Begin here. The Southern Poverty Law Center has several articles on the subject of the “sovereign citizen movement.” If you talked to any member for five minutes, you’d think they were crazy too, except that there are allegedly as many as 300,000 of them.
Assuming evidence emerges that this is the source of Loughner’s views, the discussion needs to shift from “each individual is responsible for their actions” (as true as that is) to “these are not our views.” I look forward to conservatives making that explicit; it can only help the cause of peaceful discussion of political differences. The crucial question is: do you merely disagree with the political preferences of your rivals, or do you regard the existing political system as illegitimate? I suspect a big part of our current difficulties stems from studied ambiguity on this question, by far too many people.