Accusations of a connection between Barack Obama and ex-Weatherman Bill Ayers have recently been gathering steam in conservative journals thanks to Weekly Standard and National Review contributor Stanley Kurtz. For the uninitiated, the Weather Underground was a domestic terrorist group that grew out of the New Left in the '60s and '70s. The group sought to transform America into a communist nation. Obviously, Obama does not seek such a transformation, but relationships with people like Ayers do raise other questions. More to the point is that Mr. Kurtz, along with many other journalists and lawyers, is investigating files that were...