As I discussed here, the Fourth Circuit recently ruled in United States v. Graham, __ F.3d __, 2015 WL 4637931 (4th Cir. Aug. 5, 2015), that an officer who obtained two suspects’ cell site location information (CSLI) without a search warrant violated the Fourth Amendment. (The officer used a court order based on a lower standard, as purportedly authorized by the relevant federal statute, 18 U.S.C. § 2703(d).) I’ve had a number of practical questions about Graham from officers, agency attorneys, and judges, and I thought that I would collect some of the questions here. Continue reading
Tag Archives: tracking
On Tuesday, the Eleventh Circuit ruled, en banc, that law enforcement may obtain historical cell site location information without a search warrant, using a court order based on less than probable cause. There’s a controversy over what legal standard should govern law enforcement access to location information, and the Eleventh Circuit’s ruling is likely to be influential in the debate. This post explains the issue and puts the new decision in context. Continue reading →
I’m happy to announce that my book on digital evidence is now available. There are five chapters, covering (1) search warrants for digital devices, (2) warrantless searches of digital devices, (3) law enforcement access to electronic communications, (4) tracking devices, and (5) the admissibility of electronic evidence. Continue reading →
This weekend, the Charlotte Observer ran this article, entitled Charlotte Police Investigators Secretly Track Cellphones. The article concerns the use of so-called stingrays, also known as IMSI catchers or cell site simulators. They are machines that simulate cell towers and connect with the cellular telephones located nearby. Officers frequently use them to triangulate the location of a suspect – or more precisely, the location of a suspect’s phone. There’s a controversy about the legal status of these devices, which I’ll summarize in this post. Continue reading →
I’ve had more and more questions about introducing GPS tracking data in criminal trials. When I think about digital evidence, I think about authentication as the first hurdle. This post summarizes the law regarding the authentication of GPS data.
GPS data may come into criminal cases in several ways: because law enforcement placed a tracking device on a suspect’s vehicle; because a suspect was wearing a GPS tracking bracelet as a condition of probation or pretrial release; because law enforcement seized a cell phone or other device containing GPS data from a suspect; and so on. Although each situation presents slightly different considerations, it should often be possible to authenticate such data under Rule 901(b)(1) (testimony of a witness with knowledge that the data is what it is claimed to be), Rule 901(b)(9) (concerning “[e]vidence describing a process or system used to produce a result and showing that the process or system produces an accurate result”), or some combination of the two.
The leading case in North Carolina is State v. Jackson, __ N.C. App. __, 748 S.E.2d 50 (2013). The defendant committed a sexual assault while wearing a GPS tracking device as a condition of his pretrial release. The supervisor of the electronic monitoring unit testified regarding how the tracking device worked. The defendant argued that the tracking data was not properly authenticated, but the court of appeals ruled to the contrary. However, the court did not analyze the authentication issue in detail — instead focusing mainly on whether the data were inadmissible hearsay — so the opinion is useful mainly for cases that have similar facts.
A few cases from other jurisdictions provide more general guidance. Most courts seem satisfied if a witness with a working familiarity with the GPS system explains how it works, how the data were collected, and what the data mean. See United States v. Espinal-Almeida, 699 F.3d 588 (1st Cir. 2012) (ruling that data taken from GPS device seized from boat used for drug trafficking were properly authenticated by the testimony of the lab analyst who examined the device; the analyst provided a “good amount of testimony about the processes employed by the GPS,” allowing the court to apply Fed. R. Evid. 901(b)(9), which permits a witness to describe a process or system and thereby authenticate the result of the process or system; the court ruled that expert testimony was not required to authenticate the data, noting that the analyst was “knowledgeable, trained, and experienced in analyzing GPS devices”).
Several cases have focused on the qualifications and experience necessary to authenticate the data. Courts generally have ruled that the witness need not be an expert so long as the witness is familiar with the technology. Id. See also United States v. Brooks, 715 F.3d 1069 (8th Cir. 2013) (a bank robber was apprehended based on a GPS device that was placed surreptitiously in the loot bag; the trial judge properly took judicial notice of the “accuracy and reliability of GPS technology” generally, and the testimony of an employee of the security company that supplied the device was sufficient to admit the data generated by the device in question; although the witness apparently lacked a “scientific background,” he had worked for the company for 18 years, “had been trained by the company . . . knew how the device worked, and . . . had demonstrated the device for customers dozens of times”); United States v. Thompson, 393 Fed. Appx. 852 (3d Cir. 2010) (unpublished) (a bank robber was apprehended based on a GPS device that was placed surreptitiously in the loot bag; the GPS data was authenticated at trial by an employee of the security company that supplied the device; he explained how the device worked, and he was properly permitted to testify as a lay witness rather than an expert given that his knowledge was based on his personal experience with such devices).
I’m interested in readers’ thoughts about this issue and experiences with different kinds of witnesses used to authenticate GPS data.
More and more criminal cases involve electronic tracking. Sometimes the defendant is tracked using GPS, other times using cell site location information. Either way, interesting evidentiary questions arise. May an officer who knows how to use a tracking device testify about tracking, even if she doesn’t know much about how the underlying technology works? Who can testify about cellular towers and how cellular telephones connect to them? Is such testimony lay witness testimony or expert testimony?
GPS tracking. The recent case of State v. Jackson, __ N.C. App. __, 748 S.E.2d 50 (2013), provides helpful guidance regarding GPS tracking. The defendant in that case sexually assaulted a woman on the street. He was wearing an ankle bracelet, apparently as a condition of pretrial release on other charges. At trial, the supervisor of the Charlotte-Mecklenburg Police Department’s electronic monitoring unit testified about the ankle bracelet and introduced a video tracking the defendant’s movements during the time period in question. On appeal, the defendant contended that “the State failed to establish a proper foundation to verify the authenticity and trustworthiness of the data” and needed to verify the accuracy of the data before it could be admitted, but the court ruled that the officer’s “testimony established a sufficient foundation of trustworthiness.” The court also stated that the officer’s testimony was admissible as lay witness testimony based on his review of the tracking data, rather than as expert testimony. Both the fact that the court approved of testimony from an officer – rather than a scientist or an engineer – and the fact that the court deemed the testimony lay testimony are significant.
As an aside, Jackson makes an interesting contrast to State v. Meadows, 201 N.C. App. 707 (2010), where the court of appeals ruled that an officer could not testify as an expert regarding the use of the NarTest machine to identify controlled substances, because there was insufficient evidence of the machine’s reliability and the officer had no training in chemistry to allow him to assess the functioning of the machine.
Cell site tracking. I’m not aware of a North Carolina appellate case addressing the evidence issues surrounding cell site tracking testimony. However, there are some relevant cases from appellate courts around the country. Some cases involve officer witnesses, while others involve witness from telecommunications service providers. Let’s look at those cases separately.
Testimony by officers. Several courts have allowed officers to testify as lay witnesses regarding at least basic cell site tracking procedures. See, e.g., United States v. Feliciano, 300 Fed. Appx. 795 (11th Cir. 2008) (unpublished) (holding that a trial judge did not abuse his discretion in allowing an officer to testify “about cell tower sites”; the officer “simply reviewed the cellular telephone records . . . which identified cellular towers for each call, and based on his personal knowledge concerning the locations of certain cellular towers, testified that, at the time of the call [a specific phone was not near a specific location]”); United States v. Evans, 892 F.Supp.2d 949 (N.D. Ill. 2012) (holding that an officer would be allowed to testify as a lay witness regarding the location of cell towers and regarding which towers the defendant’s cell phone used at what time, and that the officer would be allowed to plot the towers on a map without qualifying as an expert; however, any testimony about how cellular networks work and “granulization theory” would require qualification as an expert). On the other hand, Wilder v. State, 991 A.2d 172 (Md. Ct. App. 2010), ruled that “the use of cell phone site location evidence and the accompanying testimony of a law enforcement officer who explain[s] its use require the qualification of the sponsoring witness as an expert.” It seems to me that the more technical and complicated the tracking procedure is, the more likely a court would be to require an officer to qualify as an expert in order to testify about it.
Testimony by employees of telecommunications service providers. Courts have also considered testimony from employees of cellular service providers. Most courts seem to have allowed relatively low-level employees to testify as lay witnesses about cell site tracking. See, e.g., Gosciminski v. State, __ So.3d __, 2013 WL 5313183 (Fla. Sept. 12, 2013) (a Nextel engineer testified during a murder case regarding “maps of the cell towers, the coverage areas of the towers, propagation information, and specific cell phone calls made or received by [the defendant]” and introduced diagrams regarding tower locations and sector information; this was properly admitted and did not require that the engineer be qualified as an expert because “such information is understood by the average juror who owns a cell phone”); Woodward v. State, __ So.3d __, 2011 WL 6278294 (Ala. Ct. Crim. App. Dec. 16, 2011) (lay witnesses employed by cell phone company were properly allowed to testify that cell phone records “indicated the locations of the callers at certain times”; the testimony did not require specialized knowledge and was limited to information regarding “cell towers used during certain phone calls”); Malone v. State, 73 So.3d 1197 (Miss. Ct. App. 2011) (cell phone company employees properly testified as lay witnesses regarding cell phone records, tower locations, tower coverage information, and tower usage; none of this was “so complex or technical as to render it expert testimony”). Again, the more complex the testimony is, the stronger the argument for requiring the witness to qualify as an expert.
Conclusion. The evidence issues surrounding tracking technology may prove difficult to settle. In part, this is because tracking technology itself changes so rapidly that decisional law struggles to keep up. But it is also because the line dividing lay and expert testimony is unstable. A witness must testify as an expert if the witness’s testimony involves “scientific, technical or other specialized knowledge,” N.C. R. Evid. 702, that is beyond the experience of a typical juror. But a typical juror today knows far more about GPS satellites and cellular towers than a typical juror a decade ago. And of course, tomorrow’s jurors likely will know even more.
Yesterday, the United States Supreme Court decided United States v. Jones, the important GPS tracking case I previously blogged about here. (The case was captioned United States v. Maynard at that time.)
In brief, Washington, DC officers suspected that the defendant was a drug dealer. They wanted to track his movements, so they obtained a search warrant that allowed them to install and monitor a GPS tracking device on a Jeep owned by the defendant’s wife but driven exclusively by the defendant. However, while the warrant authorized installation of the device in DC within 10 days, the officers didn’t complete the installation until the 11th day, in Maryland. They then tracked the defendant for 28 days. Among other things, they determined that he had visited a stash house in which the officers ultimately found large quantities of money and cocaine.
Facing drug charges, the defendant moved to suppress the tracking data. Because the officers had failed to comply with the terms of the warrant, the district court treated the officers’ conduct as being warrantless activity. (All subsequent courts followed suit on this point.) Nonetheless, it mostly denied the defendant’s motion, concluding that the defendant had no reasonable expectation of privacy in his travels on the public roads, and therefore, that the officers’ conduct was not a “search” for Fourth Amendment purposes. The government introduced the tracking data at trial and the defendant was ultimately convicted.
He appealed. The DC Circuit reversed, holding that prolonged GPS monitoring is a Fourth Amendment search. Distinguishing United States v. Knotts, 460 U.S. 276 (1983), which held that the short-term use of electronic “beepers” to track a suspect’s movements on the public roads did not intrude upon a reasonable expectation of privacy, the court wrote that “no single journey reveals the habits and patterns that mark the distinction between a day in the life and a way of life . . . . Prolonged surveillance reveals types of information not revealed by short-term surveillance, such as what a person does repeatedly, what he does not do, and what he does ensemble.”
Some commentators called this the “mosaic theory” of the Fourth Amendment. Critics wondered how an accumulation of things that were not themselves searches could sum up to a search, and wondered how to draw the line between permissible warrantless short-term monitoring and improper warrantless long-term monitoring.
The government petitioned for certiorari, and the Supreme Court took the case. It affirmed the court of appeals. Justice Scalia wrote the majority opinion, which holds that “the Government’s installation of a GPS device on a target’s vehicle, and its use of that device to monitor the vehicle’s movements, constitutes a ‘search.’” However, the majority’s reasoning differs substantially from that endorsed by the DC Circuit. According to Justice Scalia, the key to the case is that “[t]he Government physically occupied private property for the purpose of obtaining information.” That is, the government trespassed when it undertook the “physical intrusion” of installing the device. And a trespass “conjoined with . . . an attempt to find something or to obtain information” constitutes a search for Fourth Amendment purposes. Indeed, according to Justice Scalia, such an intrusion onto private property for the purpose of gathering information was exactly the type of conduct the Framers of the Fourth Amendment intended to prevent.
This emphasis on trespass has roots in the Court’s precedents. As Justice Scalia notes, “our Fourth Amendment jurisprudence was tied to common-law trespass, at least until the latter half of the 20th century.” However, in recent years, the Court has analyzed virtually all Fourth Amendment cases under the “reasonable expectation of privacy” rubric first enunciated in Justice Harlan’s concurrence in Katz v. United States, 389 U. S. 347 (1967). The majority does not repudiate that test – indeed, it explicitly reaffirms that governmental conduct that intrudes upon such an expectation is a search – but finds that the trespass analysis survives Katz as an alternative way of establishing that officers are undertaking a search regulated by the Fourth Amendment. And because the majority resolves the case under the trespass analysis, it declines to reach the issue of whether GPS tracking is a search under the expectation of privacy analysis.
Justice Alito concurred in the judgment, and wrote an opinion joined by three other Justices. His opinion argues that the expectation of privacy analysis in Katz supplanted, rather than supplemented, the trespass approach to the Fourth Amendment. In support of this claim, the opinion quotes several excerpts from Katz and later cases to the effect that a physical trespass is neither necessary nor sufficient to establish a Fourth Amendment violation. Thus, Justice Alito views Justice Scalia’s emphasis on the law of trespass as archaic and unhelpful. Analyzing the matter exclusively under the expectation of privacy test, Justice Alito finds that the officers’ conduct amounted to a search essentially for the reasons given by the court of appeals: “[R]elatively short-term monitoring of a person’s movements on public streets accords with expectations of privacy that our society has recognized as reasonable. . . . But the use of longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy.”
Justice Sotomayor joined Justice Scalia’s majority opinion, but wrote a separate concurrence that strikes me as very important. She agreed that the case was properly resolved under the trespass analysis. But she plainly indicated that she would also have found a Fourth Amendment search even absent a trespass. That is to say, she “agree[d] with Justice Alito that, at the very least, ‘longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy.’” That’s significant because it means that there are five votes – Justice Sotomayor plus the four Justices who signed Justice Alito’s opinion – for the view that prolonged GPS tracking is a search even if it can be done without a trespass, for example, by concealing a tracking device inside an object and then convincing the suspect to accept the object into his vehicle, or perhaps by using a vehicle’s built-in GPS system. (Justice Sotomayor also suggested that even short-term GPS tracking might be a search, and that the Court should reconsider the doctrine that a suspect’s disclosure of information to a third party destroys his expectation of privacy in that information vis-à-vis the police, though no other Justice joined her in expressing those sentiments.)
Newspaper coverage of the case is here. Orin Kerr, a leading scholar in this area whose article was cited by both the majority and the principal concurrence, has been posting like crazy at the Volokh Conspiracy. Rather than link to his many posts individually, I’ll just link to the front page of the blog and you can scroll through. I may have more thoughts about this case later, and if so I will do a follow-up post. Stay tuned.
I’ve had several questions lately about the authority of law enforcement to track a suspect by obtaining information about contacts between the suspect’s cellular telephone and cellular towers. I’m also going to be teaching about some related issues in the near future. So I’ve prepared a short summary of the law in this area, which I’m making available here as a PDF. I’ve watermarked the document “draft” because I reserve the right to tinker with it some more, so if you read it and have comments, criticisms, or suggestions, please let me know. That said, I believe the summary is accurate as is. I hope it’s helpful.