Many of President Donald Trump’s battles with the federal judiciary have pitted his administration against the policy judgments of Left-leaning district judges in hand-picked courtrooms across the country. These are battles of political will which have no place in a court of law. Yesterday’s ruling from the United States Court of International Trade is not one of those, however.

Instead, the three-judge panel’s ruling is a well-reasoned, originalist holding that reminds us why the separation of powers is at the heart of the American republic, and how it protects citizens from the arbitrary behaviour of government officials.

The specific issue under review was whether the International Emergency Economic Powers Act of 1977 (IEEPA) gives the President the power to impose any sort of tariff he wants, when he wants, where he wants. The larger question is whether Congress did — or even could — delegate such a sweeping power to any president. The answer to both of these questions, the court concluded, is “no”.

It’s as big a case as the Court of International Trade is ever likely to see, and the judges seem to have crafted their ruling with the knowledge that it would be read by an audience far wider than the usual legal specialists who practise before them. In it, we learn a brief history of trade, tariffs, and the president’s power over them. In brief, for more than a century Congress has let the executive branch fine-tune tariffs and make emergency adjustments when required. But never before has a president taken that power to mean that he can simply declare an emergency and thereby take power over international trade into his own hands.

The closest any president ever came to doing what Trump has done was in 1971, when Richard Nixon imposed emergency tariffs in response to an international crisis involving the convertibility of the dollar to gold. That was a serious problem which required drastic actions, but even then Congress deemed the “Nixon shock” too sweeping and too much of an executive power grab. Legislators responded by passing the IEEPA, which curtailed some of those powers.

Trump’s actions are far beyond anything Nixon did and, according to the court, far beyond what the law allows. And unlike in 1971, Trump’s response to the emergency he proclaimed (Americans dying of fentanyl overdoses) has no connection to the remedy (tariffs on foreign goods). Drug smuggling is basically unaffected by tariffs. Cartels aren’t bringing substances through the ports legally — and even if they were, making it 10% more expensive wouldn’t prevent Americans dying from overdoses.

The White House maintains that the tariffs provide leverage to make the other countries deal with drug smuggling on their end. That’s true, but it’s not what the law allows. Quoting Biden v. Nebraska, the court acknowledges that “the question here is not whether something should be done; it is who has the authority to do it.”

Choosing that case as authority is meaningful. Conservatives were rightly outraged when Joe Biden’s administration stretched a minor provision in a 50-year-old law to claim the president could forgive student-loan debt with the strike of a pen. Now Trump’s lawyers have claimed a similarly sweeping power on likewise flimsy pretexts. This case will be appealed, possibly to the Supreme Court, but we should not be surprised to see it upheld: it is in line with originalist ideas about presidential power. The only question will be whether the three liberal justices who would have allowed Biden’s power grab in that case will support Trump’s here.

Trump will want to spin this as more judicial obstruction by the Left, but this case is grounded in history and conservative jurisprudence. The better move might be to take the opportunity to restart the trade conversation, this time with Congress and America’s allies at the table. The President can drop the pretence that the tariffs have anything to do with fentanyl and get down to the real business of reshoring industry and containing the growing Chinese threat.