The conservative-heavy court had largely given Trump everything he desired – until now, when two of his three nominees turned his back on him

After an agonising year in which the US supreme court has stood aside and watched while Donald Trump has run roughshod over the constitutional separation of powers, the highest judicial panel has finally stirred itself to set boundaries on the president’s increasingly regal pose.

Friday’s supreme court ruling declared Trump’s sweeping tariffs unlawful, yanking from the president the bloodied cudgel which he has used to beat foreign friend and foe alike.

With midterm elections just nine months away, Trump has also been deprived of a key weapon in his second-presidency armory.

“At last,” exclaimed Barb McQuade, a law professor at the University of Michigan. The court had remembered “that Congress is a separate and co-equal branch of government … One of Trump’s favorite levers is removed from the arsenal of extortion.”