Why Police Should Be Required to Get a Warrant to Use Cell-Site-Simulators (aka, "stingrays")

Legislation heard this week in the Texas House Criminal Jurisprudence Committee, HB 352 (Blanco) would require warrants for Texas law enforcement to use so-called “stingrays” or “cell-site simulators” to track people's cell phones, and provide more transparency surrounding use of these devices.

So-called “Stingrays” or cell-site simulators are examples of relatively new surveillance techniques hovering at the bleeding edge of both cell-phone technology and Fourth Amendment jurisprudence. Because their use has been largely shrouded in secrecy and few clear precedents exist to model limits on this tech, the handful of law-enforcement agencies using it have until now operated in virtually a regulation-free zone.

Rep. Cesar Blanco, a third-term Democrat and former Navy intelligence office, understands signals intelligence better than probably any other legislator and is an excellent bill sponsor for this topic.

How Cell-Site Simulators Work
Cell-site simulators work by tricking your cell phone into believing it’s attaching to a legitimate cell-phone tower, which it “pings” periodically to make sure the phone is ready to make a call. This means that, when targeted users (or others in their vicinity) make a phone call, it’s routed through the cell-site simulator instead of the nearest tower. Representations by Houston PD at Monday’s hearing about the limited nature of the technology understated its capacity.

Cell-site simulators hijack and divert cell-phone signals from their commercial carrier’s network, making it more similar to a wiretap than a “pen register.” Some models of cell-site simulators allow full-blown wiretapping; others provide access to metadata from calls and callers; others may only provide information on signal strength and direction, allowing investigators to triangulate location with just a few measurements. It all depends on how much functionality an agency chose to pay for; the device is capturing the entire signal and can let investigators access any or all of it.

Movement toward ‘stingray’ warrant requirement
The US Supreme Court has not yet ruled on so-called “stingrays,” but several states already require warrants for cell-site simulator use with no ill effects. (Virginia, Washington, Utah, Minnesota, and California.)

On December 19, 2016, the U.S. House Committee on Oversight and Government Reform issued a comprehensive, bipartisan report on law-enforcement use of cell-site simulators and recommended legislation that would require “probable cause based warrants” to “ensure that the use of cell-site simulators and other similar tools does not infringe on the rights guaranteed in the Constitution.”

The US Department of Homeland Security established a policy of seeking a warrant for use of cell-site simulator technology with limited exceptions for exigent circumstances.

Finally, civil libertarians have persuasively argued that, when a cell phone inside someone’s home is targeted with signal interception via a cell-site-simulator device, it per se violates the Fourth Amendment right to security from unreasonable searches of one’s “houses, papers and effects.” (Traditionally, Fourth-Amendment protections inside the home have been much stronger than elsewhere.)

Secrecy breeds mistrust
At Monday’s hearing, police expressed fears that innocent people might be hurt if information from search warrant affidavits about how and when police used the technology ever surfaced. But search-warrant affidavits have been public records since the dawn of the Republic. The more significant concern is that law enforcement will use the technology unaccountably and secrecy will protect them.

Not only does the public deserve to know when the government is using invasive surveillance technology, undue secrecy creates systemic problems. In Houston, police have even kept prosecutors in the dark when stingray tech was used.

Texas legislators should extend the same warrant requirement mandated by the Supreme Court in US v. Carpenter to cell-site simulator devices. This shadowy practice has flourished for too long on the edges of modern technology and privacy law. HB 352 is Texas’ opportunity to begin to restrain and regulate it.

See prior, related Grits coverage.

Carpenter codification non-controversial so far

Rep. Cesar Blanco also filed a related piece of legislation, HB 353, which essentially codifies the US Supreme Court case US v. Carpenter requiring a search warrant for the government to access cell-phone location data held by wireless cell-phone carriers. (Readers may recall Grits' poetic ode to the case after the oral arguments.)

Unlike the stingray legislation, no one opposed this bill. There was a half-hearted effort by a cop speaking "on" the legislation to preserve the real-time vs. historic location information distinction that the Texas Court of Criminal Appeals tried to stake out in Sims v. Texas. But it's awfully hard to defend the idea that the government has a right to know where you are at any given time, in real time, without demonstrating probable cause. From the solitude of Judge Barbara Hervey's chambers at the Court of Criminal Appeals, one perhaps can make that strained argument without fear of recrimination. At a legislative hearing, nobody even tried. 

The reality is, even if they tried to do a Less-Than Carpenter Codification, this area of constitutional law is fluid and trending toward requiring more warrants for surveillance, not less. As such, Grits imagines that trying to short-change the warrant requirement could result in future federal court decisions rendering the language anachronistic. Rep. Blanco's approach is the wiser one.