ACLU Files Brief Arguing Warrantless GPS Tracking Is Unconstitutional

Catherine Crump
ACLU National Office

On Friday, the ACLU of Delaware filed a brief with the Delaware Supreme Court arguing that law enforcement agents should not be permitted to attach a GPS device to a car without getting a search warrant. The brief explains that because GPS tracking is an invasive form of surveillance capable of revealing many private facts about a person, a lower court was correct to conclude that, "absent exigent circumstances, the warrantless placement of a GPS device to track a suspect 24 hours a day constitutes an unlawful search."

In the case, agents attached a battery-operated GPS device to Michael Holden's car while it was parked on a public street. They did not obtain a warrant and left the device on his car for 19 days. It collected information about the vehicle's location the whole time.

Location tracking has been getting a lot of attention lately, especially when researchers revealed that iPhones stored location data even when users did not enable location-based services. The public increasingly understands that cell phones automatically transmit their location to cell phone companies whenever they are turned on, and car navigations systems depend on GPS. As location tracking technology continues to develop, who knows what devices will incorporate it or how pervasive it will become?

If you own a cell phone or drive a car, you should care about Michael Holden's case. While the specific surveillance technique involved was placing a GPS device on a car, the court's ruling may well have implications for other ways in which the government can obtain location information about a person. That is because when courts evaluate whether the Constitution permits the government to engage in a particular form of surveillance, they ask whether that surveillance invades a person's reasonable expectation of privacy. And whether you have a reasonable expectation of privacy in not having a GPS device attached to your car depends on whether you have a privacy interest in your location more generally.

In other words, whether Michael Holden has a right not to have a GPS device attached to his car unless the government gets a warrant may impact your right not to have the government obtain your location records from your cell phone carrier without a warrant.

To explain why GPS tracking is invasive — particularly over long stretches of time — it's hard to do better than these words from a Washington, D.C., federal appeals court decision:

A person who knows all of another's travels can deduce whether he is a weekly churchgoer, a heavy drinker, a regular at the gym, an unfaithful husband, an outpatient receiving medical treatment, an associate of particular individuals or political groups — and not just one such fact about a person, but all such facts.

The Delaware Supreme Court should recognize the invasive nature of GPS tracking and require the government to obtain a warrant to engage in it.