The rapid spread of cellphones with GPS technology has allowed police to track suspects with unprecedented precision — even as they commit crimes. But the legal fight is only now heating up, with prosecutors and privacy activists sparring over rules governing the use of powerful new investigative tools.Here's the opinion (pdf), which came out of the 6th Court of Appeals, not the 5th, which governs Texas, though the GPS tracking happened here. The gist is that GPS tracking of a cell phone is simply gathering information in the public domain akin to physically watching someone walk down the street. Though the US Supreme Court held in US v. Jones that a warrant is needed to place a tracking device on someone's car, the 6th Court of Appeals distinguished GPS in your phone from that case by claiming cell phone users "voluntarily" invite government tracking simply by owning a phone that emits such a signal:
The U.S. Court of Appeals for the 6th Circuit stirred the debate last week when it supported police use of a drug runner’s cellphone signals to locate him — and more than 1,000 pounds of marijuana — at a Texas rest stop. The court decided that the suspect “did not have a reasonable expectation of privacy” over location data from his cellphone and that police were free to collect it over several days, even without a search warrant.
the Government never had physical contact with Skinner’s cell phone; he obtained it, GPS technology and all, and could not object to its presence.Even before US v. Jones, Texas law required a court order for police to place a mobile tracking device on your vehicle. But Texas cops could conceivably track the GPS signal from your phone (Fort Worth PD recently purchased such a system) without one, since it's not something police installed but, according to the 6th Court, information you're "voluntarily" giving out in a public space. In light of this ruling, the 83rd Texas Legislature should amend that statute to require judicial oversight for GPS tracking as well.
Because authorities tracked a known number that was voluntarily used while traveling on public thoroughfares, Skinner did not have a reasonable expectation of privacy in the GPS data and location of his cell phone.