Nearly 100 years ago, the Supreme Court ruled unanimously that Democratic President Franklin Delano Roosevelt did not have unchecked power to replace commissioners on regulatory agencies set up by Congress to be insulated from presidential authority.

On Monday, facing a challenge by Republican Trump, the court decisively scrapped that precedent.

“Subordinates who exercise the president’s power are subject to removal by him,” Chief Justice John Roberts wrote in the majority opinion. “Then, and only then, can they remain accountable to the president, and the president to the people.”

In this ruling, the court’s justices divided into familiar groupings. All six conservatives, three of whom were appointed by Trump, found in favour of the president. The three liberal justices, all appointed by Democrats, dissented.

The court’s decision will give Trump, and all future presidents, broad power to remove and replace regulators from dozens of key agencies with whom they disagree.

The Federal Trade Commission was directly at issue in this case (as it was in Roosevelt’s), but the precedent the court sets here will apply to regulatory bodies interpreting election laws, issuing communications policies, resolving labour disputes and establishing financial and environmental regulations.

By now, Americans are used to dramatic policy swings when a president of a different political party takes over the presidency – from Barack Obama to Trump to Joe Biden and back to Trump. This court’s decision is sure to supercharge that trend.

“Ninety years of precedent has been completely and unequivocally overruled,” Trump exclaimed in a Truth Social post after the decision, “greatly increasing presidential power at a time when it is most needed!”