The separation of powers is a core principle of American governance. Today, in Trump v. Slaughter, the Supreme Court heard arguments about how far that separation extends, and how much control the president has over officers of the executive branch.

Rebecca Slaughter was first nominated to the Federal Trade Commission (FTC) by Donald Trump in 2018, and renominated to that office by Joe Biden in 2023. But second-term Trump had a different opinion of Slaughter than he did seven years earlier. In March this year he fired her because, in his view, her “continued service on the FTC is inconsistent with my Administration’s priorities”.

There were many such firings early in his second term, and several were not legally controversial, even if they did spark predictable outrage from Trump’s political opponents. But the FTC position, like those of many of the so-called “independent agencies”, is a different animal, legally. Or, at least, it was designed to be.

The FTC was created during the Progressive Era, when Congress and President Woodrow Wilson introduced the idea that the complexities of the modern economy required scientific management by experts, not political appointees who would change from one administration to the next. This kind of technocratic government, they imagined, would be wholly apolitical and merit-based — a nice idea, if one that is largely divorced from the realities of politics and human nature.

FTC commissioners are therefore appointed for a seven-year term. No more than three of the five commissioners can be from the same party, and they are — according to the terms of the 1914 FTC Act — only removable for “inefficiency, neglect of duty, or malfeasance in office”.

The system functioned, as long as no one pushed too hard against the norms surrounding it. One president who did try to force the issue was Franklin Roosevelt, when he fired Republican William Humphrey from the FTC in 1933 for reasons which sound very similar to Trump’s: “The aims and purposes of the Administration with respect to the work of the Commission can be carried out most effectively with personnel of my own selection.”

Roosevelt lost that case, Humphrey’s Executor v. United States, but the principle the court established there has been under attack lately as a violation of the separation of powers.

Almost a century later, Trump v. Slaughter revisits that dispute between the Constitution’s language about the executive (“The executive Power shall be vested in a President of the United States of America”) and what mainstream opinion has come to think it means (Congress can make some agencies governed by quasi-independent experts who aren’t just tools of the White House).

Liberal Justice Elena Kagan noted the contradiction during oral arguments this morning, explaining that Congress has essentially made a bargain in the past century, giving the agencies lots of work to do that is not traditionally executive. In doing so, they made it clear that these nominally executive agencies are not under the control of the White House — to take away half of the bargain would mean we end up with massive uncontrolled power in the hands of the president. Fellow liberal Justice Ketanji Brown Jackson went further, saying that independent agencies exist because people think some issues should be determined by independent experts.

That blinkered establishment way of thinking — “my experts are neutral, yours are political” — may have worked in a high-trust era, yet it is uniquely unsuited to a time when trust in institutions and experts has been harmed and diminished in countless ways. It is also contrary to the “saving democracy” rhetoric the Left typically favours when opposing anything the (elected) president does.

Government in the United States has changed a great deal since 1789, and the arguments in Slaughter reflect that shift from a tiny and unobtrusive federal government to a bureaucracy of a million-plus employees. Adding independent agencies was a reflection of the legal and political consensus at the time on how the nation should be governed. It probably still is. The problem the court confronts today, though, is that the congresses of the Progressive Era and beyond never bothered to amend the Constitution to match their vision.

Since Humphrey’s Executor was decided in 1935, the political establishment largely conformed to that vision, whether it was written into the Constitutional text or not. But norms fade while text endures. Trump’s new-style executive rejects the old technocratic vision. Judging by today’s arguments, the Court may join him.