The Justice Department is threatening the Federal Reserve with a criminal indictment over the testimony of Fed Chair Jerome Powell this summer regarding its building renovations. It is a major escalation by the administration after repeated attempts by President Donald Trump to exert greater control over the independent institution. Trump has repeatedly attacked Powell for not cutting its short-term interest rate, and even threatened to fire him. Trump has also accused Powell of mismanaging the U.S. central bank’s $2.5 billion building renovation project. Firing Powell would threaten the Fed’s venerated independence, which has long been supported by most economists and Wall Street investors. Here's some background on why Fed independence has been protected.