The US Supreme Court ruled Friday that Donald Trump exceeded his authority in imposing a swath of tariffs that upended global trade, blocking a key tool the president has wielded to impose his economic agenda. The conservative-majority high court ruled six-three in the judgment, saying the International Emergency Economic Powers Act (IEEPA) “does not authorize the President to impose tariffs.” While Trump has long used tariffs as a lever for pressure and negotiations, he made unprecedented use of emergency economic powers upon returning to the presidency last year to slap new duties on virtually all US trading partners. These included “reciprocal” tariffs over trade practices that Washington deemed unfair, alongside separate sets of duties targeting major partners Mexico, Canada and Chi...