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Traffic Court

Contents -- Radar / Speed Requirements | Take it to Court? | The Cosine Effect Defense
CAVEAT: This document is not intended to give legal advice in any way. This section and any other sections or references to the law or courtroom activities is based solely on the author's personal experiences and observations.

All technical information and conclusions in the Police Radar Handbook is quantifiably described using illustrations, graphs, tables, or mathematical formulas -- based on or derived from fundamental scientific and engineering principles, published factory specifications, measured data, or U.S. Government documents.

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Radar and Speed Limit Requirements

Radar FCC License
Microwave police radars are regulated by the Federal Communications Commission (FCC) Rules and Regulations, Part 15, 20, and 90, radiolocation services. The FCC specifics technical standards such as operating frequency, bandwidth, power density, etc. The rules do not cover the calibration of radar units, radar accuracy, or operator capability requirements.

Police do not need an FCC license to operate traffic radar if their radios are licensed, however other state, local, or agency requirements may apply.

Laser Radar
Some states limit or restrict laser radar use. In New Jersey troopers can only use laser radar in clear weather and for vehicles less than 1000 feet.

NHTSA / IACP Consumer Product List (CPL)
The National Highway Traffic Safety Administration (NHTSA), in conjunction with the International Association of Chiefs of Police (IACP) and the Law Enforcement Standards Laboratory of the National Institute of Standards and Technology (NIST) developed testing protocols and performance standards for speed measuring devices. Radars, microwave and laser, that meet the standards are included in the NHTSA / IACP Conforming Product List (CPL) of approved speed measuring devices. See IACP Radar/lidar Testing for CPL listed radars.

Time / distance measurement features not approved or tested. Moving radars approved only for automobile or truck use, not motorcycles, boats, etc. CPL approval insures that a microwave or laser radar model, at least the unit tested, meets basic minimum standards set by the NHTSA, IACP, and NIST. Some states and agencies require speed measuring devices be CPL approved.

The Manual on Uniform Traffic Control Devices (MUTCD)
The Manual on Uniform Traffic Control Devices (MUTCD), established by federal law in 1966, sets national standards for highway and road issues. The MUTCD requires speed limits are to be determined by an Engineering Study as defined by MUTCD 1A.13. An Engineering Study must also be done before any speed limit can be changed. If some government body changes a speed limit without a proper study, the speed limit is illegal.

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Take it to Court

Case Law

Police know the uniform, flashing lights, siren, car markings, loaded guns, and the power to arrest are intimidating factors when issuing a speeding ticket. Some officers are intentionally intimidating to help insure tickets are not challenged. Don't let intimidation be a factor in determining whether to challenge a ticket. Do keep in mind the odds of successfully beating a radar ticket, innocent or not, are against the defendant, but not zero.

Several factors must be considered before deciding to fight a speeding charge. First and most important one must be wrongly accursed, do not try to beat a charge if you're guilty. However, if you were not speeding as fast as accused, you might plead for the lesser speed violation to lower the fine if you can convince the judge. With some insurance companies the higher the speed the more the insurance rate increases on conviction. The court clerk should know if the fine would change for a lower speeding ticket, and your insurance agent should know if rates change with speed.

In general the more people the court serves the better chance for a fair hearing. A small city or county court is usually the hardest to prove a case and in some situations it is virtually impossible to walk away without paying something.

Some courts require the defendant to plead guilty or not guilty in a pre-trial hearing, at which time a trial date is set for a not guilty plea. This means two court appearances. Some courts let defendants mail in the plea so only one court appearance is necessary.

Preparation for Court
Be prepared to document as many facts as possible. Ground and aerial photographs of the site could be helpful. Show approximate distances from the map scale or actual measurements. Note approximate locations for vehicle and radar at start and finish of the radar track. Be careful any maps or photographs are not outdated.

Some experts suggest filing a Discovery motion or a request for Discovery form with the court clerk for some or all of the following items;

Discovery Motion Items
Video - Dash Camera or other Video / Audio
Radar Documents - Make, Model
- Manufacturer Certificate of Calibration
- Operator Manual and Specifications
- Calibration Test Log Sheets
Tuning Fork Documents
not laser radars
- Resonance and Radar Frequency
- Tuning Fork Calibration Logs
Officer Notes - Notes of incident and log book
Officer Training - Certificate of Competency
- Training Materials
- Training Classes
Department Policies - Radar Standards and Practices
- Test Procedures

You or your lawyer must go through the court clerk to request discovery information by filling out a form, or making a formal request in writing regarding specific information. In most cases an additional processing and copy fee is required. If the officer cannot produce a reasonable request for information the charge may be dismissed.

Some schools of thought suggest that requesting information might negate any chance of the officer not showing up for court in which case the charge should be dismissed.

Officer Presentation
Most officers are trained to collect certain information in the event the case is disputed. Below list typical minimum information an officer should be prepared to present in court.

Officer Presentation
1. Establish time, place, location of radar.
2. Establish of offending vehicle.
3. Identify the offending vehicle.
4. Establish and idientify vehicle operator.
5. Visually observed apparent excessive speed.
6. Observed vehicle was alone out front,
or fastest for Fastest Mode.
7. Established radar tested before use,
- Self Test run before and after use.
- Tested against vehicle with calibrated speedometer.
Microwave Radar
- Tested with Tuning Forks.
Laser Radar
- Beam alignment tested.
- Range Accuracy Tested
8. State qualifications and training.

Defendant Presentation
When disputing a speeding charge one should already know the answers to most of the questions listed below. If for any reason some or all of the pertinent information is not known in advance, ask the officer in court under oath. Do not ask questions the officer has already addressed unless disputed. The judge will side with the officer on most disagreements such as exact locations, vehicle placements and distances unless one has hard proof.

Radar / Lidar Documentation
  • Is the radar factory certified?
  • Is the radar CPL approved?
  • Make, Model, Year purchased?
  • Hand held or fixed mounted?
Laboratory Calibration
  • Radar / Lidar in Calibration?
    - Last and next calibration test?
    - Who conducts calibration test?
  • Microwave Radar?
    - Tuning forks last and next calibration?
    - Who conducts tuning fork calibration?

Operator Testing
  • What are operator Testing Guidelines?
    - When and how often self-test run?
    - Site pre-tested with test vehicle?
  • Operation Guidelines?
    - Minimum time for stead stable track?
    - Radar distance from traffic lanes?
  • Who established guidelines?
  • Microwave Radar
    - Radar tested with tuning forks?
    - Demonstrate test procedure?
  • Laser Radar?
    - Range accuracy tested, what range?
    - Horizontal and Vertical Alignment Tested
    What range?

Radar Information
  • Radar Band? X, K, Ka, IR
  • Beamwidth?
  • Speed measuring range min to max?
  • Maximum detection range?
  • Sample time for 1 speed reading?
  • Stationary and Moving modes?
  • Fastest mode?
  • Opposite and same-lane traffic modes?
  • Range Control?
  • Patrol Speed Blanking (moving mode)
    --Purpose and use?

Officer Training and Events
Officer Training
  • Hours of training?
  • Who trained?
  • Time in radar enforcement?
  • Speeding citations issued that day?
  • Number of citations disputed?
  • Quota system in agency?
  • Radar distance from traffic lane?
  • Lanes covered by radar beam?
  • Range vehicle first detected?
  • Time vehicle tracked?
  • Steady stable signal?
  • Any Cosine Effects observed?
  • Range Control adjusted for conditions?
  • Patrol vehicle or other transmitter on?
  • Total transmitters on patrol vehicle?

Not all questions or details are appropriate for all cases. The better you are prepared, the better the odds of a favorable outcome. The more pertinent questions you can ask that the officer cannot answer, the stronger your case.

Court Day
On court day be prepared to spend the entire day. Do not be surprised that typically 100 or more people are scheduled at the same time. Before a trial one of the prosecutors may try to talk you into pleading guilty. Be prepared for scare tactics, intimidation and time-consuming distractions designed to make one believe pleading guilty is better than going to trial. No plea bargain, no deal.

If the prosecutors believes your case is strong you may be offered a plea bargain. The stronger you make your case the better the plea bargain, but do not tip too much information in the event you go to trial. Sometimes you can bargain the plea bargain, sometimes it's take it or leave it. Bargaining to pay the fine and to not have the ticket on record for the insurance company to see is sometimes the best deal, sometimes not. Most plea bargains also have a probation period of 30 to 90 days, if you don't get any tickets during probation the ticket goes off the record.

If you do go to trial forget the prosecutor, now the judge is the only one to persuade. Don't try to make a case with material you don't thoroughly understand, most judges recognize a shaky case. Do not be afraid to ask the officer specific, pertinent and detailed questions about the radar. The more questions the officer cannot answer, the less creditable the prosecution's case. An officer that does not have creditable working knowledge about radar should not be operating one.

The general format for traffic court is the prosecution will state their case and question the officer for support. You will then have a chance to state your case and question the officer. The prosecutor will then try to shatter your case by questioning you. Be aware judges have authority to conduct court procedures to their satisfaction, this means court procedures vary with state, county, city, judge, magistrate and arbitrator.

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The Cosine Effect Defense

Minimum Range
The Cosine Effect works in favor of the motorists in terms of measured speed, a little lower than actual speed. The Cosine Effect also puts some limitations on the radar, mainly a minimum range. Vehicles less than minimum range cannot be measured. The greater the distance the radar from the traffic lane, the greater the minimum range. A vehicle inside minimum range could be mistaken for a vehicle just outside minimum range.

Large Cosine Effect Angle
A common occurrence is the radar cosine effect angle is so severe when measured speed is corrected for the angle the corrected speed is excessively high and unlikely. This would indicate the radar was tracking another signal such as another vehicle or interference from a transmitter in or near the patrol vehicle.

For example if the cosine angle is 60° radar measured speed is half true speed. If the officer states observed estimated vehicle speed to be about the same as the radar measured speed, one could argue the officer's judgment was biased incorrectly by the radar. If the officer's estimated speed conflicts with radar corrected speed, which one is correct, if any?

Observed Cosine Effect
The cosine effect causes measured speed to change, the closer the target vehicle the lower the measured speed. A good steady stable track will show cosine effects as the vehicle gets close to the radar, measured speed decreases and stops at minimum range.

A 75 mph vehicle approaching a microwave or laser radar will display speed readings that look something like "75 - - - - - - - 74 - - - - - -73 - - 72 - 71". The sequence is reversed for receding vehicles, speed increases. Noticeable speed changes should only take place relatively close to the radar. The speed readings are predictable and should be noticeable to the officer.

Police Radar Information Center

Traffic Court
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