What exactly are sanctuary cities? The problem with using a term that few can define

This week President Donald Trump tweeted that "Americans overwhelmingly oppose sanctuary cities," citing a poll published on Tuesday by The Hill.
According to the poll, a whopping 80 percent of respondents agreed that "cities that arrest illegal immigrants for crimes should be required to turn them over to immigration authorities." But that statement is based on a faulty premise, since it's usually counties —not cities— that can choose whether to turn over "deportable" immigrants to Immigration and Customs Enforcement (ICE) agents for deportation.
The poll's analysis —and Trump's tweet— illustrate a common misconception about the phrase 'sanctuary city', an ambiguous term with no legal definition often used to describe places that aren't even cities, or to talk about cities with policies that help undocumented immigrants but are not related to handing alleged criminals over to ICE.
During a recent two-day visit to the border, even the Homeland Security secretary, John Kelly, admitted that he doesn't know what sanctuary cities are: "I don't have a clue," he said when asked to define them.
While there are certainly some cities like Chicago that have publicly embraced the term, and established local policies to protect undocumented immigrants, cities are usually not involved in responding to ICE requests to hand over criminal immigrants for deportation. (In the case of Chicago, that decision falls upon the Cook County Sheriff's Office.)
In fact, a widely-cited list of nearly 300 places in the United States with sanctuary policies —compiled by the Center for Immigration Studies (CIS), which favors curbing immigration— is mostly made up of counties.
"I agree that it's not just sanctuary cities," said Jessica Vaughan, the director of policy studies at CIS who regularly updates the list. "I try to always say 'sanctuary' or 'sanctuary jurisdiction'. Some are states."
So why do Trump, the media and immigration advocates focus on sanctuary cities?
It may have to do with the case of San Francisco, which is one of the few places in the United States that is both a city and a county.
It was there that a woman named Kate Steinle was killed in July 2015 by an undocumented immigrant who had been previously deported five times. The San Francisco Sheriff's Office had ignored a detainer sent by ICE before the murder took place, which requested the jail to keep the suspect, Francisco Sánchez, under custody until he could be picked up and deported.
The Steinle murder brought the first big peak in the public's interest for sanctuary cities, according to Google Trends data. In fact, the tragic event inspired Vaughan, the expert at CIS, to start documenting sanctuary policies in other places across the country.
"When the Steinle case happened, all of a sudden everyone was interested in sanctuary policies, so I decided to drop something else I was working on to get it out, so more people would pay attention," she told Univision.
Since Steinle's murder, there has been a sustained focus on cities with sanctuary policies when discussing cooperation between ICE and local jurisdictions. But it's generally counties that are in charge of local jails around the country, and it's up to them to decide whether to hold immigrants temporarily while immigration agents come pick them up.
In fact, out of the 20 jails that received the most detainer requests from ICE in the past 15 years, only Rikers Island in New York was handled by a city agency, according to data gathered by the Transactional Records Access Clearinghouse at Syracuse University. Of the rest, four were state prisons and 15 were handled by counties.
"The jail-to-deportation pipeline is mostly grounded at the county level, where the civil immigration and criminal legal systems have become increasingly intertwined," says a recent study of sanctuary jurisdictions published by the Immigrant Legal Resource Center (ILRC), which points out that it specifically does not focus on city-level sanctuary policies.
The immigration expert Lena Graber, who co-authored the report, told Univision News that she finds the term 'sanctuary city' misleading. "It's a big misnomer, because jails are often managed at a county level, and ICE is heavily involved in county jails," she said.
So what are sanctuary cities?
Although the term doesn't have a clear legal definition, many of the self-described sanctuary cities in the United States don't allow police officers or city employees to ask residents about their immigration status. Others also prohibit the use of city funds, personnel or resources to assist immigration agents during deportation proceedings. Some have even set up funds to help immigrants with court fees.
Several experts told Univision News that these cities generally act within legal limits, although Trump and other Republican leaders have accused them of violating federal immigration laws.
Trump's executive order specifically defines sanctuary jurisdictions as places that "willfully refuse to comply with 8 U.S.C. 1373", a section of the Immigration and Naturalization Act that prohibits cities, counties and states from creating policies that restrict the sharing of "information regarding an individual's immigration status" with the federal government.
This definition further complicates things, since many so-called sanctuary policies (including the one cited in the poll tweeted by Trump) have nothing to do with sharing information with ICE about someone's immigration status.
"Part of the trouble with defining a sanctuary jurisdiction is that the policies really vary," said Philip E. Wolgin, an immigration policy expert at the Center for American Progress. Usually people think of places that deny ICE requests, he said, "but (the federal law cited in the Trump order) doesn’t mention that, and some courts have ruled that without probable cause or warrant you can’t hold someone; that it’s not constitutional".
'A big step in the right direction'
When the Homeland Security secretary discussed what would happen to sanctuary policies during his recent visit to the border, he promised to "make no draconian moves until I fully understand what a given locale might be doing or not doing."
But he also expressed shock at the fact that any jurisdiction would deny cooperation with immigration agents who seeked to deport criminals.
"It’s inconceivable to me that people who are sworn to protect their communities would not want someone —anyone— to remove criminals from their communities and send them somewhere else," Kelly said. "I’m stunned when people say, 'Well, we’re not going to cooperate with you even in the event of convicted criminals.' "
A reply to Kelly came from San Diego County sheriff Bill Gore, who explained that his county could not legally comply with ICE detention requests without probable cause.
"The best outcome is for ICE to take custody of people in our facilities, but recognize that they can’t be everywhere in California", Gore told the secretary. "What could help us is if we can get some type of warrant or court order to hold them. That would be a big step in the right direction."