California Speed Trap Defense 2026 — The Engineering Survey Rule (CVC 40802)

Speed Trap Defense California: CVC 40802 Explained (2026)

If the officer used radar or lidar on a road whose posted limit rests on an engineering and traffic survey, and that survey is not current, the measurement can be excluded. Which road you were on decides whether the rule reaches your case at all.

✅ Speed Trap Defense Can Work — Here's Why

California Vehicle Code 40802 defines a speed trap, and section 40803 keeps evidence obtained from one out of the case. Where a posted prima facie limit rests on an engineering and traffic survey and that survey is not current, the radar or lidar measurement can be excluded. The rule does not reach every road: local streets and roads, school, senior and business districts, and limits set by statute are treated differently. Excluding the measurement is not the same as a dismissal, and nothing in the section dismisses a case by itself.

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. Since AB 382 took effect on 1 January 2026 a survey is valid for 5 years, 7 years where the conditions in CVC 40802(c) are met, and up to 14 years where a registered engineer evaluates the segment and finds no significant change in roadway or traffic conditions

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 or lidar to measure my speed on [road name] in [city]. If the posted limit on that road rests on an engineering and traffic survey, then under CVC 40802 and 40803 the measurement is inadmissible unless the prosecuting agency establishes that a current survey supports the posted limit. I request that the court require the agency to produce the engineering and traffic survey for this road, together with the date it was completed. Without it, I ask the court to exclude the speed measurement and to weigh the remaining evidence accordingly."

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: cited under CVC 22348(b), a statutory maximum rather than a survey-based limit, so the survey argument has nothing to bite on
School zones and business districts: Statutory speed limits (25 mph school zones, 15 mph alleys) don't require engineering surveys

If your ticket involved a speed trap zone, you have one of the strongest grounds to contest it. Our complete 2026 guide to fighting a California speeding ticket → covers the Speed Trap Defense, Trial by Written Declaration process, and all 5 defense strategies, including how to file the discovery request for the engineering survey before your TBWD deadline.

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Common questions

Frequently asked questions

What is a speed trap in California?

CVC 40802 defines a speed trap. The part that matters most in practice is a stretch of road where a prima facie speed limit is enforced with radar or lidar without a current engineering and traffic survey supporting that limit. Where the definition applies, CVC 40803 keeps the speed measurement out of evidence. It does not reach every road: local streets and roads, school, senior and business districts, and limits set by statute are treated differently. Nothing about it dismisses a case automatically.

What is CVC 40802?

CVC 40802 is the statute that defines a speed trap, and CVC 40803 is the one that excludes evidence obtained from it. Since AB 382 took effect on 1 January 2026 an engineering and traffic survey is valid for 5 years, 7 years where the conditions in subsection (c) are met, and up to 14 years where a registered engineer evaluates the segment and finds no significant change in roadway or traffic conditions.

How do I know if my ticket was issued from a speed trap?

Key signs: (1) The officer used radar or lidar to measure your speed. (2) The road has a posted prima facie speed limit (usually 25-65 mph) rather than a statutory speed limit. (3) The road is a local street, not a freeway. You can request the engineering survey from the court or the issuing agency to verify if one exists.

How do I use the speed trap defense in a Trial by Written Declaration?

In your TR-205 declaration, say that the speed measurement should be excluded under CVC 40803 because the prosecution cannot show a current engineering and traffic survey for that limit, and ask the court to require it. A discovery or public records request before your filing deadline is how you find out whether a survey exists and when it was completed. This is an evidentiary argument, not an automatic dismissal, and it only applies where the posted limit rests on a survey.

Does the speed trap defense work on freeways?

Usually not. The argument turns on a posted limit that rests on an engineering and traffic survey. A statutory maximum, such as the 65 mph limit in CVC 22349(a), does not rest on a survey, so the survey argument has nothing to bite on. Check which kind of limit was posted where you were cited before you build a defense around it.