MILLIONS OF Americans have lost the right to vote, at least temporarily -- a denial of an essential element of citizenship. Yet there's no great outcry, because they are prisoners or ex-convicts. Human rights organizations that struggle to restore them to the voting rolls are performing a great service by refusing to accept the marginalization implied by loss of suffrage.

Practices vary around the country, with two states -- Maine and Vermont -- allowing prisoners to vote while they are serving time. In Massachusetts, where prisoners had been able to vote since the 1970s, voters passed a constitutional amendment in 2000 to keep people in prison from casting ballots. Seven states -- Alabama, Florida, Iowa, Kentucky, Nebraska, Mississippi, and Virginia -- bar people convicted of serious offenses from voting for life.

Any restriction on voting would seem to be a violation of the 14th Amendment to the Constitution, under which every American is guaranteed equal protection under the law. The amendment, however, provides a loophole that allows states to restrict voting "for participation in rebellion, or other crime."

In 1870, two years after the 14th Amendment was ratified, fewer than 33,000 people were in state and federal prisons. In mid-2003, in the latest count by the Justice Department, 1.458 million people were incarcerated. An article in the American Sociological Review estimates that at the end of 2000, 4.68 million people were being denied the vote as a result of a criminal record. What had been a quirk of law has become a major barrier to the political process.

A disproportionate number of disfranchised are black -- 1.8 million, the article said. This raises civil rights issues, which the Supreme Court has barely addressed.

In Florida, the loss of voting rights by 827,207 people -- 256,392 of them black -- likely made a difference in George Bush's contested victory over Al Gore in 2000. This year, most of these people remain off the rolls, but the Brennan Center for Justice in New York succeeded in discouraging Florida officials from using flawed lists to purge voters.

The prohibition against voting offers a perennial incentive to electoral mischief. In Ohio, local registrars were telling former prisoners that they could not vote, even though under law they were free to do so once they were released. Despite a settlement reached with the Prison Reform Advocacy Center last month, the state has reneged on an agreement to provide accurate information.

In Massachusetts, the Correction Department is informing inmates they cannot vote, but it has no plans to remind them that they can, and ought to, after release. The department should include this information in its prerelease program. Without this reminder, the in-prison ban could become a lifelong disincentive. Offenders who pay their debt to society should be restored to active citizenship.

Civil liberties groups are trying to change the Florida Constitution to end the ban there, but disenfranchisement is ingrained throughout the country, and a federal amendment is needed. Representative Jesse L. Jackson Jr., Democrat of Illinois, has filed an amendment to specify that everyone in the country 18 or over has the right to vote. The bias against convicts is so strong, however, that it might have a better chance of passing if it excluded felons still serving their sentences.

Restoring the vote to former prisoners would demonstrate that American democracy is secure enough to reach out to those traditionally excluded from the privileges and power that flow from participation in the electoral process.