Herbert Lin, one of the authors of the report, told Wired.com that the method states use to develop their procedures often involves "a bunch of guys sitting around a table saying 'Let's try this' and 'Yeah that seems reasonable.'"
The federal Election Assistance Commission advises states not to leave final matching decisions to algorithms, and to have humans examine records that fail and contact voters to resolve discrepancies.
HAVA doesn't say what to do with applicants when matching issues can't be resolved. It says only that first-time voters who register by mail, rather than in person, and whose records can't be matched, must show ID at the poll.
Most states will register applicants who fail a match and let them cast a regular ballot after showing ID at the polls. But three states -- Iowa, Louisiana and South Dakota -- won't register applicants who fail. Iowa does, however, permit Election Day registration, which may allow a rejected applicant to reapply for registration at the poll and cast a regular ballot. Louisiana and South Dakota let the rejected applicants vote after showing ID at the poll but only on a provisional ballot, which may or may not be counted, depending on circumstances and state law. A survey of the 2004 general election showed that states varied in the percentage of provisional ballots that were cast and counted. Most states fell in the 30-70 percent range.
"Provisional ballots are really problem ballots; we don't want people to use them if there's a way not to," says Michael Slater, executive director of Project Vote, a voting integrity group.
Last week Florida, a battleground state, announced a new policy that voting groups say will likely disenfranchise numerous voters. A state law passed in 2005 initially prohibited applicants whose records didn't match from either being registered or voting. But after some 13,000 voters were blocked for bad matches in 2006, and more were blocked in 2007, the state was sued by several groups, forcing it to change its plan.
Beginning Sept. 8, new registration applicants who fail a HAVA match must mail a copy or bring a hard copy of their ID to an election office before Nov. 4 to show that the ID number on their registration application is correct. Officials plan to send a letter to such voters explaining what to do. Voters who forget or never receive instructions can cast a provisional ballot on Election Day, but it will be counted only if they bring or send a copy of their ID to an election office within 48 hours. ID presented at the poll will not be accepted, which could create confusion since Florida law already requires everyone to show ID at the polls.
Election experts say the policy places an unfair burden on voters who may fail a match through no fault of their own, especially since most states get huge spikes in registration applications just before registration deadlines, increasing the likelihood that harried clerks will make data-entry errors.
"Allowing voters to return within 48 hours is worrisome because, the truth is, a lot of them won't," says Tokaji. "Maybe, if it comes down to Florida deciding the presidency, God help them, they will return. But … the more complicated you make things, the more votes won't be counted."
Critics of the policy predict it will affect 10 to 20 percent of new registration applicants.