“Sanctuary cities” — municipalities that refuse to cooperate with the federal government on immigration policy — have existed in the United States for more than thirty-five years. Over the last decade, various legislative efforts have been made to crack down on noncompliant jurisdictions. Still, by one count, at least 276 sanctuary cities exist in 32 states and the District of Columbia.

The debate over sanctuary cities was revived on July 1 when illegal immigrant Juan Francisco Lopez-Sanchez allegedly shot and killed 32-year-old Kate Steinle, who was walking along the San Francisco waterfront with her father and a friend.