The proposed law would require that juvenile suspects be convicted of a felony before San Francisco officials contact federal immigration authorities - unless the suspect is charged as an adult.

Currently, immigration authorities are contacted at the time of a felony arrest - a change implemented last year by Mayor Gavin Newsom after the city's sanctuary city policy made national headlines. Newsom's change angered many in the city's immigrant community.

Supporters of Supervisor David Campos' proposed amendment to the 1989 sanctuary city ordinance say most juveniles arrested on suspicion of a felony later see those charges dropped to a lesser offense in court. They also argue that youths should be treated differently than adults and make the case that police would gain greater trust if the threat of splitting up families is removed.

The legislation appears to have enough support to pass the Board of Supervisors, which may be able to override a mayoral veto should that be the case.

Detractors warn that if passed, the proposal could open the city up to legal challenges. It could also impact policies nationwide.

Angie Junck, an attorney who has been tracking sanctuary city policies for several years, said that what happens here is being closely watched. The city has one of the few written policies in the United States, and while it was once one of the most liberal when it came to handling undocumented juvenile immigrants, the change last year made it one of the toughest.

"This is a carefully drafted piece of legislation that in a very measured way strikes the balance between two extremes: the prior extreme of never reporting anybody to immigration authorities when laws were broken and the other extreme of the existing policy, which in a very reactionary way reports children the moment they are booked for something they may or may not have done," Campos said.

Evolving policy

San Francisco's sanctuary city ordinance, created in the late 1980s for refugees fleeing Central American civil wars, made headlines last year after The Chronicle reported that the city was shielding young felons from deportation. In one of the most high profile cases, Edwin Ramos, 22, who had been arrested for several felonies as a youth but never referred to immigration officials, was arrested and charged with the 2008 slayings of Tony Bologna and his two sons.

Newsom's new policy angered Latinos and immigrants, who said the change has cast too wide a net and led to racial profiling. Lawyers for youths who have been arrested cite cases where legal residents are referred to immigration officials, or where youths arrested for minor offenses are suddenly taken from their family.

One of the youths facing deportation is a 16-year-old Mission District resident who did not want his name used because his immigration case is pending. The teenager was arrested for felony graffiti, though a juvenile court judge considered the offense minor enough to warrant just six months of informal probation and some community service. The teenager has lived here since he was 7 and says San Francisco is the only home he knows. "I won't have no one to turn to - no shelter, no food," if he is deported, said the youth, whose father lives in San Francisco.

Junck, the attorney, argued that referring children for deportation can have terrible effects because youths who may have committed a minor offense often become trapped in a web of more serious crimes, including illegally re-entering the United States to reunite with their families.

"It becomes a maze they can never get out of," she said.

Legal questions await

However, even if Campos' legislation passes, it could face legal challenges.

Newsom's spokesman, Nathan Ballard, warned that if the city does "not follow state and federal law to the letter, our sanctuary city ordinance will not survive." Whether the current policy follows stated and federal law is in dispute.

Two lawsuits have already been filed regarding San Francisco's sanctuary city policy. In one, Bologna's surviving family members are accusing the city of negligence.

In the other, Charles Fonseca argues that the city's policy violates a state law that requires police to tell federal authorities whenever they arrest a suspected illegal immigrant for any of 14 specified drug crimes, including misdemeanor possession.

The lawsuit was thrown out once but was reinstated on appeal, and is still pending.

Supporters of Campos' legislation said its overarching aim shouldn't be sacrificed because of drug crimes that account for only a fraction of the offenses youths can be charged with.

Yet a draft report prepared by the Juvenile Probation Department earlier this year showed that the majority of undocumented youths in the juvenile probation system were there because of drug offenses. Over a four-year period, out of 252 cases involving undocumented youths, 180 were accused of drug offenses, the report said.

U.S. Attorney Joe Russoniello, a Republican appointee and vocal critic of the city's sanctuary policy, said in a statement that "legislating 'harboring' will provide no greater protection against federal criminal prosecution than any of their past suspect practices did."

E-mail the writers at mlagos@sfchronicle.com and jcote@sfchronicle.com

This article appeared on page A - 1 of the San Francisco Chronicle