Additional Resources for DWI and Other Serious Cases
1. How do the police measure a driver’s speed?
Generally, police use the following methods to catch you speeding:
a. A visual estimate. The officer sees your car and estimates how fast you are going.
b. Pacing. The police officer follows your vehicle at the same speed you are traveling and checks the police car’s speedometer to see how fast you are going.
c. Radar. The officer points a radar gun at your car and it calculates your speed.
d. Laser. The officer points a laser gun at your car and it calculates your speed.
2. Why is the concept of hearsay important in challenging a speeding ticket?
Be aware of any hearsay in a speeding case in Municipal Court. In challenging your ticket, you will want to be aware of a key legal rule called “hearsay” that could help your case. The hearsay rule bars any testimony that quotes information from somebody other than the witness. This is sometimes called the “he said” rule because it forbids a witness from testifying to what somebody else said he saw. There is a huge catch to this hearsay rule. You must affirmatively object or the judge will allow the testimony.
Here are the most common scenarios in which a prosecutor is most likely to use hearsay evidence to prove a speed violation:
a. An officer testifies about what another driver told her about your behavior.
b. The officer who wrote your ticket testifies about what another officer told him.
c. Where two officers were in a patrol car, and one of them observed your driving. The officer who did not see your driving may not testify to what the other officer told him about your driving.
d. The prosecutor tries to introduce an absent officer’s police report or other written record into court in place of live testimony. If this should occur, then you should simply object on the basis that it is hearsay. If the officer is not present, then the written report is inadmissible hearsay testimony.
3. What is pacing?
Many speeding tickets are issued from the police officer following or “pacing” a suspected speeder and using his or her own speedometer to clock the suspect’s speed. With this technique, the officer must maintain a constant distance between her vehicle and the suspect’s car long enough to make a reasonably accurate estimate of its speed.
The road configuration where you were busted may help prove inadequate pacing. Hills, curves, traffic lights, and stop signs can all help you prove that an officer did not pace you long enough. For example, an officer following your vehicle a few hundred feet behind will often lose sight of it at a curve, not allowing enough distance to properly pace the vehicle. Similarly, if you were ticketed within 500 feet of starting up from a stop sign or light, the officer will not be able to prove that she paced your car for a reasonable distance.
4. How can pacing be inaccurate?
There are many ways that pacing results can be proven to be inaccurate. The farther back the officer, the less accurate the pace for an accurate “pace.” The officer must keep an equal distance between her car and your car for the entire time you are being paced. The officer’s speedometer reading, after all, means nothing if she is driving faster than you are in an attempt to catch up with you. That’s why an officer is trained to “bumper pace” your car by keeping a constant distance between her front bumper and your rear bumper. Pacing correctly requires both training and good depth perception. Moreover, pacing becomes more difficult the farther behind the officer is from your car. The most accurate pace occurs where the officer is right behind you. However, patrol officers like to remain some distance behind a suspect, to avoid alerting a driver who periodically glances at his rear view and side view mirrors.
Therefore, if you know an officer was close behind you for only a short distance, your best tactic in court is to try to show that the officer’s supposed “pacing” speed was really just a “catch up” speed. You will want to ask the officer the distance over which he tailed you. If he admits it was only a short distance, then it will help your case. Your goal is to use the speeds that the officer testified to for his car while he was pacing you to argue that he used his speed while closing in on you as you were driving under the speed limit.
5. Is pacing accurate if it is done during dusk or at night?
Pacing is much more difficult in the failing light of dusk or in complete darkness, unless the officer is right on your tail. In darkness, the officer’s visual cues are reduced to a pair of taillights. Also, if an officer paces a speeder’s tail lights from far back in traffic, she’ll have trouble keeping the same pair of taillights in view.
6. How do the road conditions affect pacing?
Pacing is easiest and most accurate on a straight road, with no hills, dips, or other obstacles and where the officer can see your vehicle continuously as she follows you. This allows her to keep her car at a constant distance behind you while she paces your speed. Hill, freeway interchanges, dips, curves, busy intersections, and heavy traffic make for a poor pacing environment. All of these obstacles can be used to challenge the accurate pacing of your vehicle.
7. How does radar work?
Radar guns aim an electromagnetic signal at a target vehicle and pick up the return signal reflected off the vehicle. The Doppler effect causes the frequency of the return signal to shift by an amount dependent on the relative speeds of the source of the original signal and the target. Speed radar devices measure the frequency of the reflected signal and compare it with the frequency of the original signal to determine the speed of the target vehicle. A radar beam varies in width comparative to it’s length‑the further the radar’s “zone” extends from the unit the wider it will be. Thus, there must be some evidence in a radar case that the radar was not inadvertently picking up any other moving objects that may also have been within the radar’s “zone.”
8. How is radar used? What are the types of radar equipment?
Although many brands of radar units are in use, they all fall into two types, car mounted units that can be operated while the officer’s vehicle is stationary or moving, and hand‑held radar “guns” often used by motorcycle officers in a stationary position.
9. What are car-mounted radar units?
Most radar antennas used in patrol vehicles are shaped something like a side‑mounted spotlight without the glass on the front.
They are usually mounted on the rear left window of the police car facing toward the rear. The officer reads your speed on a small console mounted on or under the dash. The unit has a digital readout that displays the highest speed read during the second or two your vehicle passes through the beam. This means that once you go through the radar beam, slowing down does no good.
These units also have a “speed set” switch that can be set to the speed at which the officer has decided a ticket is appropriate. This allows the officer to direct his attention elsewhere while your car travels through the beam. If the speed reading exceeds the “speed set” value, a sound alarm goes off. The officer looks at the readout, then at your car, and takes off after you.
Most modem police radar units can also operate in a “moving mode,” allowing the officer to determine a vehicle’s speed even though her own patrol vehicle is moving. In moving mode, the radar receiver measures the frequency of two reflected signal the one reflected from the target vehicle‑as in the stationary mode‑and another signal bounced or reflected off the road as the patrol vehicle moves forward. The frequencies of these two signals indicate the relative speed between the officer’s vehicle and the target, and the officer’s speed relative to the road. The target vehicle’s speed is then calculated by adding or subtracting these two speeds, depending on whether the two vehicles are moving in the same, or opposite, directions. This calculation is done automatically, by the electronics in the radar unit.
10. What are hand-‘held radar units?
Hand-held radar guns are used most often by motorcycle officers. A radar gun is simply a gun shaped plastic mold containing the transmitter, receiver, and antenna. The antenna is normally mounted at the front of the gun, and a digital speed readout is mounted on the back. A trigger is included, allowing the officer to activate the radar beam only when she sees a car that appears to be traveling fast enough to spark her interest.
11. How can radar readings fail?
Contrary to many boastful municipal prosecutors, new technology has not completely ironed out problems known to cause radar malfunctions. Most screw ups result from the radar’s operation in real-world conditions, which are often far less than ideal. Moreover, human error can also cause radar devices to fail.
The best way to point out all the pitfalls of radar readings is to subpoena the radar unit’s instruction manual. The manufacturer will usually include a page or two on inaccurate readings and how to avoid them. If you study the manual, you may find a way to attack its reliability in court using the manufacturer’s own words. It is important to make sure that the manual is complete. Police departments have been known to tear out pages that discuss common radar screw ups from the radar manual before responding to a subpoena. So be sure to look to see if any pages are missing and, of course, point out any gaps you discover.
12. What are the common malfunctions and sources of inaccurate readings?
a. More Than One Target
Radar beams are similar to flashlight beams. The farther the beam travels, the more it spreads out. This simple fact often results in bogus speed readings, since it’s common for a spread‑out beam to hit two vehicles in adjacent lanes
It is very possible that the officer obtained a radar reading from another vehicle. At trial, ask the officer if his radar unit was on automatic. The chances of registering the speed of the wrong car go way up when an officer, points his radar unit at a highway and puts it on the automatic setting. This is true because the officer isn’t pointing his radar unit at a specific vehicle. Therefore, the beam angle width means the unit could be picking up one of several cars going the same, or even opposite, directions. In this case, ask the officer whether there was other traffic in either direction. If his answer is “yes,” ask him which direction. If there was traffic in the direction opposite you, follow up and ask him whether the unit responds to traffic in both directions. Either way, if there was other traffic, be sure to raise the possibility in your closing argument that the radar unit clocked the wrong vehicle.
b. Wind, Rain, and Storms
Although metal reflects radar beams better than most surfaces, pretty much any material will reflect radar waves to some extent. In fact, on windy days, windblown dust or even tree leaves are often read by radar devices. And sometimes these spurious readings can be attributed to your vehicle.
Windblown rain can also reflect enough energy to give false signals, particularly if the wind is strong enough to blow the rain close to horizontal. The more rain or wind, the more likely an erroneous radar reading will result. Pre-thunderstorm atmospheric electrical charges can also interfere with a radar unit. That’s because electrically charged storm clouds can reflect a bogus signal back to the radar unit even though they are high in the sky. If such a storm cloud is being blown by the wind at sufficient speed, a false radar reading may result.
c. Calibration Problems
Every scientific instrument used for measuring needs to be regularly calibrated to check its accuracy. Radar equipment is no exception. It must be checked for accuracy against an object traveling at a known (not radar determined) speed. If the speed on the radar equipment matches the known speed, the unit is properly calibrated. In practice, the best way to do this is to use a tuning fork as the moving object. While this may seem a far cry from a moving car, the use of a tuning fork is scientifically sound; tuning forks, when struck against a hard object, vibrate at a certain frequency which we hear as an audible tone.
It is time-consuming to use a tuning fork as a calibration device. So a second, but far less accurate, method has been developed to check the accuracy of radar units. This consists of flicking on the “calibrate” or “test” switch built into the radar unit itself and seeing if it calibrates properly. The unit reads a signal generated by an internal frequency generating device, called a “crystal.” The resulting number is supposed to correlate with a certain predetermined speed.
Unfortunately, there is a big problem with this sort of calibration testing. There are two types of circuits in the unit, frequency circuits and counting circuits. Flicking the calibration switch tests only the counting circuits. In short, if the frequency circuit is not calibrated, the radar unit may well be inaccurate.
The fact that an internal “calibrate” test isn’t a substitute for a tuning fork explains why it’s so important in any traffic trial involving the use of radar to cross‑examine the officer and see whether she really did use a tuning fork before you were ticketed. Typically, they are required to use the tuning fork at the beginning and end of their shifts.
d. Pulling You Over As Part of a Group of Cars
In situations where several cars proceed over the speed limit, some especially any zealous officers will take a radar reading on the “lead” vehicle and then pull it over, along with one or two followers. In court, the officer will try to use the reading for the first vehicle as the speed for everyone else.
13. Is the laser accurate in measuring a driver’s speed?
Laser devices, also known as LIDAR (light distance and ranging), use a time/distance calculation to measure speed. The devices aim a narrow band of light at the target vehicle and measure the time it takes to receive the reflected light. Because the speed of both the original light pulse and its reflection are traveling at the same speed (the speed of light), differences in the time it takes the transmitted light to strike the target vehicle and return can be used to calculate the speed of the vehicle. Unlike radar, lasers can pinpoint specific vehicles in heavy traffic.
Laser detectors are the most recent addition to the traffic officer’s arsenal of speed measuring devices. Built to look and act like a hand-‘held radar gun, a laser detector uses a lasered powered beam of laser light that bounces off the targeted vehicle and returns to a receiver in the unit. The unit then electronically calculates the speed of the targeted vehicle. Laser detectors are supposedly more accurate than radar units.
One advantage for police officers of the laser gun is that the light beam is narrower than a radar beam, meaning that it can be more precisely aimed. This is true even though laser detectors use three separate beams, because the combined width of the three beams are still much narrower than a single radar beam at the same distance. This technology reduces, but does not eliminate, the chance that the speed of a nearby car will be measured, instead of the speed of the car at which the operator aims the gun.
14. Does the officer have to be certified to operate radar?
Most law enforcement agencies have some kind of certification process that must be completed before an officer is allowed to use radar. This may be mandated by law or departmental policy. Federal guidelines spell out certain recommended minimum standards for radar operators but these are only recommendations, not requirements. A motorist may ask if an officer possesses a certificate but it is probably rare that an agency will require the officer to present it in the field.
15. How much does the officer have to know about how the radar works?
The officer needs to know how to setup, test, operate, and interpret the readings obtained from radar. He also needs to understand the basic principles of how the radar works. He does not need to know how to build or repair the unit nor does he have to understand all the electronic circuitry any more than the average homeowner needs to know how to build or repair a television set in order to use it.
16. Does a vehicle’s shape and size affect its ability to be clocked with radar?
Yes. It stands to reason that a smaller target will need to be closer to the radar in order to be clocked. An aerodynamically shaped vehicle will present a slightly smaller target for the radar and will likewise need to be closer to the radar before being clocked.
17. Can an officer issue a speeding ticket without radar?
Yes. New Jersey case law has consistently held that a trained officer can visually estimate the speed of a vehicle with some degree of reliability. Speed estimations are usually a part of radar operator training and some officers become quite skilled at this. There may be situations when an officer sees what he knows to be a speeder traveling well over the posted limit but the radar is not positioned to obtain a reading, or maybe he has no radar at all. This does not prevent him from stopping the motorist and issuing a speeding ticket.
18. Can other radio transmitters interfere with the radar?
Yes, in certain instances they can, but this is relatively rare. This can vary from one radar to another and is dependent upon the frequency of the radar and the strength of the signal source. Most modern radars have a built in “RF” (radio frequency) indicator which will automatically blank the radar’s readout screen during activation by a strong RF signal that exceeds a predetermined threshold level. Due to their higher power outputs, TV and commercial radio stations can cause interference at close range. Cell towers, ham radio repeaters, personal cell phones, wireless Internet and other devices are relatively low powered and aren’t likely to cause interference, even at very close range. If by chance they should, the radar will temporarily go blank and readings will not be possible. Radar manufacturers know their products are going to be used in a radio rich environment in a police vehicle so it stands to reason their radars will be specifically designed to work in that type of environment. A rule of thumb is, if your cell phone will function without interference, so will the radar.
19. Are there other sources that can interfere with radar?
Yes. Nearby electrical lines, fluorescent lighting, even the patrol car’s own heater blower motor can cause interference. These problems are addressed in training and a good radar operator will immediately know when these problems are present. On some older radars these sources can cause fake readings on the radar while the newer radars are designed to eliminate most of these. Nonetheless, the trained radar operator is taught to watch for these problems and isn’t likely to misinterpret them.
20. How many targets can the radar clock at once?
Some radars can clock several targets simultaneously while others are limited to one at a time. Either way it is up to the operator to properly identify which target is being clocked before initiating a traffic stop.
21. Does the radar tell the officer which vehicle it is clocking?
No. Target identification is the ultimate responsibility of the radar operator. Keep in mind this does not apply to LIDAR where the laser is aimed at a specific vehicle. LIDAR target identification is very accurate
22. How does the officer know which vehicle he is clocking?
The officer is responsible for visually verifying the target vehicle. Cases of mistaken identity are possible if the officer is poorly trained or inexperienced. The more vehicles within the range of the radar, the more difficult target identification becomes. Some new radars have a feature that tells the officer if the target is closing or going away.
23. What is the range of police radar?
This will vary depending on the model of radar, the volume of traffic present, the terrain, and the size of the targets being clocked. Some radars are capable of clocking vehicles over a mile away. The author has used older model radars that under the right conditions could track vehicles at almost two miles.
24. How does the officer go about checking the radar’s accuracy?
The procedures may vary between models. Tuning forks are used to check the radar readings and most radars also have some form of an internal calibration test. These tests are customarily performed at the beginning of a shift and sometimes more often. The tuning forks simulate the Doppler shift of a vehicle at a known speed. Most radars also have means of insuring that the digital display has no burned out elements which could cause a misreading of the numbers. In addition to these tests an officer can check the radar by driving and verifying the indicated speed against a certified speedometer or using it side by side with another radar to ensure they both read the same speed on the same target. Many newer radars also do periodic automatic self tests.
25. Does the radar have to be re-calibrated periodically?
Not unless it is required by department policy or by law. Radars contain solid state electronics and have no higher failure rate than other similarly engineered electronic devices. Most radars will simply cease to function when something goes wrong. In those few instances where a radar continues to work when a malfunction exists the officer operator should recognize that a problem exists and take the unit out of service for repair or replacement.
26. Does the weather affect the radar?
Yes, but usually not to the extent some people might think. By the very nature of the radar’s location inside a police unit they are built to withstand a great deal of shock and temperature and humidity variations. Precipitation may reduce the effective range of the radar by causing the signal to scatter and break up more quickly than in clear air but the accuracy of any reading obtained will be unaffected. Extremes of heat or cold might have a slight temporary effect on the accuracy of the tuning forks used to test the radar while the radar itself remains accurate.
27. When I was pulled over, the officer didn’t let me see the radar reading. Is this a valid ground for a dismissal?
No. The officer is not required by law to show the radar readings to a ticketed driver. This issue has been tried in the courts and the courts have decided that it is not relevant and the officer does not have to show you. Most officers being reasonable will show you the reading if it is possible for them to do so.
At times the officer will not want to, or be unable to because of any number of reasons. The officer may feel it is not safe for you to get out of your car stand on the highway as a pedestrian to look at the reading, especially if this was on a major highway.
28. I might have admitted my speed to the officer, will he use it against me in court?
For a speeding trial the officer is not going to use any statements against you in court. They will not use this against you or tell the Municipal Court judge what you may have said. It’s not relevant to the case and the judge will not want to hear this evidence.
29. Can I dispute the speeding ticket by saying that my speedometer was off?
It is not a defense to the charge of speeding to say that your speedometer was not working. A speedometer is not a required piece of equipment in a motor vehicle. You are always responsible for the speed of your vehicle. It is not a defense to say you didn’t know or you did it by mistake.
30. Do radar or laser make mistakes? Is there a defense to the speeding charge?
Any instrument can make mistakes. Radar and laser are accurate to plus or minus one percent, so if you were stopped at 100km/h the speed may have been 101/km/h or 99km/h. The operator can make mistakes too but you have to know the questions to ask in a trial. In a speeding trial an officer has to cover approximately thirty points to prove the case. If the officer can do this properly no one can win the case, and the Municipal Court judge has to enter a conviction. Speeding ticket trials are won on technicalities presented properly before the court.
Speeding trials are won from knowing all the issues about the operation of radar, qualifications together and disputing the essential elements of a speeding charge. The officer must provide the evidence to the court without a reasonable doubt.
If you don’t know how the radar works, the qualifications required by the officers, testing procedures required, rules of evidence, what a leading question is and what is hearsay evidence you are not qualified to run a trial and defend yourself.
Speeding trials are based on technical aspects of procedure and law. If you don’t know all of the issues, you will be convicted. You need to have experience and knowledge to conduct a speeding trial. If you don’t know what a filing date is, the proper set fine, or the service boxes, then you’re not qualified to defend yourself. Remember the officer probably has given evidence before the court hundreds of times, how many speeding trials has the person who received the ticket run.
