Electronic voting has made great strides in reliability, but it has a long way to go. When reformers push for greater safeguards, they often argue that future elections could produce the wrong result because of a computer glitch or be stolen through malicious software. That's being too nice.

    There have already been elections in which it is impossible to be certain that the right candidate was declared the winner. Here are three such races. It is not just remarkable that these elections were run so badly, but also that the flaws are still common - and could easily create havoc in this fall's voting.

    1. The 2002 Georgia Senate and Governor Races - Senator Max Cleland, who lost three limbs in Vietnam, was defeated for re-election and Gov. Roy Barnes, a Democrat, was unseated. Polls had suggested that both men would win.

    The votes were cast on Diebold A.T.M.-style machines. A whistle-blower who helped prepare the machines reported that secret "patches" - software intended to fix glitches - were installed late in the process without being certified by the state, as the law required.

    The unexpected outcomes were likely because of heavy turnout by rural whites, prompted by a Confederate flag dispute, not faulty voting machines. Still, skeptics wonder if the patches contained malicious software that changed votes. Because the Diebold machines did not produce paper records, there is no way to put those doubts to rest.

    Lesson: Electronic voting makes large-scale vote theft easy. A patch slipped onto voting machines or centralized vote tabulators can change an election's outcome. Every piece of software must be scrutinized by neutral experts. If there is not enough time, election officials need a backup plan, such as conducting voting entirely on paper ballots.

    2. The 2006 Congressional Race in Florida's 13th District - The machines said that Republican Vern Buchanan defeated Democrat Christine Jennings by 369 votes. But in Sarasota County, a Democratic area, up to 18,000 ballots, about 13 percent of the total cast, did not record a vote for Congress. That is extraordinarily high; in Republican Manatee County, only 2 percent of ballots didn't contain a vote for Congress.

    Sarasota's low vote may have been because of a bad ballot design, which made the Buchanan-Jennings race hard to find. But the Jennings campaign said it received hundreds of complaints that the machines would not accept a vote for Ms. Jennings, or recorded a vote for her as a vote for Mr. Buchanan.

    Did Ms. Jennings lose a seat in Congress because of a glitch? Could there have been sabotage? We'll never know, because there are no paper records.

    Lesson: Electronic voting machines must produce a voter-verifiable paper trail for each vote so voters can see that their choices register properly. In a disputed election, the paper, not the machine tallies, should decide who wins.

    More than half the states require votes to be recorded on paper, but many still don't. These include battleground states like Virginia.

    3. Alabama's 2002 Race for Governor - Former Gov. Don Siegelman has been in the news because it appears that federal prosecutors may have put him in prison for political reasons. The controversy has brought attention to the odd way he lost the governorship.

    Mr. Siegelman went to sleep on election night thinking he had won. But overnight, Republican Baldwin County reported that a glitch had given Mr. Siegelman, a Democrat, about 6,000 extra votes. When they were subtracted, Republican Rob Riley won by roughly 3,000 votes.

    James Gundlach, a professor at Auburn University, crunched the numbers and concluded that Mr. Siegelman lost because of "electronic ballot stuffing," possibly by an operative who accessed the computers and "edited" the results, though others dispute his analysis.

    Baldwin County used paper ballots that were then read by an optical scan machine. Mr. Siegelman says local officials gave him permission to count the paper ballots by hand, but the attorney general threatened to arrest anyone who did. No count was done.

    Lesson: Paper ballots alone are not enough. There must be strong audit laws that mandate comprehensive hand recounts when an election is close.

    After the 2000 election debacle, Americans demanded a better system of voting. What we have gotten is new technology with different flaws. If the presidential race is close, this year's "hanging chad" could be a questionable result on electronic voting machines that cannot be adequately investigated.