Why the supreme court’s tariffs ruling is a win for world trade – but also tricky

The decision adds to economic uncertainty, as deals Donald Trump struck with other countries are upended

It is refreshing to witness the US supreme court recover its spine and stand up to Donald Trump's most extreme caprices. The 6-3 decision on Friday to strike down his barrage of tariffs on imports from virtually everywhere based on the preposterous argument that they addressed national emergencies will reassure the world that the US's system of government - based on the separation of powers, checks and balances, and the rule of law - has not collapsed entirely.

But let's hold the (imported) champagne. The court's ruling will not restore the United States to its former place as a reasonable, trustworthy player in the world economy. The rules-based economic architecture that underpinned the integration of the world economy over the decades that followed the second world war remains fractured. Trump is still intent on its disintegration. And he retains power to do so.