WASHINGTON: The US Supreme Court announced this term’s most momentous decision on the term’s last day. Thursday’s 6-to-3 ruling, although it lacked the cymbal-crash clarity and political wallop of the 5-to-4 decision overturning Roe v. Wade, matters more. It blocks the Environmental Protection Agency (EPA) from claiming an enormously consequential power that Congress did not clearly grant and defends the Constitution’s essence: the separation of powers.

Overturning Roe has ignited 50 state debates about one subject: abortion. Stymying the EPA’s extravagant expansion of its mission has profound implications for the making of many federal policies. Thursday’s opinion, the writing of which Chief Justice John Roberts assigned to himself, might, like a boulder thrown into a pond, have large ripples.

The Clean Air Act authorizes the EPA to impose the “best system of emission reduction” for carbonemitting activities. The EPA construes this as authorization for it to — if this seems “best” — restructure the nation’s power sector by ordering “generation shifting” in electricity production from coal to natural gas and renewables (e.g., wind, solar).

Roberts, joined by Justices Alito, Barrett, Gorsuch, Kavanaugh and Thomas, invokes the “major questions” doctrine. It holds that when an executive agency claims a power to order changes of vast economic and political significance — e.g., the EPA’s proposed multibillion-dollar restructuring (mandatory capital investments, higher energy prices) of a huge sector of the economy — courts should be skeptical of such claims unless legislation clearly and explicitly authorizes it. Otherwise, the agency is illegitimately lunging beyond its law enforcement function.

The court has hitherto rejected the Food and Drug Administration’s claimed authority to regulate or even ban tobacco products, something Congress had not endorsed. And during the pandemic, the court rejected the Centers for Disease Control and Prevention’s contention that its mission to prevent the spread of disease gave it an authority, never mentioned by Congress, to impose a nationwide eviction moratorium.

Now, Roberts writes, the court is reluctant to find a sweeping power “lurking” in vague Clean Air Act language. There is little reason, Roberts writes, to think Congress, without clearly saying so, tasked the EPA, “and it alone, with balancing the many vital considerations of national policy implicated in deciding how Americans will get their energy.” The majority should have invoked the related doctrine that Congress cannot properly delegate to an executive agency essentially legislative decisions.

By pruning the EPA’s pretensions, the court has signaled a quickened interest in policing the separation of powers. If, as is desirable, the decision presages similar ones, they could, cumulatively, revive Congress by compelling it to resume its proper responsibilities. This would limit the excessive autonomy currently enjoyed by the executive agencies that are the increasingly autonomous, unleashed and unaccountable administrative state.

Justice Elena Kagan, joined in her barbed dissent by Justices Breyer and Sotomayor, says “the court has never even used the term ‘major questions doctrine’ before.” The court has, however, urged hesitancy when an agency asserts a “highly consequential power beyond what Congress could reasonably be understood to have granted.” The EPA’s claimed carte blanche to order unlimited “generation shifting” is surely a spurious power.

Progressives since Woodrow Wilson have aspired to marginalize Congress to insulate the “science” of public administration from politics. The aim is to emancipate supposedly disinterested experts to apply, without political supervision, supposedly neutral science for social betterment.

Hysteria is constant today, so hyperbole is, too — as when on June 20 The New York Times lead article — top of page one, columns five and six — warned readers to be frightened that the court might do what it in fact did Thursday. The Times said a ruling against the EPA could severely limit “the federal government’s authority” to reduce carbon dioxide from power plants. But the court’s Thursday decision did not diminish the government’s authority; it said the primary authority must be explicitly exercised by Congress, which (although progressivism often forgets this) is part of the government. The Times also warned that the EPA case could eviscerate the “federal ability” to address climate change. No, the court has only required that more responsibility be taken by Congress, which is (although progressives often regret this) a federal institution.

In 1887, Professor Woodrow Wilson of Bryn Mawr College wrote that the complexities of modern life demand government by expert administrators with “large powers and unhampered discretion.” On Thursday, the court served notice to Congress and executive agencies that modern complexities are not a sufficient reason for abandoning the Constitution’s separation of powers, which still governs those who govern us.