Speed Trap Defense California: CVC 40802 Explained (2026)
If the officer used radar or lidar and the road doesn't have a valid engineering survey — your ticket may be dismissed as an illegal speed trap under California law.
✅ Speed Trap Defense Can Work — Here's Why
California Vehicle Code 40802 prohibits speed enforcement using radar or lidar on roads without a current engineering and traffic survey (E&TS). Many local roads lack current surveys. If the survey is missing or outdated, the radar evidence is legally inadmissible — and your ticket must be dismissed.
What Is a Speed Trap? (CVC 40802)
Under California Vehicle Code Section 40802, a "speed trap" is defined as:
A particular section of a highway measured as to distance and used or operated for the purpose of trapping motorists or pedestrians violating the speed laws... [or] a road or portion of a road with a prima facie speed limit imposed by this code... if that speed limit is not justified by an engineering and traffic survey.
In plain terms: if a cop used radar or lidar to clock your speed on a road that doesn't have a valid engineering survey, your ticket may be illegal.
When Does the Speed Trap Defense Apply?
The speed trap defense applies when ALL of the following are true:
- The officer measured your speed using radar or lidar (not pacing or visual observation)
- The road has a prima facie speed limit — a posted limit that isn't the statutory default (not a freeway, school zone, or business district)
- The road is a local or arterial street (cities and counties are required to maintain surveys; state highways operated by Caltrans generally don't need surveys)
- The engineering and traffic survey is missing, expired, or not current — surveys must be updated every 5-7 years (10 years with a speed feedback sign)
How to Request the Engineering Survey
Before your Trial by Written Declaration, submit a discovery request to the court asking for:
- The engineering and traffic survey for the road where you were cited
- Proof that the survey was current and valid on the date of your citation
- The radar/lidar calibration records and officer's certification
If the city or county cannot produce a valid, current engineering survey, the radar evidence is inadmissible under CVC 40803, and the officer's speed testimony becomes legally insufficient to convict.
How to Use This Defense in Your TR-205
In your Trial by Written Declaration (Form TR-205), include the following argument:
Sample defense language:
"The citing officer used radar/lidar to measure my speed on [road name] in [city], which is a prima facie speed zone under CVC 22352. Pursuant to CVC 40802 and 40803, radar evidence is inadmissible unless the prosecuting agency can establish that a current engineering and traffic survey exists justifying the posted speed limit. I hereby request that the court require the prosecuting agency to produce the engineering and traffic survey for this road. If no current survey can be produced, the radar evidence must be suppressed and the case dismissed."
Limitations of the Speed Trap Defense
- Freeway citations: This defense does not apply to citations issued on state highways (65 mph statutory limit) or CHP-patrolled freeways
- Visual observation only: If the officer paced you by vehicle (not radar/lidar), the speed trap law doesn't apply
- Over 100 mph: Speed trap defense still applies technically, but judges take these more seriously
- School zones and business districts: Statutory speed limits (25 mph school zones, 15 mph alleys) don't require engineering surveys
Frequently Asked Questions
What is a speed trap in California?
Under CVC 40802, a speed trap is a road where prima facie speed limits are enforced using radar or lidar without a valid engineering and traffic survey. Evidence from an illegal speed trap is inadmissible under CVC 40803.
What is CVC 40802?
CVC 40802 defines speed traps and prohibits enforcement on roads where prima facie speed limits aren't supported by a current engineering survey. Violations of this law make radar/lidar evidence inadmissible.
How effective is the speed trap defense in California?
Results vary significantly by city and court. Some cities maintain outdated surveys, especially smaller municipalities. The defense works best on local streets in smaller cities or counties where engineering survey maintenance may lag. It rarely works on major state highways or freeway citations.
Does the speed trap defense work for CVC 22350 tickets?
CVC 22350 (unsafe speed) is a prima facie speed law — if the officer used radar and the road lacks a valid engineering survey, the speed trap defense applies. However, 22350 also allows officers to testify about visual observation, so the defense may not fully dismiss the ticket.
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