San Francisco is poised to become the first county in the country to stop detaining immigrants on behalf of the federal government. An ordinance proposed by Supervisor John Avalos would make it illegal for local law enforcement to detain people only on the basis of their immigration status, The San Francisco Chronicle reports. The proposal heads to a committee vote on Thursday, where it is expected to pass to consideration by the full Board of Supervisors, enough of whom reportedly support the idea to withstand a veto from the mayor. The city and county of San Francisco are governed locally by a Board of Supervisors rather than a City Council. "The legislation is about due process against the arbitrary loss of liberty," Avalos told the Chronicle.