Nguyen v. State

In this case, a detective submitted a geofence warrant requiring Google to disclose all cell phones located within certain areas in New Braunfels, Texas—including an entire apartment complex and a nearby interstate frontage road—over a 25-minute period. Google identified—and disclosed to law enforcement—18 devices that met the criteria. Relying on the same warrant, the detective then obtained location data for an additional two hours for all 18 devices. Only one of those 18 people turned out to be connected to the crime under investigation. Law enforcement obtained identifying information for that user from Google—again relying on the same warrant. That person moved to suppress the evidence obtained via the geofence warrant. The trial court denied the motion, and the Court of Appeals affirmed. The case is now before the Texas Court of Criminal Appeals.

The SSCI, Speech, Privacy, and Technology Project, and the ACLU of Texas filed an amicus brief urging the Court to hold that the use of geofence warrants violates the Texas Constitution. Our brief makes four principal arguments.

First, we argue that multiple provisions of the Texas Constitution protect Texans from geofence warrants, including its protections against unreasonable searches and seizures, infringements on private property, and violations of the separation of powers between different branches of government. These provisions offer even stronger protections than the Fourth Amendment when it comes to the government’s use of geofence warrants. Accordingly, we urge the Court to prohibit geofence warrants on state law grounds, regardless of whether the U.S. Supreme Court rules that such warrants violate the U.S. Constitution.

Second, we argue that geofence searches breach our reasonable expectation of privacy and intrude upon our property interest in our personal data. The location data that our cell phones generate reveals deeply private information about where we have been and how we live our lives. It reveals, for example, our presence at a doctor’s office, abortion clinic, protest, or church. And it is difficult to avoid generating location data because cell phones are so essential in modern life. The government argues that it does not even need a warrant to obtain our location data because, it says, we have “voluntarily” turned over location data to a third party—our cell service provider. In doing so, the government argues that we have given up any expectation of privacy in our data. We ask the Court to reject the government’s invocation of this “third-party doctrine.”

Third, we contend that geofence warrants violate separation-of-powers principles by allowing law enforcement officers and private companies, rather than a judge, to determine whose data is collected and de-anonymized during dragnet geofence searches.

Finally, we argue that, even if the Court concludes that geofence warrants may be permissible in some circumstances, it should issue guidance constraining how they are used. We explain that these constraints should include requiring that the temporal and geographic parameters given in a warrant be as narrow as practicable to reduce the number of innocent people swept up; that officers obtain a new warrant whenever they seek additional information that was not particularly described in the original geofence warrant; and that law enforcement agencies destroy data they collect from people who are not involved in the case.