WITH MARKETS gyrating from the tariffs Donald Trump has imposed on around 180 countries, only to pause some of the most punishing ones on April 9th, a conservative organisation has filed a lawsuit challenging an initial round of tariffs the president announced on Chinese imports in February, duties he has since escalated. The New Civil Liberties Alliance (NCLA), which counts Charles Koch, a right-wing billionaire, among its supporters, argues that the president lacked the authority to impose these levies. With Chinese goods still a prime target, the case retains its salience. Similar lawsuits against other tariffs could yet scuttle the boldest—and most destabilising—move of Mr Trump’s second term.