Presidents are often remembered for their signature obsessions. Teddy Roosevelt had his trust-busting. Franklin Roosevelt had his New Deal. Ronald Reagan had his tax cuts. Barack Obama had his health care reform. Donald Trump? He seems determined to be remembered for firing the referees of the US economy.This month alone, Trump has delivered two unprecedented blows to America’s institutional independence. First came the dismissal of Erika McEntarfer, Commissioner of the Bureau of Labor Statistics, whose offence was presiding over a weak jobs report that dared to revise earlier numbers downward. Then, in a move that rattled financial markets, Trump abruptly announced the “effective immediately” removal of Federal Reserve Governor Lisa Cook, citing alleged misstatements in her mortgage paperwork.