‘‘California does not need such... standards to meet compelling and extraordinary conditions’’. So long as Los Angeles has smog, the conditions are going to be compelling.

The historical reason for this design is that California had been regulating emissions long before the federal government got into the act.

But the structural reason is that California had the influence in Congress to make sure its regulatory power was preserved even after the Clean Air Act was passed. The true balance between state and federal authority is worked out in Congress, where the states can have a real impact on lawmaking.

Thus, it’s not up to the president to change the balance of power.

And that’s what Trump’s EPA is doing by considering the revocation of the waiver that has been in place since just after the law was passed in 1970.

There is some existing legal uncertainty about whether the waiver may be used by California to regulate greenhouse-gas emissions.

The best reading of the law is that it does extend to greenhouse gases. But what’s more important is for the executive branch to recognise that Congress has preserved California’s authority, and that it should respect that decision.