Democrats have spent weeks making the case that the Russia-Trump probes need to continue, piling on demands for more witnesses and documents. So desperate is the left to keep this Trump cudgel to hand that Senate Intelligence Committee Democrats have moved toward neo-McCarthyism.

If that sounds hyperbolic, consider an email recently disclosed by the Young Turks Network, a progressive YouTube news channel. It’s dated Dec. 19, 2017, and its author is April Doss, senior counsel for the committee’s Democrats, including Vice Chairman...