A few weeks ago, President Donald Trump was an outwardly happy man because of the utterance of one solitary word from the lips of special counsel Robert Mueller to one of Trump's lawyers. The word that thrilled the president and his legal team was "subject." It seems that Mueller and one of Trump's lawyers had been negotiating the terms under which the president would submit to an informal interrogation by Mueller and his team of prosecutors and FBI agents. Mueller's request for such an interview was not unusual. Investigators are usually looking to trap an unwary potential defendant into lying...