Educational Feature: April 2000 {Prepared by John W. Ellis, B.S., M.A.J.}
Investigative Use of the Global Positioning System

Recently, an investigator in an on-line forum asked a question about using G.P.S. for investigative purposes. This seemed like a good topic to address this month. So, for those of you who have no experience with the system, its background or investigative use, here is a short run-down of this developing civilian investigative field.

The Global Positioning System (G.P.S.) was originally developed by the United States Department of Defense to assist military forces. The system is a series of orbiting satellites with various onboard electronic systems and ground control stations for the satellites. The various satellites transmit radio signals which can be received by programmed G.P.S. units that are hand-carried or mounted in a variety of vehicles, aircraft, missiles, etc. Since its original military inception, the system has been expanded (enhanced G.P.S.) and portions also made available to both the civilian commercial sector and the international community. Congress clearly has directed this in 10 U.S.C. 2281 and 42 U.S.C. 14712. These sections of the federal code recognize commercial applications and task the Department of Defense, Department of Transportation and Department of Commerce with specific responsibilities. Consequently, basic use of this government resource is lawful for commercial purposes, including lawful investigations. Before covering how to determine the lawfulness of G.P.S. investigations, lets examine the general capabilities and limitations of G.P.S..

Commercial G.P.S. units are basically radio receivers; consequently, it must have a line-of-sight to the satellites in order to receive the radio signal. Any obstruction will limit its effectiveness or reliability. The first obstruction is the earth. The satellites are in orbit around the planet so their availability varies at different times of the day in different areas of the world. Some are never visible at specific locations. A satellite that is overhead is said to be ‘above the horizon'; the number of satellites above the horizon at a specific location and times affects the reliability of the G.P.S. location reading. Obstructions, however, do not end with the horizon. Mountains, tunnels, tall buildings, overhead parking levels, car bodies or even dense cargo in a truck bed can all block the radio signal or at least reduce its strength. If the G.P.S. unit can't receive signals, it can not determine the position. G.P.S. receivers must receive at least two signals to perform any computation of position with three generally being considered the minimum for accurate computation. The more satellite signals being received, the greater the level of reliability of the position computation.

G.P.S. receivers are preprogrammed with certain information about the satellites and the geographic area. Less expensive units are designed to operate in a limited area such as North America while more expensive units can operate worldwide. The expensive G.P.S. units require user input concerning the continent or general geographic area before they can operate. The user instruction manual contains this basic information. Using this basic locational data, the G.P.S. unit identifies the satellite signals and searches the internal database to compute a position both horizontally and vertically. With good signal strength and good internal data, G.P.S. units are capable of displaying the location to the nearest meter. This is then displayed in longitude and latitude or in either civilian or military map coordinates. If the internal database also contains a mapping program, the display can be overlaid on a street or terrain map. The limitations here, of course, are the amount, type and accuracy of the internal database and the quality of the associated electronics and internal or external antennas. Where user programming is required, the output is also dependent upon the user skill.

As an electronic unit, G.P.S. receivers are limited by the power source. Twelve volt power sources obviously place a detectable power load on a vehicle's battery while internal batteries vary in quality and duration of operation. Environmental conditions such as heat, humidity, etc. can limit the operation of the unit. Obviously, the more rugged the unit, the greater its reliability and its usual expense. At this point, we have identified the limitations as: Line of sight obstructions, internal database programming, user programming, power source, and electronic component reliability. Investigative use may also impose size or stealth limitations, unusual antenna requirements to overcome obstruction limitations, and cost/loss risk limitations on the equipment use. Once it is emplaced, it could be gone permanently.

Investigative use of G.P.S. begins with the legal considerations. Under 42 U.S.C. 14712 Promotion of the United States Global Positioning System, G.P.S. is clearly identified as accessible to the general public for commercial purposes. So usage of the basic G.P.S. services is clearly lawful under this statute, but does it constitute an ‘interception' under the federal wiretapping statutes? The answer is ‘no' under most, but not all, circumstances. The three keys to interpreting lawfulness are the legal definition of the G.P.S. itself, the communication or recording device that it uses, and the reasonable expectation of privacy in the circumstances of its use.

Under 18 U.S.C. 3117(b), G.P.S. units can qualify as a ‘tracking device' which is defined as "an electronic or mechanical device which permits the tracking or movement of a person or object." Since G.P.S. records a location, it can qualify, but only when it records or transmits more than one sequential location over a period of time. A single instance of its use probably would not qualify since there is no movement. This classification is important since the federal wiretapping statute excludes tracking devices under it definition of ‘electronic communications', the next consideration.

Under 18 U.S.C. 2510, an ‘electronic communication' includes radio signals and electromagnetic recording systems, and specifically excludes tracking devices. The statute does require that the signal is transferred and also includes an interstate commerce clause. So while basic G.P.S. units qualify as electronic devices that receive signals ‘readily accessible to the general public'[18 U.S.C. 2510(16)], they do not become ‘electronic communication devices' until they transfer the radio signals received. You could argue that this occurs when it displays the position on its included screen, but this argument is somewhat weak, particularly with the included exclusion of tracking devices. It clearly qualifies as an electronic communication device when it records the output to a chip, disk or tape or when it transmits the output via a radio signal, but since tracking devices are specifically excluded under the same statute, any court would likely look at other considerations. At this point in the process, you apply a two part test, does the movement recorded affect interstate commerce and does the electronic signal utilize a common carrier as defined under the wiretapping statute? If both answers are yes, then the G.P.S. activity is illegal. If the conduct (movement involved) is only personal, then the transmitted signal does not violate the wiretapping statute even if it uses a common carrier (assuming that it transfers only electronic location information and not voice communication). It may, however, violate other statutes pertaining to the right to privacy.

Under KSA 21-4001 Eavesdropping, "Entering into a private place with intent ... to observe the personal conduct of any person or persons therein" constitutes a criminal misdemeanor. The statutory definition of a private place uses the reasonable expectation of privacy test and specifically excludes a place to which the public has lawful access. Further, the federal court in US vs Knotts 460 US 276 (1983) ruled that use of a tracking device on public streets was lawful. This would seem to clear the way for use of G.P.S. devices on vehicles in Kansas, but there is a limitation that many investigators would not immediately see. As long as the vehicle is on public streets or publicly-accessible areas such as driveways or parking garages, everything is okay. But, if the vehicle on which the G.P.S. unit is installed pulls into the garage of a private residence, it has now entered into ‘a private place' and the G.P.S. recording or transmission is now unlawful under the Kansas statute. The same problem may also occur when a vehicle enters a third-party business such as a warehouse, repair facility, gated loading area, etc.

So when can you legally use G.P.S. units for investigative purposes in Kansas?

As you can see, G.P.S. is not the magic bullet some advertisers claim and many investigators believe it to be. There is no replacement for investigative expertise. Those who rushed out and purchased one to solve all of your problems, please contact me. I have an exclusive distributorship on ‘10-ring' bullets. Guaranteed to hit! Low, Low Prices! My bank account needs you! Buy now!