The fourth appellate district decision reverses the conviction of Hugo Godinez, a registered sex offender who was convicted of a misdemeanor for violating the county ordinance after he went to a company picnic at Mile Square Regional Park in Fountain Valley in 2011. Godinez had been convicted of misdemeanor sexual battery in 2010.

The county's restrictions on sex offenders, passed in 2011, were among the most aggressive in the state.

A number of cities within Orange County adopted versions of the law at the urging of the district attorney's office, and many of them also faced court challenges.

An Orange County Superior Court appeals panel overturned Godinez's conviction in 2012. In response, the Orange County Sheriff's Department stopped enforcing the law, and the Lake Forest City Council voted to repeal its ban.

The county appeals panel said the sex offender law appeared to be illegal and asked the 4th District Court of Appeal to hear the case.

"Godinez argues state law preempts the county ordinance and therefore his conviction is void. We agree," the appeals court ruling said.

The state Legislature has already enacted a "comprehensive statutory scheme regulating the daily life of sex offenders," and the Orange County law conflicts with it, the panel found.

Orange County's law allows sex offenders to go to parks with written permission from the county sheriff. The appeals court found that requirement amounts to a "de facto registration requirement" that conflicts with the state's existing sex offender registration requirements.

Representatives of the Orange County district attorney's office could not immediately be reached for comment.