The American Civil Liberties Union (search) said Tuesday that several states are using unreliable procedures to remove felons from voter registration rolls, possibly disenfranchising legitimate voters.

In a study of 15 states, the ACLU found that none specified the legal criteria for assuring that someone being purged from voter roles actually had a felony conviction. It cited one case in which Georgia denied a man's right to vote because his son, who had the same name, was convicted of a felony.

Of those 15 states, only four — Georgia, New York, Louisiana and Virginia — required election officials by law to notify people who were going to be purged from lists. The other states had a mix of procedures that could result in someone being wrongly taken off voter roles without the chance to object, the report said.

The ACLU said the states it picked for its survey represent the variety of ways felon voting is handled. Only Maine and Vermont allow all felons to vote. The other 48 states don't allow felons to vote while they are serving prison terms.

Thirty-five of those states also deny voting rights to felons on parole, and 31 include felons on probation. Seven states permanently bar felons from voting but have procedures for applying to regain voting rights, the report said.

Some 5 million citizens in those 48 states, including 1.5 million black men, have lost their right to vote because of felony convictions, the report said.

The 36-page report studied Arizona, California, Georgia, Illinois, Iowa, Louisiana, Maryland, Nevada, New Mexico, New York, Ohio, Pennsylvania, South Dakota, Texas and Virginia.