A 2006 study by the Brennan Center for Justice at the New York University School of Law concluded that individual voter fraud is extremely rare, largely because it's close to worthless as a way of influencing an election. A person who attempts it risks years in prison and thousands of dollars in fines just to cast a single fraudulent vote.
There is no documented wave or trend of individuals voting multiple times, voting as someone else, or voting despite knowing that they are ineligible. Indeed, evidence from the microscopically scrutinized 2004 gubernatorial election in Washington State actually reveals just the opposite: though voter fraud does happen, it happens approximately 0.0009% of the time. The similarly closely-analyzed 2004 election in Ohio revealed a voter fraud rate of 0.00004%.
Many vivid anecdotes of purported voter fraud have been proven false or do not demonstrate fraud. Although there are a few scattered instances of real voter fraud, many of the vivid anecdotes cited in accounts of voter fraud have been proven false or vastly overstated. In Missouri in 2000, for example, the Secretary of State claimed that 79 voters were registered with addresses at vacant lots, but subsequent investigation revealed that the lots in question actually housed valid and legitimate residences. Similarly, a 1995 investigation into votes allegedly cast in Baltimore by deceased voters and those with disenfranchising felony convictions revealed that the voters in question were both alive and felony-free.
Furthermore, only a fraction of the tiny number of real instances of voter fraud would be prevented by requiring a photo ID.
But so what? What's the harm in asking people to show an ID, as we do at a bank or when going through airport security? Not much -- if you happen to have an one. Most of us do, but quite a few do not. If you don't drive and never travel by air -- something true of a lot of people who are poor, elderly, or in bad health -- then you may not have an unexpired government-issued photo ID that meets the sometimes narrow requirements of voter ID laws.
Getting an ID can be a significant expense and hassle. Even if the ID itself is free, it may require producing a birth certificate and sometimes a marriage license, which are typically not free. Obtaining one of those documents can in turn require producing a photo ID. It's possible to get past this Catch-22, but again it's a hassle especially if you don't need a photo ID for anything else. Then there's the matter of getting to the office that issues the ID when that office is open. In Sauk City Wisconsin, for example, the ID office open only on the fifth Wednesday of the month. (Take a look at a calendar and see how many months have five Wednesdays.)
The net result is that voter ID requirements end up blocking thousands of times as many valid ballots as invalid ones. They harm the integrity of the elections vastly more than they help.
If you think this is an exaggeration, compare the percentages of fraudulent votes cited by the Brennan Center against the percentage of people without IDs according to a report in today's Philadelphia Inquirer, among citizens of that city who have voted at least once in the last four years, more than 15% -- that's more than 136,000 Philadelphians -- do not have a state-issued photo ID. Among those age 18-24 it's more than 20%. For the elderly 80 and over it's more than 27%. (Some of those without state-issue IDs may have alternatives such as federal passports, but the great majority do not.) A more recent report by the Brennan Center (pdf) concludes that
Voter ID laws will make it harder for hundreds of thousands of poor Americans to vote. They place a serious burden on a core constitutional right that should be universally available to every American citizen.
This November, restrictive voter ID states will provide 127 electoral votes -— nearly half of the 270 needed to win the presidency. Therefore, the ability of eligible citizens without photo ID to obtain one could have a major influence on the outcome of the 2012 election.
So why do legislatures pass voter ID laws? Partly it may be a sincere if misguided effort to reduce fraud, but it's hard not to suspect that the reason is very often cold-blooded politics.
For more, see this article from The Washington Post.