It's already public: why federal officers should not need warrants to use GPS vehicle tracking devices.

• Author: Ganz, John S.
• Position: Global Positioning System

1. INTRODUCTION

   A technology previously associated with military "smart bombs" now offers police proven, substantial value in investigating the movements of criminal suspects. Global Positioning System (GPS)-based surveillance systems enable police to cheaply and easily gather intelligence and evidence they would otherwise have to obtain through more costly, cumbersome and risky means such as physical "tails" by pursuing officers. (1) The efficiency gains GPS tracking provides are especially significant because they enable police to extend their operational capability with minimal incremental spending. (2)

   In a recent case in Washington State, police used GPS trackers attached to a murder suspect's car and truck to quickly locate the remote wilderness grave in which the suspect had buried the body of his nine-year-old victim. (3) The information proved critical to prosecutors in obtaining a conviction. (4)

   While the use of GPS tracking devices grows among law enforcement, federal law remains largely undefined regarding the need to obtain warrants before their deployment. State law presents a similarly mixed picture: while California and Nevada courts ruled that no warrants are required before using GPS devices, (5) the Washington Supreme Court (6) and a county court in New York (7) recently ruled that police must obtain warrants before conducting GPS-based surveillance. These rulings followed a 1988 Oregon State Supreme Court ruling requiring state police officers to obtain warrants before using "beeper" transmitters, the technological precursors to GPS. (8)

   The federal-state split is a function of differing constitutional conceptions of personal privacy. (9) Federal courts have not required police to get warrants to use electronic tracking devices because the information gathered through them--such as the movement of a car or airplane through public thoroughfares--is already publicly available. Put another way, federal law recognizes no legitimate expectation of privacy with respect to movement in public. (10) This notion is especially true for cars, which federal courts grant even less protection with respect to search and seizure. (11)

   More recently, some state courts and groups such as the American Civil Liberties Union (ACLU) cited the level and precision of information GPS trackers collect relative to beepers in arguing that their use should be subject to a warrant requirement. (12) These groups conceive of GPS as a substitute police officer who gathers and stores precise, detailed data which goes well beyond that available through less sophisticated tracking devices. (13) As such, these parties consider GPS substantially more intrusive than beepers and therefore worthy of heightened procedural restraints.

   These arguments have succeeded at the state level because state law privacy protections often exceed those provided under federal law. (14) While federal law merely prohibits unreasonable searches and seizures in limited situations, several state constitutions, like those of Oregon and Washington, adopt a broader conception of privacy which includes protection against government scrutiny. (15) Absent warrants, state and local law enforcement agencies operating under these more far-reaching constitutions can neither invade a protected space nor engage in systematic forms of scrutiny, such as deployment of GPS trackers. (16)

   This Comment provides a legal argument (17) that GPS-based tracking of vehicles in public areas does not implicate the Fourth Amendment and therefore should not be subject to warrant requirements--provided such tracking does not pierce the exterior of a vehicle or enable police to track movement inside a legitimately private space. To the extent a state constitution is consistent with federal law, that state should follow this approach. Fundamentally, the information that law enforcement obtains through GPS tracking is already available, either without technological assistance or with less sophisticated tracking technology. As such, it is legally insignificant in terms of current Fourth Amendment jurisprudence.

   This clarification is critical because GPS technology offers substantial promise in improving the quality of evidence available to law enforcement. (18) The fact that GPS provides a new form of technical evidence--similar to video surveillance or audiotape of conversations-argues in favor of encouraging its use because judges and juries could, at least theoretically, rely more comfortably upon it than they would less reliable information, such as witness testimony. Moreover, by overlaying GPS tracks with other electronic intelligence such as recorded phone conversations, police develop a richer, more accurate understanding of their targets, one which can aid juries in deciding a case. (19)

   From a policy perspective, the practical limits of resources available to law enforcement in the post-9/11 era argue in favor of GPS usage because the technology greatly enhances law enforcement efficiency. (20) And while critics argue GPS represents a danger to individual liberty, the technology can just as easily be used to attack public corruption: officials in New Jersey, for instance, used GPS tracking to prosecute police officers charged with falsifying records and other forms of misconduct. (21)

   Part II explains the technological basics of tracking technology and possible law enforcement uses of GPS.

   Part III first examines the federal constitutional law of search and seizure relevant to the installation and monitoring of electronic tracking devices. It then examines recent developments in state law.

   Part IV argues the case for continued, warrantless use of GPS-based devices to track suspect vehicles traveling in public, at least on the federal level. Additionally, this Part argues that the same principles should apply on the state level when state constitutions provide limited privacy protections similar to those in the United States Constitution.

2. BACKGROUND

   1. TECHNOLOGIES IN QUESTION, CAPABILITIES AND LIMITS

      Two major tracking technologies are available to police: beepers, or "bird dogs," and GPS trackers.

      1. Beepers

         "A beeper is a radio transmitter, usually battery operated, which emits periodic signals that can be picked up by a radio receiver." (22) Once the beeper is placed on the target item, a police officer uses a receiver to track the location of the beeper by determining its position relative to his. Officers then maneuver into a position where the target item can be followed and/or sighted.

         Beepers are passive--they neither collect nor store data. Rather, they simply emit electronic pulses which can be picked up and followed. Their value thus depends on the ability of monitoring officers to physically maneuver and locate the object in question. In contrast, GPS devices independently acquire and store data which is substantial and precise.

      2. GPS

         GPS is a network of at least twenty-four satellites which continuously send radio signals transmitting their locations; receivers on earth triangulate their own three-dimensional position using information from at least four of the satellites. (23) The position "fix" a receiver creates consists of current longitude, latitude, and time. (24)

         Fixes, when recorded, become a track, or chronological record, of travel. (25) A typical track is accurate up to fifteen feet and two miles per hour of speed, but tracks can be adjusted to record position more frequently, giving a more detailed representation of the target's path. (26)

         The memory in many GPS units is designed to hold only a fraction of the information that the GPS [device] actually possesses. Accordingly, a user must download GPS track ... information, either by physical connection to a computer or with a GPS transceiver, a radio, or a cell phone connection. Even inexpensive commercially available software and a small personal computer can extract speed, exact position, distance traveled, and travel times, and can overlay the traveled track on maps or aerial photographs ... available on the Internet. (27) Most GPS tracking devices are "about the size of a paperback book and can be affixed to a car's undercarriage with a magnet. Manufacturers say ... [their] cost--about $1,000--is headed down as the market" for the devices expands. (28) Police agencies say these systems pay off because "it costs more to keep a team of officers on a suspect's trail than [it does] to download information from a computer." (29)

         One model, which a Law Enforcement Technology Magazine reviewer called a "vehicle tracking system that would make James Bond envious," sells for $2,396 per unit. (30) Users pay $59 per month of tracking data used. (31) The product can be attached to a car in thirty seconds and operates anywhere in the United States, Canada, and Mexico where cell towers exist. (32)

         GPS tracking is precise but not foolproof. In the Scott Peterson murder case, for instance, trackers attached to motor vehicles Peterson used at times showed him traveling at 38,000 miles per hour (33) and at 489 miles per hour. (34) In addition, a device placed in Peterson's deceased wife's car, which he drove, did not work for a three-week period. (35) Carports, tunnels, and parking structures can block a tracker's GPS signal. (36) Finally, after downloading to a computer, GPS tracks "are no different from any other data file--they can be manipulated (like a sound recording), corrupted, or accidentally erased." (37)

   2. USE OF GPS IN CRIMINAL INVESTIGATIONS

      Law enforcement agencies use GPS in a variety of situations, including:

      MURDER INVESTIGATIONS: In the Scott Peterson case, mentioned above, GPS tracks showed suspect Peterson made at least five visits in January 2003 to the Berkeley, California marina near the place where his victims washed up. (38) Peterson's visits suggested "a pattern of a criminal returning to a crime scene." (39)

      In Washington State, a GPS track from a device placed on a...