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 3rd 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 3rd 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?