The federal Immigration and Customs Enforcement promotes its Secure Communities program known as a way to protect communities.
San Francisco Supervisor John Avalos calls it a dragnet that snags more than suspected criminals.
"Often victims and witnesses of crimes who are undocumented get caught up in the criminal justice system and their finger prints get sent to the federal government and ice sends a letter to our sheriff and asks the sheriff to hold them," Avalos said.
The supervisor says fear of deportation makes people afraid to report crimes. Sonia Cauich had the courage to call 911 about domestic abuse last year, but tells of an Secure Communities nightmare.
"When the police arrived they arrested me and took me to 950 Bryant where I spent three days," she said.
That's the kind of case that has prompted Avalos to suggest the city and county no longer cooperate with ICE. He has the backing of the current sheriff and the district attorney, but Mayor Ed Lee wants exception for serious offenders which is basically current city policy.
"We have someone who comes into our jurisdiction that might have a criminal record of conviction of a violent offense, or child molestation, or sexual trafficking, I think we ought to have a second look at the individual," Lee said.
The head of the San Francisco Police Officers Association agrees.
"You can't tie the hands of law enforcement when it comes to violent offenders regardless of their immigration status," Martin Halloran said.
The Avalos proposal to snub federal requests originally had the support of the majority of the board, but with pressure from the mayor and police chief, a flurry of last minute amendments was introduced Tuesday afternoon and the vote put off until next week.