Can GPS be used to track your movements, without a warrant? That depends...

The 4^th Amendment implications of location-based data have been a topic of active discussion, prompted in part by two recent federal Circuit Court rulings, and to a lesser degree by some outspoken opinions made both in concurrence and dissent to these and other court rulings, and a number of legal interpretations offered by law professors (including some who filed briefs in the cases in question) and other analysts about the most appropriate interpretation of the text of the 4^th Amendment itself. These opinions add to ongoing discussions of several laws addressing law enforcement and government behavior with respect to 4^th Amendment searches and seizures, and analyses of both legislative intent and judicial reasoning when trying to apply these constraints to relatively recent technologies like GPS that weren't considered when the laws or legal precedents were established. The divergence of several federal Circuit Courts on matters central to this debate raises the likelihood that the Supreme Court will need to weigh in on the issues, although it is entirely possible that a case that makes it to that level will involve cell phone tower location information or other data collected in the course of modern provision of telecommunications services, and not GPS data per se.

In August, the D.C. Circuit reversed the conviction of an alleged drug trafficker on the grounds that the installation and monitoring of a GPS tracking device — placed on the man's vehicle without a warrant — over a continuous four-week period constituted a search and violated the suspect's reasonable expectation of privacy. This ruling ran counter to opinions from multiple other federal courts involving investigatory vehicle tracking without a warrant, all of which rely on the Supreme Court's ruling in United States v. Knotts, which said that using a tracking device to monitor travel on public roads is no different than visual surveillance and therefore did not require a warrant. While this D.C. Circuit case is notable primarily for its departure from the Knotts precedent, the facts of the case place the issues the court addressed within some narrowly defined situational boundaries that leave many key 4th Amendment questions unanswered. Specifically, the GPS device used in the investigation was affixed to the bumper of the defendant's car, and transmitted location data directly to law enforcement personnel. This meant that the GPS location data did not extend inside any buildings or particular locations (especially the defendant's home), and there was absolutely no question (as there is in analogous investigations involving location data from cellular telephones) as to whether the GPS device in question should be considered a tracking device.

In a case with somewhat different facts but which raises many of the same key issues, the 3^rd Circuit filed a ruling last week regarding an ex parte application by the government seeking to obtain cell site location data about a cell phone subscriber from the subscriber's wireless service provider. The government in this instance sought access to historical cellular phone location information from the service provider under the terms of the Stored Communications Act (specifically, 18 U.S.C. §2703(d)), a legal standard which enables investigators to compel disclosure of subscriber records without obtaining a warrant. The magistrate judge who considered the government's original request denied the request, but upon appeal the 3^rd Circuit vacated the magistrate judge's decision and remanded the government's application for reconsideration by the magistrate court, with instructions to follow the opinions expressed in the Circuit panel's ruling, which in essence rejected the original reasoning used by the magistrate judge to deny the government's application. Among the questions considered in this appeal were whether the use of cell tower location information should equate to the cellular telephone being categorized as a tracking device, and whether wireless subscribers can have a reasonable expectation of privacy with respect to such location information. In direct contrast to Maynard, in this case there was no GPS data involved (although the government gives every indication that it believes it could seek GPS location data in the same manner) and the location data was collected by the service provider in the course of normal operations, not by the investigators. Consistent between the two cases are that the data in question covers an extended period of time, and at least according to the government's contention (technical accuracy of the claim notwithstanding), the specificity of the location data is not such that it would unquestionably extend within the confines of a subscriber's home.

Looking at several former and recent federal court rulings in the aggregate, whether or not GPS location information can be acquired and used by law enforcement depends on several factors. To determine whether getting access to GPS data about an individual without a warrant is constitutional, you have to consider several key questions:

• Is the collection and use of GPS data a search?
• What sort of GPS device is in use?
• Who is collecting the GPS data?
• In what locations is the individual when GPS data is collected?
• What type of data is being sought?
• What period of time does the GPS data cover?

Only the Maynard ruling (so far) has directly addressed the use of GPS tracking devices, and in that case the device was physically placed on a vehicle. A more interesting question would be how the laws and court precedents are interpreted when the government seeks GPS data transmitted by cellular telephones. In such a hypothetical instance it's hard to imagine a credible argument against considering a cellular phone to be a tracking device (the 3rd Circuit accepted the government's argument in this regard when cell site location data was involved), so it would seem that §2703(d) requests could not be used. However, in the Justice Department's own guidelines on obtaining electronic evidence for investigations, it lists GPS data among the many "record" contents that it advises its personnel may be sought using applications under §2703(d). Given the immediate impact the D.C. Circuit Court's Maynard opinion has had among members of the judiciary at all levels, and the divergence of opinions among multiple federal circuits, it would seem the Supreme Court would not only be willing to weigh in on these issues, but might even be eager to do so.