In re the Admissibility of Motor Vehicle Speed Readings
In re the Admissibility of Motor Vehicle Speed Readings
Opinion of the Court
This proceeding involves the reliability of a device known as the LTI Marksman 20-20 Laser Speed Detection System manufactured by Laser Technology, Inc. For ease of expression, I shall hereafter usually refer to this device as the “laser speed detector” or the “detector”. The New Jersey State Police have recently purchased 23 of the detectors and have begun to deploy them in their motor vehicle law enforcement operations. More particularly, a number of the detectors have been used along Interstate Route 80 in the Township of Rockaway and in the Township of Parsippany-Troy Hills in Morris County and numerous speeding tickets have been issued based upon readings produced by the detectors.
Because the laser speed detector has only recently been put into use in New Jersey, its reliability in establishing the speed of a motor vehicle has not been adjudicated in any New Jersey court. A number of defendants in speeding violation cases pending in the Municipal Court of Rockaway Township and in the Municipal Court of Parsippany-Troy Hills Township have filed motions challenging the admissibility of speed readings produced by the
The laser speed detector is a compact, hand-held device which is covered by United States Patent Number 5,359,404. The patent gives the following summary of the invention embodied in the laser speed detector:
The invention comprises a laser speed detector comprising a laser rangefinder, a sighting scope for a user to visually select a target with an operably-disposed trigger for triggering operation of the detector upon the selected target, and a microprocessor-based microcontroller which is eontrollingly and communicatively interconnected to the laser rangefinder. In a highly preferred embodiment, the instrument is small enough to be easily hand-held.
The laser rangefinder, under the supervision of the controller, fires a series of laser pulses at a selected remote target at known time intervals, and detects reflected laser light from each pulse. Preferably, the pulses are fired at equally-spaced intervals. The laser rangefinder further determines count data reflective of the*214 time-of-flight of each pulse to the target and back, and provides these data to the control means. These count data comprise the respective arrival times of a REF (reference) pulse representing the firing time of the laser pulse, and an RX pulse representing reflected laser pulse light.
The microcontroller is configured to read these count values and to compute from them, the time-of-flight of the laser pulse and in turn, the distance to the target. The controller then computes the velocity of the target relative to the speed detector from the change in distance to the target divided by the known elapsed time between firing of the pulses.
The laser rangefinder has several notable features which provide significant improvement in accuracy and reliability (not necessarily listed in order of importance). First, a crystal clock-based timing analysis circuit including a gating circuit which is a digital logic, edge-sensitive gate for which both the “opening” and the “closing” of the time window can be selectably set by the microcontroller. In a preferred embodiment, the microcontroller is configured to alternately widen and narrow the window to selectively lock on “true” RX pulses and exclude pulses due to noise or other factors.
Second, the timing analysis circuitry is constructed to generate self-calibration pulses and to process them in the same manner as the REF and RX pulses, thereby producing a set of calibration interpolation counts. The controller uses these calibration interpolation counts along with the REF and RX interpolation counts to compute self-calibrated values of the respective fractional portions of the clock periods at which the REF and RX pulses arrived. The self-calibration pulses comprise a pair of pulses, referred to for simplicity as TMIN and TMAX, which differ by a known integral number of clock periods (with neither TMIN nor TMAX being zero). Together, TMAX and TMAX define an expanded interpolation interval -within which the fractional portions of the RX and REF arrival times are interpolated. This self-calibrating interpolation provides greatly enhanced resolution and accuracy of distance measurements based on elapsed time.
Third, the laser rangefinder has a first collimator which directs a major portion of an outgoing laser pulse toward the selected target, and a second collimator which redirects a minor portion of the laser pulse to produce a timing reference signal. In one embodiment, the minor portion of the laser pulse is sent to a second light detector separate from a first light detector (here embodied as a silicon avalanche photodiode detector or “APD”) which focusses and receives reflected laser light. Alternatively, the minor portion of the laser pulse is sent to the same detector which detects the returned laser light.
Dr. Daniel Y. Gezari, an astro-physicist who has been employed at the National Aeronautics and Space Administration Space Flight Center for the past 18 years, testified with respect to the general scientific concepts involved in the use of lasers to measure distance and, derivatively, speed. Lasers have been used as a standard tool for the measurement of distances by astro-physicists and other space scientists for a number of years. Mr. Jeremy
A laser is an artificially generated and amplified light which is in the infrared light section of the electromagnetic wave spectrum. It is not visible to the naked eye. It is very concentrated. The laser speed detector fires a series of laser pulses at a selected remote target. When the laser light strikes the target, a portion of the light is reflected back to the detector. Since the speed of light is a known constant, by measuring the time which it takes for the laser pulse to travel to the target and back, the detector is able to calculate the distance between the detector and the target. Each laser pulse which is fired and reflected back establishes one distance reading. The laser speed detector fires 43 laser pulses every time the trigger on the. detector is squeezed. These 43 pulses are fired in a total period of approximately one-third of a second. If the target at which the laser pulses are fired is a stationary target, each of the 43 pulses will give the same distance reading to the target, and distance will be the only thing that the detector can tell us about the target. However, if the target is moving, each of the 43 pulses will give a slightly different distance reading and the detector can then compute the velocity or speed of the target from the changes in distance divided by the known elapsed time between the firing of each of the laser pulses. In
There are, however, both conceptual and practical problems which have to be overcome in designing and constructing a reliable laser speed detector. The detector works by measuring the time it takes a laser pulse which it transmits to go out to a target and come back. However, there are many other pulses in the environment of the detector which can interact upon it, and the detector must be programmed to distinguish between those “false” pulses and the “true” pulses which it has transmitted.
As mentioned above, the laser is very concentrated and has a characteristically narrow beam. At a point 1,000 feet away from the detector, a laser beam is about three to three and one-half feet wide and has a height of about three feet. This may be contrasted with the beam of radar which is about 820 feet wide at a point 1,000 feet away from the radar transmitter. Although the laser beam is much more concentrated than the radar beam, it is far from being a true pinpoint. As the three by three and one-half foot laser beam strikes the very irregular surface of a moving motor vehicle, it does not hit a single, highly-reflective point on the vehicle. In effect, it splashes over a portion of the vehicle. This is true even though operators are trained to fire at the front license plate area of the vehicle, because the beam is considerably larger than the license plate. Indeed, depending upon the angle at which the beam hits a vehicle, and depending upon the vehicle’s location with respect to other vehicles on the highway, particularly a multi-lane highway, it is conceivable that a portion of the beam splashes onto another vehicle. For reasons which will become apparent when I discuss possible sweep error, there is a sense in which it is important for the detector to be programmed so that it can distinguish the point on a vehicle from which the return impulse is coming.
It is important for the laser detection device to measure distances between it and a motor vehicle at the same point on the
The inventor of the laser speed detector is clearly aware of many of the conceptual and practical problems involved and has designed computer programs and hardware mechanisms designed to trap a variety of errors. The State’s expert, Dr. Gezari, submitted a report which had this to say on the subject of error trapping:
*218 One of the basic operating features of the LTI 20-20 is an error trapping algorithm which tests the integrity of the received data. Thirty to forty data pulses received must have the correct pulse shape, rise time, duration, color and basic time sequence to be considered valid data fit for analysis. If at least thirty received impulses do not fit the criteria the data is rejected and no velocity is calculated. Other criteria are also used by the manufacturer to identify valid pulses having to do with actual vehicle characteristics — acceleration/deceleration parameters, change in target direction, etc. The LTI 20-20 speed gun will display error messages if no velocity is calculated informing the operator as to the reason no answer was given or no velocity was calculated. These error messages do not indicate errors were made; they simply identify the reason that no calculation was made. The error trapping approach used in data analysis further insures that factors such as steadiness of the gun during the measurement, weather conditions, motion of other objects nearby, etc. do not affect the accuracy of the speed reading calculated.
The electrocomputer circuitry of the LTI 20-20 speed gun uses sophisticated techniques including pulse stretching algorithm, statistical data analysis techniques, etc. to provide fully adequate timing accuracy in the generation and detection of laser pulses resulting in typical velocity measurement accuracies of ± 1 mile per hour or better for typical highway speed measurements.
The inventor and designer of the detector, also testified fairly extensively with respect to his efforts to eliminate inconsistent data and to trap error. One of the mathematical techniques to screen out inconsistent and erroneous readings is a procedure called the “average of least squares”. That procedure was discussed at some length by Mr. Dunne and by three of the defense experts, and an exhibit setting forth a partial test program for least square speed error was admitted in evidence. The average of least squares is a common procedure which can eliminate inconsistency and error in a variety of applications, but it is only a limited part of the error trapping techniques which are purportedly built into the laser speed detector.
At this point, it is important to note a very significant difficulty. That difficulty lies in the fact that Laser Technology, Inc., the manufacturer of the laser speed detector, is unwilling to disclose the details of the error trapping programs and devices built into the detector on the ground that such information is proprietary information which gives it an important competitive advantage which it should not be required to disclose. The result is that no one outside of the employ of the manufacturer knows the details of
I can understand why the manufacturer would be reluctant to disclose its proprietary information to experts retained by defendants, even under a strong and tightly drawn protective order. But, surely, techniques could be developed for disclosure to governmental agencies or to non-governmental independent testing institutions which would protect the manufacturer from any misappropriation of its intellectual property by a competitor. I note that I myself do not have the ability to analyze and evaluate the error trapping techniques involved in the detector, and I myself would not be able to do anything useful with the details of the techniques if they were disclosed to me. However, there are many experts available to government agencies and to non-governmental testing organizations who could effectively evaluate those techniques and tell us whether they appear to be adequate and have good internal logic. Under the total circumstances of this case, I have not thought it appropriate to order disclosure of the proprietary data involved. This leaves the data securely intact in terms of the proprietary interests of the manufacturer, but it also places the manufacturer in the position of losing the probative advantage of having its methodology validated by reliable experts not in the employ of the manufacturer.
Three expert witnesses testified for the defendants. They were Mr. Henry Roberts, a retired electrical engineer, Mr. Jim Coleman, an engineer who works for a defense contractor and has considerable experience with the design of electronic appliances used to measure velocity, and Mr. Paul S. Greenberg, an employee of the National Aeronautics and Space Administration who has considerable experience working with lasers to measure velocity in space applications. Each of these experts testified at considerable length with respect to a variety of conceptual and practical problems which they found with the application of laser technology
The State presented documentary evidence and testimony to the effect that the laser speed detector has been approved for use by law enforcement agencies in the United Kingdom, Sweden, Germany and Austria. It has also been approved for use by the Royal Canadian Mounted Police. The detector is being used by state and local law enforcement agencies in a fairly large number of states. In Goldstein v. State of Maryland, 339 Md. 563, 664 A.2d 375 (1995), Maryland’s highest court has approved the general concept of admitting laser speed measurements into evidence in judicial proceedings in a case in which the LTI 20-20 Laser Speed Detection System was involved. The Court of Appeals did not reach the issue of the reliability of the particular device.
The State produced a certificate issued by the Office of the New Jersey State Superintendent of Weights and Measures which reads: “This certifies that Laser Speed Detection Instrument Serial Number 008999 has been compared with standards of the State of New Jersey in possession of the State Superintendent of Weights and Measures. The error found in the time base component will result in an error of less than 0.030 MPH at any speed. Agency certified for New Jersey State Police.”
The State has also presented a final report issued by the National Highway Traffic Safety Administration of the United States Department of Transportation, issued in February, 1995, establishing “Model Minimum Performance specifications for Li-dar Speed Measurement Devices”. (The laser speed detector is a lidar speed measurement device.) The Model Minimum Performance Specifications were developed in response to a request for standards made by the International Association of Chiefs of Police. Purportedly, the laser speed detector meets the standards embodied in the Model Minimum Performance Specifications and
At first glance, the list of foreign governments which have in some way approved the laser speed detector for use by their law enforcement agencies, the list of states of the United States which have allowed the detector to be used by law enforcement agencies, the certification issued by the New Jersey Superintendent of Weights and Measures, the issuance of Model Minimum Performance Specifications by the National Highway Traffic Safety Administration and the approval of the general validity of using laser speed measurements in judicial proceedings by the Court of Appeals of Maryland appear to constitute a rather strong endorsement of the validity of the laser speed detector. However, on closer examination, the endorsements appear to be somewhat hollow in terms of using them to make a realistic assessment of the reliability of the detector. A number of American and foreign governmental agencies (or testing organizations working with them) have subjected mechanical components of the laser speed detector to limited testing and there has been some limited testing under conditions not reflective of actual highway circumstances of the detector’s ability to measure the speed of a motor vehicle which was actually being driven towards the detector. There was also very limited testing in Colorado by two state police sergeants of the laser speed detector and a similar device made by a competitor under actual highway conditions. The officers tracked the same vehicles with competing laser speed measurement devices and compared the results. Less than 100 vehicles were tracked by the officers. The competing laser speed measurement devices produced results which were roughly consistent with each other, although a few readings were widely inconsistent. The Colorado study is not particularly useful because the actual speeds of the vehicles were not known and they were not measured by any device other than the two competing laser speed measurement devices.
The Model Minimum Performance Specifications issued by the National Highway Safety Administration also end up not being as impressive as they appear to be at first blush. One obvious deficiency is that the speed accuracy test called for by the Specifications does not approach the conditions which exist on real highways. The testing of the speed of actual vehicles contemplated by the Specifications is really testing under closed circuit test track conditions. A tripod is used to hold the device steady and retroreflective areas may be temporarily affixed to the vehicle to increase the amplitude of the laser pulse echoes. The testing procedures involved might be a useful first step in a more comprehensive testing program, but the reality is that vehicles do not travel along our highways one at a time, tripods are not used and retroreflective areas are not attached to vehicles being driven along the highways. The reality is that the shape of motor vehicles is highly irregular and their surfaces reflect pulses off at many angles, with the result that most of the incoming pulse is not
Some of the objections posed by the defense experts, particularly by Mr. Roberts, seem to me to have been somewhat overstated. The defense experts appropriately pointed to many possible errors in the application of laser to the measurement of motor vehicle speed, but they suggested at times that it was almost conceptually impossible for those errors to be overcome. I think it is fairly clear that at least the most egregious errors have probably been eliminated from the laser speed detector. In this regard, it is important to take note of the experience which members of the New Jersey State Police have had with the use of the laser speed detector on our highways.
Sergeant Ricker testified about the classroom training and field training which State Police officers receive before they are certified as being qualified to use the laser speed detector. He also testified about the field practice which they must have with the detector before they are able to issue summonses. He detailed the operational checks which are made on each individual laser speed detector every day by an officer before the unit is used. He also spoke of the experience which he and other members of the State Police have had in the months during which they have been using the detector. I note that Sergeant Ricker’s testimony about the training of members of the State Police who use the detector
By this time, officers of the State Police operating under normal traffic enforcement conditions have obtained speed readings with the laser speed detector on thousands of motor vehicles. They do not keep comprehensive data with respect to the conditions under which they are obtaining the readings, and they are not simultaneously taking readings on targeted vehicles with other kinds of devices which have previously been found to be reliable. Accordingly, the experience of the State Police does not establish the degree of accuracy of the laser speed detector. However, it seems clear to me that the State Police are getting readings from the detector which are at least broadly sensible. State Police officers who take readings on a target vehicle on an interstate highway where their experience leads them to believe that the flow of traffic is probably moving in the 65 to 75 mile an hour range and where their visual observation leads them to believe that a particular vehicle is probably going around 70 miles an hour are not getting bizarre readings. They are not firing the laser speed detector device at a vehicle which they think is going around 70 miles an hour and getting readings in the range of 40 miles an hour or readings in the range of 95 miles an hour. They are getting readings which are fairly close to where the expect them to be. They are also not encountering many motorists who claim that the speeds being attributed to them are way out of line. This leads me to conclude that the error trapping mechanisms and programs contained in the laser speed detector are eliminating the most serious potential errors.
My own limited experience in observing Sergeant Ricker use the laser speed detector and my own limited experience in using it myself reinforced the view that the error trapping is in fact getting rid of at least the worst errors.
In urging me to find that the laser speed detector is a reliable device for measuring the speed of motor vehicles and in urging me to rule that the defendants may be convicted of motor vehicle violations based upon readings produced by the detector, the State points to the various approvals which have been granted to the detector by the agencies and organizations mentioned earlier in this opinion. The State has also pointed to the moderately widespread use of the detector in a number of state and local police departments in this country and in a number of law enforcement agencies in foreign countries. The State also urges me to take notice of the fact that the principle of using lasers to measure speed is broadly accepted as being scientifically sound.
The State has called my attention to eases such as State v. Wojtkowiak, 170 N.J.Super. 44, 405 A.2d 477 (Law Div. 1979), reversed, 174 N.J.Super. 460, 416 A.2d 975 (App.Div. 1980) (approving use of K-55 Doppler Radar device), and Romano v. Kimmelman, 96 N.J. 66, 474 A.2d 1 (1984). It is argued that there has been wide acceptance of the scientific techniques involved in the laser speed detector and there has been wide approval of the detector itself and that the Court should accept the detector as being a reliable device for measuring speed when used by a properly trained police officer. State v. Wojtkowiak and Romano v. Kimmelman can be read in a way which is broadly supportive of the State’s position in the present case, but my view of those cases and others cited in the State’s brief is that they do not require me to accept the laser speed detector as being reliable, given the proofs and analysis which have been presented in our present case.
I reach the conclusion just stated with considerable reluctance. If the laser speed detector were known to be accurate and reliable, it would, in my judgment, be markedly superior to radar in many situations that exist on the highways, roads and streets of New Jersey. New Jersey is a very densely populated state and its highways, roads and streets are crowded with traffic. Traffic flow along our interstate routes tends to be dense with traffic flow tending to be heavy in all lanes at almost all times. Wide beam radar under those circumstances requires the exercise of considerable skill and judgment by the operator in order to identify a speeding vehicle. The laser speed detector (assuming its accuracy and reliability) can much more readily target an individual vehicle in a heavy traffic flow than can radar. I am also aware of the fact that radar detectors are in very wide use among motorists, particularly among truckers, and they make it possible for chronic and persistent speeders to frustrate detection by radar. I see the laser speed detector as being potentially an extremely useful tool in enforcing speed laws in New Jersey.
My frustration is deepened by the fact that I suspect that the laser speed detector may be accurate and reliable. The problem is that I cannot be reasonably sure that it is accurate and reliable under the proofs and analysis which have been presented in this
The absence of detailed knowledge about the workings of the error trapping procedures in the laser speed detector is not necessarily an insurmountable obstacle to accepting the detector as being accurate and reliable. Even if we did know all the details of the error trapping procedures and could subject them to thorough intellectual analysis, and even if that analysis showed that they were conceptually sound, we would still need to have adequate performance testing of the laser speed detector under conditions which exist on our highways before we could accept it as reliable. Indeed, if we had adequate operational testing of the laser speed detector under actual highway conditions, we might be able to accept the detector as being reliable even though we did not have complete details about the way in which the error trapping procedures are designed and programmed. Good performance testing might conceivably put us in a position of being sure that the detector in fact worked reliably, although we were not sure precisely how it managed to achieve its results. This leads us to the lack of acceptable performance testing in this case.
In principle, it should be relatively easy to design performance tests which would let independent observers know how accurate the laser detector device truly is. The tests would have to include vehicles of varying sizes and shapes. They would have to be conducted under various conditions of traffic flow along actual highways and roads. They would have to be conducted at different times of the day under varying climatic conditions. They would have to involve target vehicles whose speed was reliably established either by controlling the driver of the vehicle or through simultaneous measurement of its speed by a reliable device other than the laser speed detector. The test data would have to be accurately recorded and reproduced for examination, analysis and replication by other persons and agencies. The factors that I have mentioned are illustrative, not exhaustive. Absent this kind of testing, I do not see how we can have any real confidence that the detector is sufficiently accurate.
I note that the Model Minimum Performance Specifications for Lidar Speed Measurement Devices issued by the National Highway Traffic Safety Administration in February 1995 state that the standard for speed measurement accuracy should be that the device would be within a tolerance of no more than one mile per hour in excess of the true speed and no more than two miles an hour below the true speed. The manufacturer in our case, Laser Technology, Inc., claims that the laser speed detector meets that standard. But there is no way in which we can be sure of that, in my judgment, under the present proofs. I do not think we can even be sure that the device is accurate over a wide range of conditions and with respect to a wide range of vehicles within a
The fundamental point is that there is no way of being sure under the present state of the proofs and analysis how accurate the detector is. I point out that a belief that the device is broadly accurate is not sufficient. If I were presented with a reading in a particular case indicating that a motorist was traveling 72 miles an hour in a 55 mile an hour zone, I would feel quite confident that the motorist was exceeding the 55 mile an hour speed limit. I would not feel confident that he was going 72 miles an hour. I would not feel confident that he was going 70 miles an hour. I could probably satisfy myself that he was going at least 65 miles án hour, but I might have some slight reservation about that. Under the laws of our state (and under the laws of many states) the degree to which somebody is exceeding the speed limit is important. The penalties both in terms of fines and points against one’s license increase with the increase of speed in excess of the limit. If police officers and municipal court judges do not have a good handle on the range of accuracy of the detector, it becomes difficult to enforce the speeding laws in a way which is predictable, uniform and fair. I do not think it would be necessary to have a range as tight as the plus one mile minus two mile range of the Model Minimum Performance Specifications. Perhaps a range as wide as plus or minus five miles per hour would be sufficient. We do need to know what the range is.
I recognize that courts should not routinely require thorough performance testing of every conceivable device that might be used in the course of law enforcement, or of every conceivable device whose efficacy comes into question in civil litigation. Frequently, common knowledge or the rather conclusory testimony of informed experts might be sufficient. But we are dealing here with a major innovation in law enforcement techniques. We are
I realize that courts should be hesitant about rulings which impose costs and burdens on litigants. However, it is important to note that highway safety and the fair and efficient enforcement of motor vehicle laws which are designed to promote highway safety are matters of very great concern and they are matters which involve enormous expenditures every year in this country. In 1994, 40,676 lives were lost on the highways, roads and streets of the United States. I do not know what the exact figures are, but I am sure that in any given year various governmental entities in the United States spend billions of dollars on the enforcement of motor vehicle laws, health insurance companies pay billions of dollars to pay for the injuries received by people in motor vehicle accidents and casualty insurance companies pay billions of dollars for such injuries and for property loss. Surely, a society such as ours can figure out some way to come up with the very modest amount of money which would be involved in subjecting an important device such as the laser speed detector to adequate performance testing.
ORDER
For the reasons expressed in the foregoing Opinion, speed readings produced by the LTI Marksman 20-20 Laser Speed Detection System shall not be used in the prosecution of any case arising under the motor vehicle laws now pending in the Municipal Court of the Township of Rockaway or in the Municipal Court of the Township of Parsippany-Troy Hills.
IT IS FURTHER ORDERED that, until further Order of the Superior Court, no municipal court in Morris County and no municipal court in Sussex County shall receive in evidence a speed reading generated by the LTI Marksman 20-20 Laser Speed Detection System in connection with any prosecution arising under the motor vehicle laws.
Reference
- Full Case Name
- IN THE MATTER OF THE ADMISSIBILITY OF MOTOR VEHICLE SPEED READINGS PRODUCED BY THE LTI MARKSMAN 20-20 LASER SPEED DETECTION SYSTEM
- Cited By
- 2 cases
- Status
- Published