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Cell-Site Simulators: Police Use Military Technology to Reach out and Spy on You

by Christopher Zoukis

Law enforcement agencies nationwide are employing technology, designed for military use in foreign lands, in order to track the location of U.S. citizens on American soil. And authorities — all the way up to the FBI — have gone to great lengths to hide the surveillance system from the public, the criminal defense bar, and even the judiciary.

Cell-site simulators, also known as stingrays, trick cellphones into connecting to the device instead of an actual cell tower. Police operating the devices can track the location of all connected cellphones within a certain radius, and also can potentially intercept metadata about phone calls (the number called and length of the call), the content of phone calls and text messages, as well as the nature of data usage — including browser information. All of this takes place unbeknownst to users whose cellphones have been hijacked.

The growing use of stingray trackers has alarmed privacy advocates and criminal defense attorneys, but concerns over their use have been met with silence from police and prosecutors. Law enforcement in at least 23 states use the technology, as do a host of federal agencies.

In some cases, prosecutors have gone so far as to dismiss criminal charges to avoid disclosing any information about stingray use. Incredibly, the FBI requires local law enforcement authorities to accept a comprehensive nondisclosure agreement prior to being allowed to use stingrays. The agreements require police and prosecutors to refuse to hand over information about stingray technology or usage to defense attorneys and judges alike.

Successful Freedom of Information Act litigation, as well as the diligent and coordinated efforts of criminal defense attorneys, is leading to greater public and judicial awareness of the nature and use of stingrays.

Courts are beginning to grapple with the Fourth Amendment implications of their usage. Even the Department of Justice (“DOJ”) recognizes that their intrusive nature implicates constitutional privacy protections. DOJ policy now requires that all federal law-enforcement agencies obtain a full, probable cause-supported search warrant prior to employing the devices.

But the DOJ policy is not law, and not all courts require law enforcement to obtain a warrant prior to using a stingray. Moreover, no legal changes short of an outright ban on the devices will change what they can do: hijack a cellphone and force it to report in to the government, all while it sits quietly in an unsuspecting user’s pocket.

The Stingray Found Terrorists, Now It Will Find You

Cell-site simulators were first developed over two decades ago, as military technology. According to a 2016 investigative report by The Daily Dot, the original stingray was developed by Harris Corporation, in conjunction with the Pentagon and federal intelligence agencies. The technology was designed for use on foreign battlefields in the war on terror and for use in other national security-related arenas.

Harris, based in Melbourne, Florida, remains the leading manufacturer of cell-site simulators. The company makes a variety of models, including the first-generation Stingray and newer models such as HailStorm, ArrowHead, AmberJack, and KingFish. The devices cost law enforcement agencies between $200,000 and $500,000 each.

According to, Harris Corporation received $3.6 million in federal funding and held more than 2,000 federal contracts in 2017 alone.

Law enforcement agencies in 23 states and the District of Columbia were using stingray technology as of 2016. And, according to a 2017 Cato Institute report, multiple federal agencies in addition to the FBI use the technology, including the ATF, DHS, ICE, DEA, NSA, U.S. Marshals Service, and even the IRS. The Army, Navy, Marine Corps, and National Guard use cell-site simulator technology as well.

Cell-site simulators are suitcase-size devices that mimic the signal of actual cellphone towers – they even emit a stronger signal than legitimate towers. And, because cellphones are programmed to seek the best signal, all phones within the radius of the signal will connect to the device. According to the Electronic Frontier Foundation (“EFF”), cell-site simulators that are installed in law-enforcement vehicles allow the devices to snoop on up to 10,000 phones at a time.

When a cellphone connects to a stingray, actual phone service is disrupted. While the devices search the phone, no calls can be made, no text messages can be sent or received, and no data can be transmitted. Other than the data transmitted to the stingray, of course.

According to EFF, cell-site simulators can determine the location of all connected phones. They also can access identifying data about the phone, including unique information such as international mobile subscriber identity (“IMSI”) numbers or electronic serial numbers (“ESN”). Further, stingrays can intercept unencrypted phone calls, text messages, and data content. They can even be configured to divert calls and texts, edit messages, and spoof the identity of a caller in text messages and phone calls.

Police agencies use stingray devices when they know the uniquely identifying IMSI number of a target phone, which is obtained from a cellphone carrier, usually through a subpoena. With the number in hand, the stingray operator deploys the device near where the target phone is believed to be. The machine then goes to work, hijacking every phone in the area of 500 meters (547 yards) or more. As a phone connects to the stingray, the device “rips” its unique IMSI number and compares it against the target phone’s number. Ideally, when the number doesn’t match, the stingray disconnects the phone. This process is repeated until a match is found.

According to the Cato Institute report, police can even use the stingray to find a phone without knowing its IMSI number. Using visual surveillance and stingray cellphone pinging, law enforcement can follow a suspect and, as other phones disconnect from the device, confirm which IMSI number is associated with the suspect’s phone. This method allows law enforcement to forego the process of obtaining a subpoena.

Once the stingray operator confirms the device is connected to the target phone, the machine can pinpoint the phone’s location to within a radius of 6 feet. If the stingray is mobile, police operators can follow the target phone wherever it goes, including into private homes, doctors’ offices, and other locations that would traditionally require a specific and detailed warrant to search.

The Fourth Amendment provides that people have a right to “be secure in their persons, houses, papers, and effects against unreasonable searches and seizures.” Those rights are protected by the judiciary, which generally requires proof of probable cause prior to the issuance of a search warrant. But, according to a July 2016 article in Harvard Law School’s National Security Journal, law enforcement agencies have long used stingray technology to run roughshod over the Fourth Amendment, and no one seems to have known about it.

“In the past decade, 50 local or state police and 13 federal law enforcement agencies have used [cell-site simulators] to track the location of targets in real time, with an accuracy of up to two meters, without a warrant, without disclosure to the public of its use, and without any legal protections for third-party data or privacy within the home,” wrote article author Christopher Izant.

It’s fair to ask why so few public officials and judges know anything about stingray technology. The answer, it seems, is that an unholy alliance of corporate, national security, and local law enforcement interests has conspired to hide the capabilities of these powerful devices. Lack of meaningful oversight is clearly in their best interest.

Secrecy vs. Public Safety

Cell-site simulator technology is in use by law-enforcement agencies nationwide. Despite the growing popularity of these powerful devices, little is known about their exact capabilities. Perhaps more importantly, even less is known about what police are doing with their stingrays.

This is because law enforcement agencies and device manufacturers have gone to great lengths to keep information about stingray capabilities, and use, secret. Harris Corporation, for example, has worked with the FBI to create a nondisclosure agreement (“NDA”) that prevents local and state law enforcement from revealing any information about the stingray, including its capabilities, uses, and in some cases, its very existence. The FBI is responsible for coordinating the sale and use of cell-site simulators to local agencies, and prior to any department obtaining one of the devices, it must agree to a highly restrictive NDA.

Several examples of the required NDA have been obtained by journalists and civil liberties organizations. The agreement between the Erie County, New York, Sheriff’s Office and the FBI provides that the county sheriff may not disclose any information about the stingray device to anyone at any point, including in applications for search warrants, in discovery, in response to a direct order from a court, or during a trial. In practice, this means that an agency subject to an NDA can use the device to track an individual, but cannot tell a court or defense attorney that it did so.

That’s not all that these NDAs require. If law enforcement determines that a prosecutor will be required to violate the NDA in pursuit of a conviction, he must notify the FBI, who may then intervene or even require that local authorities drop the case in order to keep information about the device secret. The Guardian obtained an NDA entered into by the Hillsborough County Sheriff’s Office which includes such language, and reads in part:

“The Florida Department of Law Enforcement will, at the request of the FBI, seek dismissal of the case in lieu of providing, or allowing others to use or provide, any information concerning the Harris Corporation wireless collection equipment/technology, its associated software, operating manuals, and any related documentation.”

Sometimes law enforcement agencies deny that an NDA even exists. When the American Civil Liberties Union (“ACLU”) filed a Freedom of Information Act request for details of stingray usage in a Delaware case, the state refused to release any information. The ACLU then requested a copy of the NDA that was preventing the disclosure, and the state went so far as to deny that such an agreement ever existed, calling it a “mythical document.”

“Their position was that we were just inventing the idea that they would have an NDA with Harris,” ACLU attorney Ryan Tack-Hooper told

But then the state miraculously found the NDA, which prohibited disclosures regarding the stingray device to anyone, including elected officials and even police officers who did not have a “need to know.” Tack-Hooper said the discovery of the NDA was “highly suspicious.”

“Their story was that they found this in a drawer somewhere,” he said.

Law enforcement authorities also try to prevent disclosure of stingray evidence by engaging in a dubious investigative practice known as “parallel construction.” According to a report, “parallel construction is when law enforcement originally obtains evidence through a secret surveillance program, then tries to seek it out again, via normal procedure.” Parallel construction, incidentally, is also used when law enforcement originally obtains evidence in a manner that might be referred to as “unconstitutional” if one were being charitable, or “illegal” if not.

In practice, law enforcement often obscures the use of secret surveillance systems like the stingray by purposely writing reports in an inscrutable manner. Nathan Freed Wessler, a staff attorney at the ACLU’s Speech, Privacy and Technology project, said it can be difficult for defense attorneys to determine whether a stingray was used in a criminal investigation.

“We’ve seen plenty of examples where the police officers in those reports write ‘we located the suspect based on information from a confidential source;’ they use intentionally vague language,” Wessler said. “It sounds like a human informant or something else, not like a sophisticated surveillance device.”

Another example of parallel construction is a “whisper” stop. In this scenario, law enforcement has information about a target vehicle obtained from a secret source, such as a stingray, but manufactures alternative probable cause to support the stop. Sarah St. Vincent, the author of a Human Rights Watch report on parallel construction, said the whisper stop is often based on information obtained from federal agencies.

“Sometimes when tips come through, the federal authorities don’t even tell the local authorities what they’re looking for,” St. Vincent said.

The federal government has taken extreme action to prevent the disclosure of information relating to cell-site simulators. When the ACLU obtained a court order requiring the Sarasota, Florida, police to turn over stingray documentation in 2014, the U.S. Marshals staged a pre-dawn raid on the Sarasota Police Department in order to confiscate the documentation before it could be disclosed.

Law enforcement authorities routinely justify their efforts to keep cell-site simulator technology secret by invoking national security. According to Baltimore County Police Cpl. Shawn Vinson, the FBI “believes that [stingray] technology is a vital tool in homeland security operations and disclosures of this technology could expose ways to subvert this investigative tool to terrorists and criminals alike.” But as a 2017 Cato Institute report notes, “Terrorists and drug kingpins long ago concluded that their cell phones were liabilities,” and “[e]ven if we assume that keeping these capabilities secret at one time justified a regime of immense secrecy, the secret is out now.”

Indeed, despite the widespread use of cell-site simulator technology, Jennifer Lynch of EFF told Capital News Service that she did not know of any cases where terrorism was uncovered by local police through the use of a stingray.

“I don’t think it’s happened at all,” said Lynch.

Cell-site simulators are regularly used for run-of-the-mill police investigations, however. According to USA Today, a Baltimore police detective testified in 2015 that Baltimore cops used cell-site simulators more than 4,300 times since 2007. And the ACLU has amassed a list of at least 300 cases in which they believe a stingray was used.

When law enforcement officers attempt to invoke an NDA or national security in order to avoid disclosing stingray information in court, they often find themselves facing a hostile judge or defense attorney. In 2015, a Baltimore judge threatened to hold a detective in contempt when he refused to disclose stingray information because, he said, “the Department of Justice prohibits the access and disclosure of those items.”

“You don’t have a nondisclosure agreement with the court,” Judge Barry Williams told the detective.

In a different Maryland case, a judge refused to allow a cellphone into evidence when the testifying police officer would not say how he obtained probable cause to stop the defendant’s vehicle. The brief exchange between the officer and the judge illustrates the problems that lack of candor can cause in court.

Judge: It’s a simple question. Why was he stopped? What was the, it was a warrantless arrest. Why was he stopped?

That’s the question she’s asked. He can answer the question. Why did you stop him?

Police Officer: This kind of goes into Homeland Security issues, Your Honor.

Judge: OK, if it goes into Homeland Security issues, then the phone doesn’t come in. Okay. Step down, thank you. I mean, this is simple. You can’t just stop someone and not give me a reason, State, and you know that.

Baltimore public defender Janine Meckler represented the defendant and echoed the judge’s concern over law enforcement’s lack of transparency.

“I have a right to know why my client is stopped,” Meckler said. “You can’t just come in here carte blanche, ‘Oh, it’s national security.’”

Privacy vs. Public Safety

Prosecutors avoid these situations by dropping cases or offering plea deals when they cannot or will not disclose stingray information. David Rocah, senior staff attorney at ACLU of Maryland, said the government can’t have it both ways.

“That’s something that law enforcement has to account for, that they’re putting secrecy ahead of public safety,” said Rocah. “You cannot say these things are critical to public safety and then sell out public safety in the same breath.”

For criminal defense attorneys, stingrays present significant problems. When an advocate is not told that a stingray was used, she cannot challenge how the machine works, or whether it was operated properly. Jason Ricke, a public defender in Virginia, said that prosecutors playing coy about stingray use interferes with his job.

“The main problem is that the police may be doing something illegal, and we have to use mental gymnastics to try and uncover these secret aspects of an investigation that are never written down and turned over to us,” Ricke said. “The police may be violating our clients’ rights and we will never know it.”

Bruce R. Jacob, a law professor and the former dean of Stetson Law School in Florida, said the secrecy surrounding stingray use goes beyond just the rights of an individual defendant.

“It reminds me of what happens in totalitarian countries: You don’t know what the hell is going on,” said Jacob.

Law enforcement authorities will continue to use terrorism and national security to justify the use of the highly intrusive stingray technology. But concerns over terrorists invading the town pumpkin festival (actually cited to obtain federal equipment for local law enforcement in one case) are not realistic. The real concern is that local law enforcement agencies are using these devices to investigate all kinds of crimes, often without going through the traditional procedures required prior to a search, namely seeking a warrant.

“The problem is that you can’t have it both ways,” said EFF attorney Hanni Fakhoury. “You can’t have it be some super-secret national security terrorist finder and then use it to solve petty crimes.”

Constitutional Considerations

Search and surveillance techniques used by law enforcement are subject to procedures and safeguards intended to protect privacy and prevent unreasonable search and seizure. It is a bedrock principle of Fourth Amendment jurisprudence that the police may not search a citizen’s home, car, or pocket without probable cause, usually supported by a search warrant. But the law does not always keep pace with developing technology. Cell-site simulators are an example of how new technology can be leveraged to skirt constitutional limitations on the power of the police.

In the landmark case of Katz v. United States, 389 U.S. 347 (1967), the United States Supreme Court established that a police search requires a warrant supported by probable cause when an individual has a reasonable expectation of privacy in the subject of the search. The Court has since ruled that an expectation of privacy can disappear when an individual voluntarily conveys the information subject to search to a third party. Cellphones voluntarily convey information to a third party at all times, and thus are arguably not entitled to the probable cause-supported protection of a warrant.

In reality, of course, cellphone users have an expectation of privacy in their cellphone communications. The Supreme Court seems to be prepared to rethink the idea of the third-party doctrine, at least in the case of cellphones, which Chief Justice Roberts once said “are now such a pervasive and insistent part of daily life that the proverbial visitor from Mars might conclude that they were an important feature of human anatomy.” But as of now, limitations on law enforcement searches of cellphones are not clearly defined.

Because there has been no legislation or Supreme Court ruling clearly establishing whether law enforcement needs probable cause (or any cause) to use cell-site simulator technology, law enforcement policies governing their use vary across the nation. Some agencies have settled for obtaining “pen register” or “trap and trace” orders, which require less evidence of a crime than a warrant would. Other agencies require the issuance of a full warrant prior to using a stingray. Many law enforcement agencies have no policy at all, and officers use the devices at will.

For its part, the Department of Justice appears to see the writing on the wall and now requires that federal law enforcement officials seek and obtain a warrant prior to using a stingray. The policy, established in September 2015, applies only to domestic criminal investigations. In addition to the warrant requirement, the policy prohibits the use of stingray functions or add-ons that enable content collection and mandates that any third-party cell data be deleted once the target phone is located.

The DOJ policy, however, is just that — policy. It does not have the force of law and has no impact on how local law enforcement use their stingrays. Moreover, relying on the executive branch to police itself, especially when it comes to a powerful investigative tool, may be a fool’s errand. Supreme Court Justice Sotomayor made this point in an opinion concurring with the Court’s ruling in United States v. Jones, 132 S. Ct. 945 (2012). There, the Justice questioned the “appropriateness of entrusting to the Executive, in the absence of any oversight from a coordinate branch, a tool so amenable to misuse, especially in light of the Fourth Amendment’s goal to curb arbitrary exercises of police power [] and prevent ‘a tool permeating police surveillance.’”

The behavior of law enforcement with respect to cell-site simulators underscores the need for legislative and judicial oversight. Law enforcement agencies all the way up to the FBI have been determined to prevent courts from weighing in on the constitutionality of stingray usage. NDAs prevent disclosure of the device’s capabilities and usage, and prosecutors have been willing to dismiss cases or offer highly favorable plea deals rather than reveal to a judge how they obtained their evidence. According to the Cato Institute report, this kind of secretive and fishy behavior does not provide cause to trust the executive branch to police itself, and it creates separation of power issues.

“When federal-state partnerships preclude executive officers of state and local agencies from informing judges, legislators, or the general public about their capabilities (or even the fact that they’ve partnered with the federal government in the first place), separation of powers questions arise,” wrote the report authors.

As the power of the cell-site simulator has become better understood, courts have begun to take a more assertive role in policing their use. In March 2016, Maryland’s Court of Special Appeals held in Andrews v. State, 227 Md. App. 350 (Md. Ct. Spec. App. 2016), that the use of a stingray to locate a cellphone inside a home constitutes a search for purposes of the Fourth Amendment and thus requires a full, probable cause-supported warrant. Prior to the ruling, police in Baltimore obtained only a pen register/trap and trace order before deploying a stingray. The court called police conduct in the case misleading and “unconstitutionally intrusive.” The three-judge panel also highlighted the separation of powers issue raised by police secrecy.

“A nondisclosure agreement that prevents law enforcement from providing details sufficient to assure the court that a novel method of conducting a search is a reasonable intrusion made in a proper manner and justified by the circumstances obstructs the court’s ability to make the necessary constitutional appraisal,” the justices wrote.

A New York state trial judge also ruled that a pen register/trap and trace order is insufficient to support the use of a stingray. In the November 2017 case People v. Gordon, NY Slip. Op. 27634, Supreme Court Judge Martin Murphy said “the use of a cell site simulator intrudes upon an individual’s reasonable expectation of privacy, acting as an instrument of eavesdropping and requires a separate warrant supported by probable cause rather than a mere pen register/trap and trace order such as the one obtained in this case by the NYPD.”

In Jones v. United States, 168 A.3d 703 (D.C. 2017), the District of Columbia Court of Appeals came to a similar conclusion. There, the court said cellphone users retain a legitimate expectation of privacy in their “intimate personal information,” including their location. As such, said Associate Judge Corrine A. Beckwith, joined by Senior Judge Michael W. Farrell, “the use of a cell-site simulator to locate [the defendant’s] phone invaded a reasonable expectation of privacy and was thus a search.”

Nathan F. Wessler of the ACLU helped argue the case with the D.C. Public Defender Service and praised the court’s ruling.

“This opinion joins the growing chorus of courts holding that the Fourth Amendment protects against warrantless use of invasive, covert technology to track people’s phones,” said Wessler. “We applaud today’s opinion for erecting sensible and strong protections against the government violating people’s privacy in the digital age.”

There has been limited consideration of the constitutional parameters of a cell-site simulator in federal court, due in large part to the secrecy surrounding the technology. The Chief U.S. District Judge of the U.S. District Court for the Northern District of California ruled in late 2017 that the use of a stingray constitutes a search under the Fourth Amendment and thus requires a warrant. The judge, however, also found “exigent circumstances” and reason to allow a “good faith exemption” on the facts in the case, both of which are regularly used to avoid the necessity of a warrant, so the stingray use withstood the defendant’s challenge. But Judge Phyllis Hamilton did make it clear that the use of stingray technology implicates the Fourth Amendment.

“Cell phone users have an expectation of privacy in their cell phone location in real time and that society is prepared to recognize that expectation as reasonable,” she wrote.

But the United States Supreme Court, the final arbiter of all constitutional issues, has yet to weigh in on this issue. Justice Samuel Alito suggested in a 2014 opinion that because technology moves so fast, and courts move so slow, legislatures should not wait for the courts on the issue of privacy and cell-site simulator technology.

“[I]t would be very unfortunate if privacy protection in the 21st Century were left primarily to the federal courts using the blunt instrument of the Fourth Amendment,” wrote Justice Alito, concurring with the majority in Riley v. California, 134 S. Ct. 2473 (2014). “Legislatures, elected by the people, are in a better position than we are to assess and respond to the changes that have already occurred and those that almost certainly will take place in the future.”

Congress, however, has not acted on this important issue. Former Rep. Jason Chaffetz (R-UT) introduced the Stingray Protection Act in 2015, but the bill, which would have made it a crime to use a stingray without a warrant, did not become law. And in August 2017, four U.S. Senators sent a letter to Attorney General Jeff Sessions in which they expressed concern over federal use of stingrays, “including that stingrays sent probing signals into the homes of everyone in the target location.” But as of the date of this article, Congress has taken no action to regulate stingray usage.

There are multiple reasons why Congress is the best choice to rein in the invasive stingray technology. According to the 2016 Harvard Law School’s National Security Journal article, Congress can “proscribe prospective rules for procedure in specific criminal investigations.” Congress has, in fact, legislated many rules regulating investigative techniques. The Wiretap Act, Pen Register and Trap and Trace Device Statute, Electronic Communications Privacy Act, and Communications Assistance to Law Enforcement Act are prime examples.

Congress also is in a much better position to enact new rules or amend existing laws than any court, including the Supreme Court. In addition, Congress can regulate the actions of non-governmental actors, where courts are limited to applying the Fourth Amendment to government officials.

Perhaps most importantly, as highlighted by Justice Alito, Congress can deal with complex, emerging technology such as the stingray, in a much more timely fashion than any court. Congress also can convene hearings and elicit testimony from stakeholders and experts. Unfortunately, despite the concerns of federal lawmakers and attempted legislation, Congress has failed to act.

State legislative bodies, however, have begun to make progress in regulating the use of cell-site simulators. California, Washington, and Virginia have laws in place that regulate when and how law enforcement may use a stingray. Other states, including Florida, Missouri, and Rhode Island, have bills pending that would ban the warrantless use of stingray technology.

The Time to Act Is Now

The Fourth Amendment guarantees citizens the right to be free from unreasonable searches and seizures. There is little doubt that law enforcement use of military technology to track the location of citizens in real time constitutes a search and an entirely unreasonable one at that. Cellphones are ubiquitous, and that makes the stingray a powerful investigative weapon. The fact that nearly every American has a cellphone with them at all times also means that a device whose sole purpose is to hijack cellphones is also a very dangerous and invasive weapon.

Decades after the development of stingray technology, the legislative and judicial branches know precious little about how these devices work. It is long past time for law enforcement agencies nationwide to come clean about the hacking and jamming capabilities of cell-site simulators. Congress must act to ensure that the privacy rights of every American are protected, and courts must do more to ensure that law enforcement officers are not pulling the wool over their eyes. Because, according to the Cato Institute, stingrays are the tip of the technological iceberg.

“Stingray surveillance raises many novel political and legal issues, yet cell phone trackers are only the vanguard,” said the 2017 report authors. “Police technology will continue to become more expansive and powerful, and the longer it takes legislatures and courts to produce a legal framework capable of keeping up with technology and ensuring that constitutional rights are protected, the more threatening the surveillance state will become.” 


Additional Sources: “Stingray: A New Frontier in Police Surveillance” by Cato Institute (January 2017); Harris Corporation, “Letter & Nondisclosure Agreement” (July 12, 2010); Department of Justice, “Policy Guidance: Use of Cell-Site Simulator Technology” (September 3, 2015)

Christopher Zoukis, the author of Federal Prison Handbook (Middle Street Publishing, 2017), Prison Education Guide (PLN Publishing, 2016), and College for Convicts (McFarland & Co., 2014), is a contributing writer to Prison Legal News, Criminal Legal News, Huffington Post, New York Daily News, and New York Journal of Books. He can be found online at

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