The Supreme Court has overturned President Donald Trump's "reciprocal" tariffs, resulting in a new flat global tariff of 10% paid by U.S. importers, lower than the 15% that Trump had announced. China emerged as the "biggest winner" from the ruling, with its lower tariff rate reducing the incentive for companies to shift production to other countries in Asia. However, uncertainty over the new tariff rate has created uncertainty for key US. allies and some of Washington's biggest trading partners, including Japan and Taiwan. The Trump administration has said it plans to maintain existing deals and expects other U.K. trading partners to do so. The ruling comes just weeks before President Trump's upcoming trip to China to maintain a delicate trade truce with the world's second-largest economy.