No candy, no decorations, no porch light and definitely no trick-or-treaters.

On Halloween night, these things spell parole violation for some registered sex offenders in California, thanks to “Operation Boo,” a special one-night-only set of rules enforced by parole that includes a dawn-to-dusk curfew and prohibition against handing out candy.

But in San Francisco, because 67 of the 72 registered sex offenders on parole are homeless, Operation Boo calls in a different set of rules, according to Fred Bridgewater, the Region II assistant public information officer for the California Division of Adult Parole.

Transient offenders must report to the Northern California Service League in SoMA from 5 to 10 p.m. on Halloween, after which the agency expects most children will be back at home. Year round, they must wear GPS tracking devices and report to their parole agents weekly to update them on their whereabouts.

In addition to those on parole, there are 58 registered sex offenders in the Mission District’s 94110 zip code who have completed their parole terms and therefore are not covered by Operation Boo.

Thirty-eight of those offenders were convicted of sexual crimes with children 15 and younger, according to the Megan’s Law website.

Though all sex offenders must register their addresses at least once a year for life, only offenders considered high risk are subject to school-related residency restrictions once they have completed their three-year parole term. Those convicted of child molestation or child annoyance cannot live within a half a mile of a school, and sexually violent predators cannot live within a quarter of a mile.

Bridgewater said that although Operation Boo has been in existence for 17 years, “there are no historical problems that gave rise to this operation.” Sergeant Wilfred Williams, public information officer for the San Francisco Police Department, said he does not remember any major incidents involving sex offenders and children on Halloween during his 17-year tenure with the department.

The high number of transient parolees in San Francisco reflects the difficulty of paroled sex offenders complying with the 2006 Proposition 83 that prohibits them from living within 2,000 feet of a school or park, regardless of whether their offense involved children.

“When you apply that to the city and county of San Francisco, virtually the whole city is not compliant,” said Bridgewater. The number of transient sex offenders rose dramatically soon after the 2006 law was implemented, according to data from the California Sex Offender Management Board.

The difficulty for sex offenders convicted in San Francisco and paroled after Proposition 83 was passed is that they serve their parole terms in the county where they committed their crime unless they are granted a parole region transfer–which is seldom successful.

This has left San Francisco sex offenders with few options and an increasing number live in encampments, under bridges or in parks. Only San Diego is as difficult a city for sex offenders to find housing, Bridgewater said.

Two Bay Area civil rights attorneys are challenging the legality of the residency restrictions imposed by Proposition 83. They are representing four parolees—including one who lives in San Francisco—in cases that will be argued in front of the California Supreme Court on Nov. 3.

“We want the court to rule that this law violates the state constitution and shouldn’t be enforced,” said Ernest Galvan, one of the attorneys.

The 17-member California Sex Offender Management Board—representing both state and non-governmental agencies—issued a report in January 2009 recommending “that the California State Legislature, Governor, and local governments reconsider residency restrictions to create an offender housing and supervision solution that balances three essential concerns,” including public safety, fair share and local control.

Full disclosure: Vanessa Carr worked as a paralegal in Ernest Galvan’s law firm from 2005-2006.