Image courtesy of Flickr user Still Burning , under a Creative Commons license.

Chicago doesn't cooperate. Neither does Philadelphia. Nor Baltimore, San Diego, Newark, Milwaukee, Miami-Dade or Denver.

One by one, these cities — soon to be joined by New York City — have passed resolutions or enacted new policies refusing to hand over immigrants detained by local police to federal officials for deportation. The strategy, gaining further momentum this year with a statewide law in Colorado, is one way local governments dismayed by a broken federal immigration system have found to undermine it.

At issue are what are called "immigration detainers." The federal government relies on local law enforcement agencies to help identify individuals for deportation. When local police come in contact with suspected immigrants (for reasons ranging from serious offenses to traffic violations), Immigration and Customs Enforcement often issue a detainer, asking local jails and prisons to hold them for 48 hours or more beyond their release to give the feds time to decide if they want to collect and deport them.

The federal government doesn't reimburse local agencies for resources they spend "holding" suspected immigrants on ICE's behalf. And civil rights advocates have repeatedly decried that the practice illegally imprisons people — sometimes for much longer than two days.

In many ways, cities with large and deeply rooted immigrant populations have interests here directly at odds with ICE. They have scarce resources to devote to public safety, which they believe are better spent addressing actual crime than federal immigration. (Recent ICE data suggest that only about one in 10 detention requests applies to people who've been convicted of a serious offense). Officials worry that the detention requests also undercut community policing, making neighborhoods less safe by discouraging victims in immigrant neighborhoods from reporting crime or working with police. Local communities, unlike ICE, are also left with the collateral damage of families fractured by deportation.

Immigration detainers also awkwardly stand at odds with the policies many cities are trying to deploy to accommodate immigrants, from granting them driver's licenses to ensuring they have access to city services.

A number of court rulings this year have declared that local agencies aren't required to accept detainer requests. And so more and more — here's a full list of dozens of cities and counties — are setting explicit policies to refuse them.

UPDATE: I'd be remiss not to point out that the District of Columbia refuses ICE detainer requests as a policy, too.