With much of our lives centered on mobile devices that constantly transmit location information, courts are redefining electronic privacy rights. Cell phones and other wireless devices receive and send signals as they connect and share information with wired and wireless networks – and these signals can be traced back to the device from which they originated, possibly revealing the location of both the device and its user.

When can law enforcement officials use this location information as evidence against a defendant in criminal proceedings? Two recent decisions out of the Eleventh and Third Circuits reach different conclusions about when a warrant is required to exploit location information in a criminal matter where the Fourth Amendment protects against unreasonable searches.

Making the call: Is cell site location information within the reasonable scope of privacy?

In 2011, Quartavius Davis was charged with, among other things, robbery and knowingly using a firearm in a violent crime. During trial, the court admitted location evidence based on stored cell site information obtained without a warrant. (This information tied Davis to multiple crime scenes.)

The location evidence consisted of records obtained from wireless service providers pursuant to the Stored Communications Act, which allows the government to obtain service records with a court order rather than a warrant, which does not require a showing of probable cause. The location information used here included a record of calls made and revealed which cell tower carried the call to or from the customer. Additionally, since the cell site location information also reflects the direction of the user from the tower, investigators could extrapolate the location of the cell phone user at the time and date reflected in the call record. The fact that this information even exists might not occur to most wireless users.

So, is it unreasonable for the government to use a warrantless search against a third party to find one’s past movements and use this information in the prosecution of a crime?

On June 11, The Eleventh Circuit held that the site location information was within the subscriber’s reasonable expectation of privacy. Although a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties, the court reasoned that since cell phone users do not voluntarily share their location information with cellular wireless providers, the user’s reasonable expectation of privacy is in no way lessened. Obtaining that data without a warrant was a Fourth Amendment violation. (Two state supreme courts have reached similar decisions.)

Drawing the line: Is location information ever outside the reasonable scope of privacy expectations?

While cellular location information did fall within the reasonable scope of privacy, the circumstances in U.S. v. Stanley, also decided June 11, lead to a different result.

An officer with the Pennsylvania State Police department was investigating the online distribution of child pornography when he discovered a computer sharing 77 files suspected of containing child pornography. Upon discovering that the computer was connected to the Internet via a specific IP address, the officer obtained an order requiring Comcast to disclose the individual’s subscription information. The officer executed a search warrant, searched the home of the subscriber, and ultimately confirmed the subscriber was not responsible for the child pornography, but that another user had been connecting to the subscriber’s unsecured wireless router from a nearby location. In other words, the nearby user had been “mooching” off the neighbor’s Internet connection.

But this is where it gets interesting.

With the neighbor’s permission, the officer connected a police computer to the router in order to determine the media access control address (MAC) and the private IP address of the mooching computer. The officer then used a “MoocherHunter” device to attempt to determine the mooching computer’s location.

The aptly vernacularized MoocherHunter is a mobile tracking software tool that can be used by anyone with a laptop computer and a directional antenna. From the neighbor’s home, the officer discovered the MoocherHunter’s readings were strongest when aimed directly at Stanley’s (the defendant’s) apartment. This information was used to obtain a warrant to search Stanley’s home.

Stanley argued that the use of the MoocherHunter was an unlawful search under the U.S. Supreme Court’s decision in Kyllo. In Kyllo, officers scanned the defendant’s home with a thermal imager under the suspicion that the defendant was growing marijuana. The device revealed that certain portions of the home were unusually warm, leading police to believe that the defendant was using high powered lamps for purposes of growing marijuana. The Court held that obtaining any information from within the home by use of sense-enhancing technology constituted a search.

Surely the MoocherHunter falls into the category of “sense-enhancing technology,” right? Well, the two situations are factually distinct in that where the marijuana grower sought to confine his activity to the interior of the home, Stanley made no such effort. In fact, by exploiting his neighbor’s wireless connection, Stanley deliberately ventured beyond the privacy protections of the home, thus relieving himself of any reasonable expectation of privacy. Accordingly, no warrant was required to use the MoocherHunter technology under the circumstances.

The two cases, though factually distinguishable, are demonstrative of the continuing challenges faced by the courts as technology develops and location information becomes more accessible through electronic means. And so continues the constantly changing intersection of wireless technology and its use in criminal proceedings.

Daniel Reed