New York City, which has spent years bragging about how little it cooperates with immigration enforcement, has produced another entry for the files. Homeland Security put out a statement this week confirming an ICE detainer is now lodged against a violent illegal alien following an attack. You can read the original report here at RedState.

A detainer is a simple thing. It's a request that local jailers hold a person for up to 48 hours so ICE can come pick him up instead of watching him walk out the door and disappear. In most of the country that's routine paperwork. In New York City it's a philosophical crisis, because the city's sanctuary rules bar cooperation with ICE in most cases, detainers included.

Here's how the dance goes in a sanctuary city. An illegal alien commits a crime. Local cops arrest him. The jail has him in a cell, physically in custody, and ICE knows exactly where he is. Then the sanctuary policy kicks in, the jail releases him anyway, and ICE has to go hunt him down in the neighborhood later, which is harder, more dangerous, and more expensive for everybody involved. New York chose that system. So did a lot of cities.

The detainer in this case at least means the federal government is now formally on record wanting this man turned over. Whether the city honors it is a separate question, and past performance is not encouraging. New York has released people with detainers over and over, some of whom went on to hurt somebody else, at which point the same officials who made the release give a press conference expressing shock.

I've sat through enough of this from the other end of the pipeline to know how it plays out on the ground. When a smuggler or a runner gets loose in a county like mine, the cost doesn't show up in a press release. It shows up in a cut fence at mile marker 14, a water line torn up, a trough drained dry in August. Up in New York the costs look different, a woman assaulted on a subway platform, a store clerk hurt, a family getting the phone call, but the cause runs through the same pipe. Somebody decided the detainer didn't matter. Somebody decided the paperwork was optional.

ICE, for its part, keeps doing the job. The agency issues the detainers, tracks the cases, and when a sanctuary jurisdiction lets somebody go, they go find them again, often months later, often after a new victim has been created in the gap. Every one of those cases gets filed in the paperwork under politics, but out where the results land, it's just a preventable crime with a paper trail.

The scoreboard lately has been running the other direction, and that's worth saying. Border crossings are down hard, deportations are up, and the enforcement apparatus that spent four years being told to stand down is back to moving. Cases like this one in New York are the residue of the old arrangement: people who came in during the open-door years, settled into cities that promised not to turn them over, and found out the hard way that promises from politicians have a shelf life.

Watch what the city does with this detainer. If they honor it, that's the news. If they don't, the name will show up again, and next time there will be another statement from DHS and another round of officials acting surprised. I've seen this movie enough times to know how it ends, and so have you.