The U.S. Supreme Court recently pushed back police who use GPS tracking on cell phones to follow suspects.
The High Court said police generally must get warrants for such searches. At the same time, legal researchers published a study about courts using GPS to monitor sex offenders.
The developments illustrate how the law -- like technology -- is constantly changing. And these days, the law is usually changing to keep up with technology.
Wireless carriers collect GPS information from cell phones, unless the GPS function is disabled. Otherwise, companies can pinpoint a phone's location within 50 meters.
In Carpenter v. U.S., the Supreme Court said people have a privacy interest in their cell phone data under the Fourth Amendment. Without a warrant or exigent circumstances, the justices said, police need a warrant to get it.
The Supreme Court did not say, however, that cell phone companies are prohibited from getting the information. In other words, it left open more questions about GPS tracking than it answered.
J.J. Prescott and Ben A. McJunkin, of the University of Michigan Law School, published their study on GPS tracking the same week. They looked at forty states that currently track convicted sex offenders using GPS devices.
GPS Sex Offenders
Most legal writers say such surveillance is "civil," and therefore not an issue under the Fourth Amendment. But Prescott and McJunkin said recent cases suggest otherwise.
In Grady v. North Carolina, they noted, the Supreme Court ruled that attaching a GPS monitoring device to a sex offender was a search. Following the Carpenter decision, it seems clear that police and the courts will need to consider the issue in more situations.