APPLETON, Wis. -

Appleton police are using scanner technology to keep convicted criminals out of some of the city's most popular bars, but critics are raising privacy concerns.

Authorities claim checking bar patrons with an ID scanner is making the community safer.

Appleton police officer Adam Nagel said the program originated as a way to check for fake IDs. But Nagel said police are not only deterring underage drinkers, they're preventing convicted criminals from causing problems downtown.

Several Appleton bar owners approve of the scanners' use. But critics say it amounts to an invasion of privacy.

Executive Director Chris Ahmuty of the American Civil Liberties Union of Wisconsin said "there's no distinguishing between who gets targeted."

Gannett Wisconsin Media reports police agencies from Milwaukee to Wausau are interested in following Appleton's lead.