President Donald Trump raised the global duty on imports into the United States to 15 per cent on Saturday, doubling down on his promise to maintain his aggressive tariff policy a day after the Supreme Court ruled much of it illegal. Trump said on his Truth Social platform that after a thorough review of Friday’s “extraordinarily anti-American decision” by the court to rein in his tariff program, the administration was hiking the import levies “to the fully allowed, and legally tested, 15% level.” Shortly after the court’s 6-3 ruling that rejected the president’s authority to impose tariffs under a 1977 economic emergency powers act, Trump had initially announced a new 10 percent global levy by invoking a different legal avenue. At the same time, the Republican launched an extraordinary...