Are you being tracked: that cellphone in your pocket is actually a sophisticated tracking device, and police departments are using this technology to solve crimes. What does that mean for your right to privacy?

• Author: Smith, Patricia
• Position: TECHNOLOGY

On the morning of Nov. 16, 2011, a student was kidnapped in a parking lot at Southern State Community College in Sardinia, Ohio, as she made her way to class. Her attacker threw her in the back of a pickup truck, locked her under a fiberglass cover, and sped away undetected.

But the young woman was saved by her cellphone. Using software that tracks someone's whereabouts by the GPS signal on their phone, police were able to intercept the truck on a remote country road--just 21 minutes after she called 911.

"Without it, she would have never been found," says Lt. Jim Heitkemper of the Adams County Sheriff's Office in West Union, Ohio. "She had no way of even knowing where she was because she couldn't see where she was going."

Until recently, cellphone tracking technology was used mainly by federal agents in counter-terrorism operations and drug investigations. Now, police departments across the country are increasingly using cellphone surveillance--often with little or no court oversight.

Public Safety vs. Privacy Rights

The practice is raising concerns about civil liberties in a debate that pits public safety against privacy fights. The Fourth Amendment of the Constitution protects against "unreasonable searches and seizures." That's traditionally meant that police must have either a court-issued warrant or "probable cause" to search someone's property.

But the Framers couldn't have imagined technology like cellphones and global-positioning satellites. Both store vast amounts of personal information that can be accessed remotely and without the owner's knowledge. This raises the question of what constitutes an "unreasonable search and seizure" in the 21st century.

Existing laws do not provide clear guidance: Federal wiretap laws have been outpaced by technological advances; they don't explicitly cover the use of cellphone data to pinpoint a person's location, and local court rulings vary widely across the country (see box, "Do electric "searches" violate the constitution?").

Police say phone tracking is a valuable weapon in emergencies like child abductions and suicide calls and in investigating things like drug cases and murders. In Wichita, Kansas, for example, police were recently able to track and rescue a young girl who was being taken out of state to be forced into prostitution. And cellphone records were key to the 2009 murder conviction of a New York City nightclub bouncer who made several calls as he drove to a remote spot to dump a...