Voter fraud has been an issue for the last six years - even since George W. Bush won an election that liberals were convinced he would lose. They spent the next several months trying to prove that the voting machines had been fixed. "Proofs" included comparing election night vote counts to pre-election and exit polls on the idea that polls are "exquisitely accurate". Grad students provided numerical analysis proving that it was mathematically impossible for districts with a majority of the population registered as Democrat to have voted Republican. There were allegations that voting machines were programmed to switch party-line votes to the wrong party. Two years ago the Simpsons Halloween show had this as its opening joke.
While liberals obsessed about voting machine fraud, conservatives worried about old-fashioned voter fraud involving paper ballots. There are a few ways that this can happen. People can vote more than once or under multiple identities. People who are not eligible can vote. Election workers can obtain extra ballots, mark them, and literally stuff the ballot box (the origin of the term). Conversely, ballot boxes from precincts known to favor the wrong party might disappear.
All of these happened in past decades. The question is if they are still happening? Some of these can be guarded against through proper controls - having observers from both parties present at all times, using tamper-resistant locks, etc.
The hardest thing to guard against is the ineligible voter. This is especially difficult in areas that allow same-day registration.
But wait, says Christopher Beam from Slate. Why would anyone commit voter fraud?
Perhaps the strongest evidence against claims of widespread voter fraud is that it would make no sense. Imagine what you'd have to do to perpetrate such a scheme. You'd first have to recruit a large number of voters willing to cooperate, each of whom would risk five years in prison and a $10,000 fine. Then you'd have to get them all registered, which would require fake IDs and mailing addresses. (The mailing address would have to be real so they could receive their registration cards.) The names and addresses would then get checked against a central state database. If the database fails to find a match, the voter's registration gets flagged for a follow-up check of their Social Security Number or driver's license number. Then on Election Day, they'd have to show their fake ID again and lie to a poll worker's face. At each point—registration, the database check, voting—they'd run the risk of getting caught. And the more people involved in the scheme, the more likely someone slips up. All it would take is one unlucky person for the whole plan to unravel.
Beam is right - under this set of controls voter fraud would be very difficult. The trouble is that some states go to lengths to circumvent these types of controls. Same-day registration means that there is no time to check the information that the voter provided. In order to allow some degree of control, the ballot and the registration can be saved together as provisional. If everything checks out then the ballot is added to the count. If not then it is discarded.
While this seems like a reasonable compromise, voting rights advocates (who, strangely, always seem to favor Democrats) feel that it somehow discriminates against the unregistered voter. They want all ballots mixed together.
A related issue is what sort of ID is needed. Beam's example requires a Social Security card or a driver's license (opening the possibility of illegal aliens voting). Again, this is seen as oppressive by voting rights advocates. They insist that all that should be needed is for someone who can document residency to vouch for the new voter.
All of this has been implemented or proposed in several states.
In 2004 there were reports a group of people being bussed from precinct to precinct. They would be met by a local party member who would swear that everyone in the bus was a resident. They would then register, vote from a prepared list, and move on.
Beam asks why anyone would do this? Some close, high-stakes elections make it worth the risk. The 2000 presidential election was ultimately decided by around 500 votes in Florida. In 2008, Senator Al Franken and Representative Mary Jo Killroy lost on election night but won their seats in the recount.
Beam's final argument is that so few cases of voter fraud have been filed. This proves nothing. Voter fraud is very difficult to prove. In my example of the bus-load of voters, how would you ever find them, again?
So, what can be done? Voting machines need to be trustworthy so we should demand an audit of the programming that goes into them. We should be very careful about removing any controls that are designed to prevent fraud.
While it is true that a citizen's right to vote is important in a free society, it must also me remembered that any appearance of voter fraud can undermine a government's legitimacy.