Where are New Jersey's so-called "sanctuary cities?" Our own David Matthau is exploring the policies in New Jersey around them for an upcoming story, so we figured we'd take a look.

The problem: It's sort of a loaded question.

"Sanctuary city" is a nebulous term — broadly meaning any seen as willing to shelter people in the country illegally from federal immigration law. But there's no standard criteria.

Some mean it to refer to cities that bar police from questioning people solely about their immigration status. Others use the term to refer to cities that don't honor U.S. Immigration and Customs Enforcement requests to keep people in custody after they'd otherwise be released for local charges.

So rarely are two list of "sanctuary cities" identical. But whatever they are, Gov. Chris Christie says they should be defunded.

A 2007 order by the state Attorney General lays out the circumstances under which New Jersey law enforcement should investigate immigration status. After an individual has been arrested for a serious violation of state criminal law, immigration status becomes an issue — because it's relevant to the individual's ties to the community and the likelihood he or she will appear in court, the AG wrote.

And when the state has reason to believe someone arrested may be in the country illegally, federal officials should be informed, according to the AG.

But strong relations with immigrant communities are also important to enforcing the law, the AG wrote. So law enforcement can't ask about the immigration statuses of witnesses or victims without "good cause"

The ACLU of New Jersey notes both Newark and Princeton have policies of declining at least some detainer requests. Burlington and Union Counties don't honor ICE detainers effective in August of last year. Ocean and Middlesex Counties only honor some, requiring probable cause or a warrant to honor an ICE detainer request.

Last year, the ACLU sent letters to all New Jersey County jails urging them to decline requests "because they erode trust between local law enforcement and immigrant communities, jeopardize public safety, and pose significant constitutional concerns," according to the group.

For our own map below, we used the often-cited list maintained by Steve Salvi of the Ohio Jobs & Justice PAC. He describes sanctuary cities as ones where municipal employees are told "not to notify the federal government of the presence of illegal aliens living in their communities." That includes cities with on-the-books policies of various types as well as informal ones.

Also included are population figures as listed in five-year estimates by the U.S. Census' American Community Survey. Foreign-born population estimates are listed as well, though those are not specific to people in the country illegally — reliable figures on the undocumented are hard to come by.

Of note: Fort Lee had been on the PAC's list, though Mayor Mark Sokolich told NJ.com it disputes the designation, and its lawyers have sent a letter demanding it be taken off. The PAC lists Fort Lee's status as under review. "Fort Lee is committed to following the law," he said.

Hightstown is on the list, but its mayor reportedly says it shouldn't be. NJ.com quotes Mayor Larry Quattrone saying that's a misunderstanding of borough policy, and "If you get stopped for anything, (police) will check your status. If you have wants or warrants against you, whether you're a U.S. citizen, Latino, Greek or Italian, your status will be checked and if there's any problem, you will be turned over."

So take the map above, based on the Ohio PAC's list, with a grain of salt.