Last week’s tragic random killing of 32-year-old Katherine Steinle by an undocumented immigrant has raised a serious question. If San Francisco had not been a “sanctuary city” for undocumented immigrants, would Kathryn Steinle still be alive?

San Francisco is one of 200 “sanctuary cities” throughout the United States. Sanctuary cities are defined as those which provide a haven for undocumented immigrants, either by statute or by unofficial  (de facto) policy. Municipal governments in these cities refuse to cooperate with federal immigration authorities. Overall sanctuary policies vary, but in general such undocumented immigrants have access to the same basic services and protections as citizens and legal residents, such as emergency services, health care, library privileges, education, food banks, emergency shelters and public recreation facilities. Some sanctuary cities even issue identification cards to such persons.

The concept of sanctuary cities is in part a response to increasing urbanization. Today, more than 50% of the world population resides in cities. If current demographic trends continue, that figure will rise to more than 85% within the next thirty-five years. Sanctuary cities are seen by many as a way to create safe and even vibrant communities where new arrivals can more easily assimilate and become contributing members of society. Others consider them a hideout for criminals as well as a threat to national security.

Sanctuary cities in the U.S. date back to the 1970s. It was a period during which there was an influx of immigrants fleeing civil wars in Central America. In 1979, Los Angeles became the first municipality to institute sanctuary policies. Special Order 40 prohibited law enforcement officers from asking about an individual’s immigration status unless the person was a criminal suspect. It allowed undocumented immigrants who themselves were victims of theft or assault to report such incidents to police without fear of deportation.

Crimes committed by illegal immigrants is at the heart of the current debate over sanctuary cities. Katherine Steinle’s confessed killer, Francisco Sanchez, had an extensive rap sheet. However, except for an assault charge in the mid 1990s, none of Sanchez’ crimes were violent. In the wake of Steinle’s killing, San Francisco Mayor Edwin Lee emphasized that San Francisco’s “sanctuary policy” was “not intended to protect repeat, serious and violent felons.”

Research indicates that the vast majority of undocumented immigrants are no more likely to commit violent crimes than anyone else – and may even be less inclined to do so. Non-violent drug offenses are another matter. Some sources – among them, the right-leaning Washington Examiner – report that “illegal immigrants” account for nearly 75% of those imprisoned for drug possession. However, this is misleading. The data from the United States Sentencing Commission upon which that report was based gives the figure for non-citizens; it does not differentiate between resident aliens who are in the U.S. legally from undocumented immigrants.

That said, it should be noted that Sanchez had a long history of substance abuse and drug offenses. He admitted to being under the influence when he shot Katherine Steinle. Because of this singular act, the entire concept of sanctuary cities is being questioned. There is growing pressure from federal and state governments to end the practice.

Given the reality of increasing numbers of people fleeing poverty, violence, and the effects of climate change in Mexico and Central America, sanctuary cities are certain to become the subject of increasingly heated debate as we head into next year’s elections.

Post your comments and thoughts on whether sanctuary cities are good or bad.