Drop everything and read Justin Levitt’s piece in NYT’s “Campaign Stops.” A taste:

There are three big problems with mass challenges. The first is the accuracy of the underlying information. Sloppy efforts to match data from one system to another yield many mistakes: garbage in, garbage out. People listed as dead aren’t dead. People listed as moving haven’t moved. People listed as noncitizens aren’t noncitizens. People listed with disenfranchising convictionshaven’t been convicted of disenfranchising crimes. Or eligible citizens on the rolls are mistaken for people who are ineligible but not registered — like Florida Governor Rick Scott, flagged as dead in 2006 by a purge that confused him for another Floridian with the same name and date of birth. Mistakes like these are far more common than most of us would assume.

The second problem is that some citizen vigilantes see the law as they want it to be, not as it is. They hunt voters registered at business addresses, ignoring the fact that small business owners or managers may live where they work. They hunt immigrants, ignoring the fact that noncitizens may have become naturalized. They hunt students and others in group housing, ignoring the fact that legal residence may not be intuitive. They target, in short, situations that they deem unfamiliar — forgetting that unfamiliar is not the same as unlawful.

The law they think they are helping to enforce is the law of their gut, not the law on the books. And at the most extreme, they even impersonate real law enforcement personnel to do so.

The third problem is the result of this wholly predictable inaccuracy. Belated mass challenges to registration rolls suck time away from overworked and underpaid officials desperately trying to make sure that the elections run smoothly and they pull eligible citizens away from jobs and families into unnecessary legal hearings. Mass challenges to absentee ballots leave legitimate voters with little practical chance to defend themselves. Mass challenges at the polls bog the process down, creating excessive and confrontational lines that make voting a gauntlet rather than a civic rite.