KANSAS CITY, Mo. -- A federal judge has been asked to bar the state and its 114 counties from releasing their lists of convicted sexual offenders.

U.S. District Judge Nanette K. Laughrey already has granted an injunction barring the release of the names of three Kansas City-area plaintiffs. On Thursday, she granted class-action status to six other men challenging the law, meaning those six now potentially represent more than 17,000 Missouri residents required to register.

On Friday, attorney Arthur A. Benson II, who represents the plaintiffs, asked Laughrey to extend the preliminary injunction to the entire class -- essentially gutting Missouri's "Megan's Law."

The law requires convicted sex offenders to register with authorities. Registration lists, which are supposed to include names and current addresses of those convicted of certain sexual offenses, can be obtained at sheriff's offices.

Benson said the law makes no distinction between a serial rapist and someone who had underage sex, and can stigmatize those who aren't dangerous.

A spokesman for Missouri Attorney General Jay Nixon, who is named as a defendant in the lawsuit, declined to comment on the developments. Nixon has asked to be dismissed from the suit because the attorney general plays no role in compiling or disseminating the sexual offender list.

The developments stem from an amendment to Missouri's Megan's Law that took effect in August. It required all sex offenders to register with their sheriff's office. Previously, the law only required offenders to register when they moved into a county.