You may have read that a judge has ordered that Don McGahn, the former White House counsel, must testify in response to a Congressional subpoena. What you probably didn’t read in the impeachment press is that the sweeping ruling essentially eliminates a right to confidentiality between a President and his most senior advisers. “The primary takeaway from the past 250 years of recorded American history is that Presidents are not kings,” wrote Judge Ketanji Brown Jackson in a ruling late Monday that was hailed far and wide as a victory over President Trump’s claim that close advisers have immunity from...