SANTA ANA -- California voters will consider toughening the penalties on human trafficking in a November ballot initiative funded almost entirely by a former Facebook official and opposed -- somewhat surprisingly -- by some advocates who are trying to stop the exploitation.

If it's approved by voters, Proposition 35 would more than double sentences for human traffickers and impose a life sentence for the sex-trafficking of children. It also would require sex offenders to provide email addresses and other Internet identifiers to law enforcement.

Former Facebook Chief Privacy Officer Chris Kelly has contributed nearly 90 percent of the $2.2 million raised in favor of the initiative. He said his goal, in part, is to replicate a crime-fighting program used in New York that requires sex offenders to reveal their online identities to police.

"It requires them to disclose an electronic address, the same way they have to disclose a physical address," said Kelly, who lost a bid for state attorney general in 2010. "It will be used to fight the biggest scourges and the biggest traffickers."

The initiative also broadens the definition of human trafficking and raises the penalties for offenders.

It is endorsed by the state Democratic and Republican parties, a host of law enforcement agencies and police unions, anti-trafficking groups and numerous newspaper editorial boards. But the initiative also faces opposition -- perhaps unusually so -- from some of the advocates who work with victims of human trafficking in the state.

John Vanek, a retired police lieutenant from the San Jose Police Human Trafficking Task Force, said Proposition 35 might be well-intentioned but could discourage prosecutors from charging cases under the state's human trafficking laws. He said, for example, it could limit the information they can use in court.

Vanek said he also opposes setting different penalties for sex and labor trafficking, and argues that a jury -- not voters -- should decide the severity of a case.

The Los Angeles-based Coalition to Abolish Slavery & Trafficking, which works directly with trafficking victims, said in a statement that the organization welcomed the attention the initiative had brought to the issue but worries that aspects of it could lead to unintended consequences. For example, it could decrease the amount of money available to survivors through civil remedies because of the increase in criminal fines.

When voters begin studying the initiative, the opposition cited in the ballot pamphlets will be sex workers who fear that broadening the definition of human trafficking will render them victims under the law.

Maxine Doogan, president of the Erotic Service Providers Legal, Education and Research Project, said she is worried that the relatives of sex workers could be criminally charged as traffickers for receiving money or support from their family members' work.

Human Trafficking-Glance
What it would do: Increase the penalties for human trafficking, especially the sex trafficking of children, and require training for law enforcement on handling trafficking complaints. Expand the definition of human trafficking and require sex offenders to provide their email addresses and Internet identifiers to law enforcement.
Support: Former Facebook Chief Privacy Officer Chris Kelly is the main proponent behind the initiative, along with the anti-human trafficking nonprofit California Against Slavery. The measure is endorsed by the state's Democratic and Republican parties and numerous law enforcement groups and victims' advocates.
Oppose: Some trafficking victims' advocates are opposed. So are sex workers represented by the Erotic Service Providers Legal, Education and Research Project.
Campaign donations: Groups supporting the initiative have raised more than $2.2 million, with most coming from Kelly. No campaign finance information has been filed with the state by groups opposed to the initiative.