I heard the story about police in Washington attaching a GPS transmitter to the car of a man suspected of killing his daughter, then tracking him to where he had buried her remains. Here's Wired's take on the story, which raises some pretty interesting issues.

Satellite positioning relies on signals from a constellation of 24 U.S. military satellites to pinpoint one's exact position on the planet. The Jackson case involved a GPS receiver combined with a digital cellular transmitter.

On Tuesday, Jackson's lawyer argued that Spokane County sheriff's deputies obtained a court order to wire the device to his car on the slimmest of premises: if guilty, Jackson might return to the crime scene.

And he did. And they caught him. And they found the little girl's remains.

Now the guy's lawyer is trying to get the evidence thrown out of court. The police are arguing that the tracker is only providing them information that a trailing police car or a person on the street seeing the car go by could phone in to the police...in other words, it's publicly available information.

There's something intrusive about the police actually affixing a device to your property, but overall I think they have the stronger argument here. And apparently, according to the NPR story, similiar cases of police using electronic tracking devices (but not GPS) have been upheld by the courts.

So I'm fine with it, as long as it still requires a warrant.