was first elected to the Senate in November 1974, just three months after President Richard M. Nixon resigned. Congress and the nation were both shaped and scarred by the Watergate scandal, by the strain it placed on our democratic institutions, and the mistrust in government that ensued. Those years serve as a reminder that a democracy hidden from the people is no democracy at all. The parallels between then and now are many. In both sagas, a politically motivated theft — one a burglary, the other a hacking — led to an investigation described by the president as a “witch...