Thousands of undocumented immigrants arrested in the city each year would no longer be turned over the feds under a law proposed Thursday by City Council Speaker Melissa Mark-Viverito. The bill would shield all immigrants who are picked up on low-level charges and are being sought by immigration authorities because they are in the U.S. illegally. That represents a major change from current policy, which is to honor most detention requests by the feds. In such cases, agents take the detainees into custody for possible deportation. Mark-Viverito’s proposal also calls for closing the office used by U.S. Immigration and Customs...