DEFINITION OF SANCTUARY CITY
There is no definitive definition of a ‘sanctuary city,’ per se.However, the U.S. Department of Justice (DOJ) operationally enforces a legal definition. Under Federal Law 8 U.S.C. Section1373, the DOJ defines sanctuary cites as a local government entity not reporting to federal authorities: ‘aliens in custody.
Federal Funding of America's Sanctury Cities by Barbara Espinosa on Scribd
(h/t Christopher Fromme)