The California State Assembly Wednesday voted to approve legislation that would prohibit state law enforcement personnel from obtaining location data from an individual's GPS-enabled mobile devices without a warrant.
The bill still requires approval by the State Senate and the signature of California Gov. Jerry Brown, who vetoed an earlier, broader version of the legislation last year.
The latest location privacy bill, sponsored by Democratic State Sen. Mark Leno, is one of the first of its kind in the country.
The bill, dubbed SB 1434, seeks to extend a U.S. Supreme Court ruling earlier this year requiring that warrants be obtained before law enforcement officials can attach GPS technology to a vehicle to track suspects in a crime, the Electronic Frontier Foundation noted in a blog post Wednesday.
"Location privacy scored a victory today when the California Assembly overwhelmingly passed [SB 1434]," EFF staff attorney Hanni Fakhoury noted in the blog post.
The EFF and American Civil Liberties Union (ACLU) are co-sponsors of the California legislation.
Leno's bill is designed to protect against warrantless tracking of an individual's whereabouts using information gathered from GPS-enabled smartphones and other mobile devices.
The legislation would mandate search warrants except in emergencies and certain narrow circumstances. The bill would also limit how long law enforcement personnel can track an individual even with a search warrant.
The Supreme Court made its landmark ruling in January in connection with the case of a man convicted on drug related charges based on evidence gathered by police using GPS technology attached by police to the suspect's car without first obtaining a warrant.
The Supreme Court, by a 9-0 vote, held that the GPS tracking was illegal because it had been conducted without a warrant.
The ruling noted that attaching a GPS device to an individual's vehicle to monitor its movement constitutes an illegal search and seizure under the Fourth Amendment.
The ruling failed, however, to address whether warrants must also be obtained to track suspects by using cellphone tower data and other geo-location tracking systems.
The California legislation comes as privacy groups say that numerous law enforcement agencies around the country use warrantless cellphone tracking to follow suspects in criminal cases.
Earlier this year the ACLU obtained more than 5,500 pages of internal documents from some 200 local law enforcement departments detailing their cell phone tracking practices.
All but 10 of the departments studied were found to have tracked cell phones, some of then quite frequently. Many of the departments said they obtained tracking data from phone companies without obtaining a warrant, the ACLU said.
A handful of the departments did obtain warrants though the legal standards used to obtain them varied widely, according to the ACLU.
In some cases, local police departments bypassed the phone companies entirely and purchased their own cell phone tracking technology, it added.
Earlier this month, the U.S. Court of Appeals for the Sixth Circuit entered the fray when it ruled that warrantless cell phone tracking is permissible and does not violate an individual's Fourth Amendment protections against unreasonable search and seizure.
Jaikumar Vijayan covers data security and privacy issues, financial services security and e-voting for Computerworld. Follow Jaikumar on Twitter at @jaivijayan, send e-mail to firstname.lastname@example.org or subscribe to Jaikumar's RSS feed .