In Congress and about a dozen states, recent debates over proposals to require photo identification at the polls have divided along partisan lines. Republicans generally support ID requirements and Democrats oppose them.

But both parties need to move beyond political posturing and empty rhetoric. Voter fraud is wrong. At the same time, however, advocates have yet to show that ID laws solve more problems than they create.

Photo ID requirements will reduce participation by legitimate voters. While more research is needed, one study by the Task Force on the Federal Election System showed that 6 percent to 10 percent of the existing American electorate lacks any form of state ID.

According to the AARP’s Georgia chapter, about 36 percent of Georgians over age 75 do not have a driver’s license. A 1994 Justice Department study found that blacks in Louisiana were four to five times less likely than whites to have photo IDs. In 2004, South Dakota voters in predominantly American Indian counties were two to eight times more likely to fail to bring ID to the polls than other voters.

Photo ID advocates downplay access concerns by arguing that responsible voters who bring an ID to the polls have nothing to fear and that IDs are commonly required to board airplanes, use credit cards and buy alcohol.

But while ID supporters explain how a person can protect his or her individual right to vote, they fail to address the structural impact of ID requirements.

As with recent abuses of the redistricting process, self-interested politicians can use ID laws to manipulate election results by disadvantaging political groups whose members are less likely to bring ID to the polls. Any rule that reduces participation by even 1 percent of legitimate voters can determine a close election.

Also, voting is different than boarding an airplane, using a credit card or buying alcohol. Airports and businesses demand IDs exclusively to further goals such as security and protecting minors. In contrast, some politicians benefit from ID requirements that reduce turnout in communities likely to vote against them. An individual air traveler or credit card user is inconvenienced when she forgets her ID, but with voting the harm extends past an absent-minded voter and impinges upon her political allies and a democracy that fails to reflect the will of the people.

Further, because ID proponents don’t provide facts about the magnitude of fraud, they prevent us from truly assessing whether the benefits of excluding fraudulent voters outweigh the costs of excluding legitimate voters. Photo ID advocates seek support by telling a few anecdotes about fraud, some of which an ID law would not prevent, such as double voting in different states, voting by ineligible felons, or ballot-box stuffing by election workers.

Photo ID supporters fail to produce tangible data or studies that establish or estimate the percentage of fraudulent votes cast. If only 0.01 percent of votes are fraudulent, for example, adopting an ID requirement that reduces legitimate voter turnout by 5 percent hurts democracy. If their arguments are going to be persuasive, photo ID advocates need to produce better facts that, at the very least, establish that more fraudulent votes will be deterred than legitimate votes.

Photo ID supporters need to address other practical issues as well. How will state officials prevent poll workers from enforcing the law selectively? New York City doesn’t even have an ID requirement, but a recent study showed that poll workers improperly asked one in six Asian American voters for ID. Also, what accommodations ensure that fewer legitimate voters are excluded? South Dakota, for example, allows voters without ID to sign an affidavit verifying their identity.

Finally, anti-fraud advocates should not burden voters without also clamping down on election administrators, who generally have greater opportunities to willfully or recklessly distort election results.

Laws should require regular and unannounced independent audits of polling places, county election boards, secretaries of state offices and private companies that provide voting machines and purge voter rolls. Unlike photo ID requirements, these anti-fraud measures pose little risk of discouraging legitimate voter participation and skewing election outcomes.

So far, politicians in both parties have debated the ID issue using shallow sound bites. We should demand better statistics about the magnitude of voter fraud and the extent to which ID requirements would reduce legitimate voter turnout. Based on those facts, we can determine whether the benefits of ID laws outweigh the costs.

Spencer Overton teaches at The George Washington University Law School and is currently writing a book on voting rights scheduled to be published by W.W. Norton in spring 2006.