Washington(CNN)Donald Trump was right: He can get away with almost anything -- a factor that is likely to mean an even more unchained presidency over the next 18 months.All the reasons why Democratic efforts to check the President will likely fail were revealed in Attorney General William Barr's trial by fire on Capitol Hill on Wednesday and his refusal to submit to a second round before the fired-up House majority on Thursday.The drama also showed that in the short span of a White House term, given certain partisan conditions, the modern political system will find it almost impossible to constrain a President -- especially...