The US Supreme Court told Donald Trump on February 20 that the tariffs he has used to try and bend the world to his will are unlawful. Tariffs are taxes and it is not for the president to impose them. According to the US constitution, Congress holds the power of the purse.

Trump relied on the terms of a 1977 law designed to address national emergencies, the International Emergency Economic Powers Act, to impose the majority of his tariffs. The court held that this law did not provide Trump with the legal authority to impose them.

In a post on social media following the court’s decision, Trump called the justices who ruled against him a “Disgrace to our Nation”. And he has subsequently announced that he will rely on another law, section 122 of the 1974 Trade Act, to impose worldwide tariffs of 15%.

But even if Trump’s use of that law survives legal challenge, these tariffs would be time limited. The act says that after 150 days the tariffs would continue only if Congress says so. Trump disagrees, saying in his State of the Union address on February 25 that “congressional action will not be necessary”.

Trump is a would-be “strongman” leader. Like all strongmen, his aim is to concentrate political power in himself and those closest to him. Since returning to........

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