Proposition 83 -- which would prohibit convicted sex offenders from living within 2,000 feet of a school or a park in California -- was approved by 70 percent of those who voted on it Tuesday, the Los Angeles Times reported.
Wednesday's order by U.S. District Judge Susan Illston in San Francisco means a key portion of the proposition may not be enforced while its constitutionality is being considered by the courts. A hearing was scheduled for later this month in the challenge to the initiative, brought Wednesday by attorneys for an anonymous plaintiff.
The lawyers argued that the initiative constitutes a new penalty on ex-convicts years after they have been already punished for their crimes. The plaintiffs also argue that the measure is unconstitutional because it would force offenders from their homes without notice.
Illston said the challenge probably would prevail when it is heard in court.
Gov. Arnold Schwarzenegger's legal affairs secretary told the Times the administration would fight the lawsuit.