"If history is any guide, there could be a great deal of litigation as a result of this measure," said Jack Pitney, Professor of Government at Claremont McKenna College. More than half of all ballot initiatives passed by Californians are subject to legal challenges.

At the core of the proposition are residency restrictions prohibiting sexual offenders from living within 2,000 feet of schools, parks or playgrounds; increased sentences and parole terms; and lifetime tracking of sexual offenders using a global positioning system or GPS ankle bracelet.

With 30 percent of the vote counted, the proposition was ahead with 71 percent of the vote. Going into the elections, 76 percent of the public supported Prop. 83, according to an August Field poll.

"The measure was solid as mom and apple pie," said Marc Klaas of the Klaas Kids Foundation, a child safety group.

Despite its success, the laundry list of potential problems is long. Organizations and representatives like Senator Dean Florez from Kern County worry that the strict residency restrictions will drive sex offenders out of cities making rural areas, "a dumping ground for sexual predators."

In California, paroled sex offenders considered "high risk" are already being monitored in pilot programs that use GPS bracelets.

Prop. 83 will extend GPS tracking to all registered sex offenders. Those costs and the price of increased incarceration will reach $200 million annually over the next decade, according to the Legislative Analyst's Office.

Nevertheless, virtually every politician endorsed the measure, which was sponsored by husband and wife State Senator George Runner and Assemblywoman Sharon Runner of Lancaster. Governor Schwarzenegger co-sponsored the initiative and his opponent, Phil Angelides supported it.

"From a political standpoint, opposing this measure is all pain and no gain," said Pitney.

Even the measure’s staunchest supporters, however, acknowledged potential problems. "I believe there are some fundamental flaws in Proposition 83," Klaas said.

The residency restrictions of the law contain potential constitutional conflicts including cruel and unusual punishment and a violation of the 14th Amendment’s equal protection clause.

"Drafting of propositions is notoriously weak,” said Bruce Cain, director of UC Berkeley’s Institute for Governmental Studies. “Court is the only place to sort these things out."