The US president blocked former White House counsel Donald McGahn from testifying before Congress about the special counsel’s report on Russian election interference, prompting fresh threats of impeachment. The House judiciary committee held a brief hearing on Tuesday morning in McGahn’s absence, with an empty chair where he was supposed to sit. The committee chairman, Jerry Nadler, said subpoenas were 'not optional' and the committee would hear McGahn's testimony even if it had to go to court to secure it