A Supreme Court ruling that gutted the legal foundation for much of US President Donald Trump’s tariff regime has left Asian trading partners scratching their heads about the future of trade deals struck with Washington over the past 12 months. America’s apex court ruled on Friday that the International Emergency Economic Powers Act (IEEPA) – which Trump had used to impose sweeping “reciprocal” tariffs since his “Liberation Day” proclamation last April – did not grant the president the power to...