In the “golden age of surveillance,” our cellphones are subject to governmental surveillance. Government enforcement agencies have two ways to surveil cellphones. They can do it through a phone company, or directly using a Stingray device.

United States v. Davis Implies that Cell-phones Surveillance Through A Phone Company Does Not Subject to Fourth Amendment Prohibition, and Thus Calls for A Legislative Intervention.  

A recent en banc decision in United States v. Davis implies that privacy in cell site location does not qualify for Fourth Amendment protection, and government enforcement agencies can compel cell sites to produce cell site location data without obtaining a search warrant.

When a cellular phone user makes a call, the user’s cell-phone sends a signal often to the closest cell site that serves a particular geographic area. Obtaining cell site location data is useful for criminal investigation because it allows a police officer to draw the approximate location of a cell-phone user from the “historical, current, or prospective” locations of the cell sites that receive the signal from his or her cellphone.

The en banc decision in Davis in the Eleventh Circuit reversed its previous holding that applied the Fourth Amendment to cell site location data. This decision eliminated the circuit split previously existed between the Eleventh Circuit and the Fifth and Third Circuit. Now, all three Federal Circuit Courts agree that the Fourth Amendment does not protect individual cell site location data from warrantless search.

The en banc decision focused on whether there were both subjective and objective expectations of privacy, and was based primarily on analogies with the factual scenarios in precedents that touch on the application of Fourth Amendment. In one example, the Court compared cell site location data and bank account records in United States v. Miller, and held that the individual “had no protectable Fourth Amendment interest in the [bank] account records because the documents were: (1) business records of transactions to which the banks were parties and (2) [the individual] voluntarily conveyed the information to the banks.”

The bank account analogy does not justify the conclusion that cell site location data fails the reasonable-expectation-of-privacy test, because cell-phone users don’t fully understand how much information they are submitting to the cell sites when they make phone calls or send and receive messages, whereas in the analogies the Court made, including the bank account one, the actors were fully aware of the consequences of their acts.

Additionally, today’s cell-phone users have different demand of privacy. Indeed, the “expectation-of-privacy” test creates unavoidable uncertainty because the societal expectation of privacy changes overtime. Therefore, legislative bodies are in a better position to ensure that the law remaining effective and proactive in meeting the privacy demand by each generation.

An Ideal Stingray Law Should Incorporate Fourth Amendment Protection Without Overly Burdening Law Enforcement Agencies.

Compelling the cell sites to produce location data is not the only means through which the law enforcement agencies can acquire location information. With “Stingray” technology, law enforcement agencies are able to make themselves or their vehicles an effective “cell site.” In response, several states, and now U.S. Department of Justice, enacted its own version of Stingray Law.

Stingray is a cellphone-tracking technology that can trick cellphones “into believing it’s a cell tower to give law enforcers the ability to find a phone user and gather data.” Stingray technology has been widely and frequently used by law enforcement agencies. At least fifty-three agencies in twenty-one states and the District of Columbia have been identified to own Stingrays, and the number is still growing. Stingray devices result in more invasive surveillance, because in addition to cellphone locations, law enforcement agencies can obtain the content of calls, text messages, numbers dialed, and web pages visited by the cell-phone holders.

In response to the use of Stingray technology, state and federal legislatures have signed or are planning to sign into law different versions of “anti-surveillance” bills (Texas, Washington, California). U.S. Department of Justice and a handful of states have similar Stingray laws that mirror a Fourth Amendment protection that requires a warrant. Other states, such as California, adopts a more flexible approach that might bring extra burden to law enforcement agencies.

The U.S. Department of Justice “announced that, except in emergency situations, federal agents would now seek warrants before using Stingrays.Texas requires law enforcers to obtain a warrant before using Stingray technology to track people and gather data from their cellphones. Similarly, Washington Stingray law requires that “a judge find there is probable cause that use of a Stingray will lead to evidence of criminal activity,” but imposes an extra burden on the law enforcement agencies to “provide judges with specific details about cell site simulators and how they will be used in a given case.” Minnesota, like the U.S. Department of Justice, requires a tracking warrant upon a showing that there is probably cause the person who possesses an electronic device is committing, has committed, or is about to commit a crime.” Minnesota also recognizes some exceptions that justify a warrantless search under emergency situations where the gravity of offense is high. The approach by Minnesota and U.S. Department of Justice is consistent with exception under the Fourth Amendment that allows a warrantless search with the existence of an exigent-circumstance. A principal factor to be considered in the exigent-circumstances calculus is the gravity of the underlying offense.

On the other hand, California attempts to solve the problem created by Stingray technology through a more flexible approach. California passed a bill on May 22, 2015, that “limits the use of Stingrays to track the location of phones and sweep up electronic communications, not only protecting privacy in California, but also hindering part of the federal surveillance state.” The California Stingray law prohibits a local agency from acquiring or using a Stingray device unless “approved by a resolution or ordinance adopted by its legislative body at a regularly scheduled public meeting where the public has a reasonable opportunity to comment.” “The bill also requires the resolution or ordinance to set forth policies on Stingray use based on specific guidelines outlined in the legislation.”

Stingray laws aim to overcome the “reasonable-expectation of privacy” barrier in applying Fourth Amendment to the protection of cell site location data. Because individuals don’t fully understand the underlying technology, courts cannot predict their expectation of privacy from their activities. The ideal Stingray law applies the Fourth Amendment requirement to the case of Stingray technology and location data, and recognizes similar exceptions (i.e. exigent-circumstances exceptions). In this sense, the U.S. Department of Justice and Minnesota have set a good example for rest of the states in regulating the use of Stingray technology.


Hilda Li is a J.D. candidate, 2017, at NYU School of Law.