Looks like the cops, and law-abiding New Yorkers, just lost another one.

On Wednesday, a state judge in Brooklyn issued a ruling that limits the NYPD’s use of a powerful crime-fighting tool, called a Stingray, which can track the location of a criminal suspect’s cellphone.

The judge tossed the arrest of a murder suspect — yes, a murder suspect — and let him walk, though he allowed cops to re-arrest him on different grounds.

What drove that decision? Cops, the judge said, used the device without a warrant to track his location to his home based on his cellphone’s signals, and that intruded on the suspect’s “expectation of privacy.” The device, he says, “acts as an instrument of eavesdropping.”

True, this wasn’t the first such ruling. But why should cops need a warrant simply to locate someone by using cellphone signals traveling through free, public airspace — especially given that they don’t review the content of any of the calls?

Sure, police can try to get a warrant to track a cellphone location. But that could take time, possibly costing them a key chance to nab their suspect.

Critics claim that, absent limits on Stingray-like technologies and oversight, “we face the prospect of comprehensive police monitoring and tracking private, lawful activity.” And yes, technology like this needs to be regulated and monitored; clearly, it can be abused.

But if the devices are used properly, innocent bystanders whose data may inadvertently be collected have little to fear — because they haven’t done anything wrong. Criminals, on the other hand, should fear getting caught. If they don’t like it, they can avoid cellphones. Or not commit crimes.

Fact is, cops need these tools. And using the public airwaves to obtain the location of bad actors is a far cry from spying on anyone’s e-mail, texts or voice calls.

Tying cops’ hands yet again is just another victory for the lawless.