Please ensure Javascript is enabled for purposes of website accessibility

Criminal Practice – Search & Seizure – Probable Cause — Traffic Stop – Visual Speed Estimate — Insufficient

Criminal Practice – Search & Seizure – Probable Cause — Traffic Stop – Visual Speed Estimate — Insufficient

Listen to this article

U.S. v. Sowards (Lawyers Weekly No. 12-01-0692, 53 pp.) (Wynn, J.) No. 10-4133, June 26, 2012; USDC at Statesville, N.C. (Voorhees, J.) 4th Cir. Full-text opinion.

Holding: A deputy’s visual estimate of a driver’s speed – uncorroborated by radar or pacing and unsupported by any other indicia of reliability – did not provide probable cause to stop the driver for driving 75 in a 70-mph zone, and the 4th Circuit says the district court erred in denying defendant’s motion to suppress cocaine discovered in the car after the traffic stop.

We hold that several of the district court’s material factual findings were clearly erroneous. First, it was clear error to find the deputy was “trained to estimate speeds.” The record indicates he was trained to use a radar unit; his testimony confirmed he used absolutely no technique or method to visually guess vehicle speeds. Second, it was clear error to find the deputy’s difficulty with measurements was immaterial to his estimate of speed as that did not depend on time or distance. This finding rings in the absurd because one cannot discern a speed of a vehicle measured in miles-per-hour without discerning both the increment of distance traveled and the increment of time passed. The very definition of speed derives from the mathematical formula of distance divided by time. During the suppression hearing, the deputy exhibited a notable absence of fluency in his knowledge of distance measurements.

The reasonableness of an officer’s visual speed estimate depends, in the first instance, on whether a vehicle speed is estimated to be in significant excess or slight excess of the legal speed limit. If slight, then additional indicia of reliability are necessary to support the reasonableness of the officer’s visual estimate. The reasonableness of an officer’s visual estimate that a vehicle is traveling in slight excess of the legal speed limit may be supported by radar, pacing methods or other indicia of reliability that establish, in the totality of the circumstances, the reasonableness of the officer’s visual speed estimate. Such additional indicia need not require great exactions of time and mathematical skill that an officer may not have, but they do require some factual circumstance that supports a reasonable belief that a traffic violation has occurred.

Here, the deputy’s opinion was not supported by sufficient additional indicia of reliability. Standing alone, the deputy’s visual speed estimate – made at a speed differential of only 5 mph at a high rate of speed – did not provide the deputy with reasonably trustworthy information sufficient to warrant a prudent person in believing defendant had committed a speeding violation.

We conclude the deputy’s visual speed estimate was in fact a guess that was merely conclusory, without an appropriate factual foundation, and simply lacking in the necessary indicia of reliability to be an objectively reasonable basis for probable cause to initiate a traffic stop.

Reversed and remanded.


Traxler, J.: Today, we establish that a police officer cannot legally stop a speeding vehicle based only upon his visual estimate unless the vehicle is traveling in “significant excess” of the speed limit or the officer has the time and practical ability to confirm his belief that the vehicle is speeding through radar, pacing or some other corroborating evidence. While a lay person can estimate the speed of such a vehicle based on personal observation, an experienced and trained police officer no longer can.

I do not find the majority’s observations regarding the capabilities of law enforcement officers to be supported by the record. Moreover, I question how law enforcement officers, particularly those who have met their state certification requirements for visually estimating the speeds of vehicles within narrow margins of error, will know when they must forgo stopping a speeding vehicle unless and until they observe the vehicle cross into the “significantly speeding” category or they are able to obtain other, corroborating evidence.

I believe the majority’s adoption of the corroboration requirement for slight speeding violations has no place in the probable-cause context.

Neither the state-court conviction cases nor the unpublished probable-cause cases relied upon by the majority support its broad holding that an officer’s visual speed estimate can never suffice as a basis for an officer’s probable cause to initiate a traffic stop unless the suspect is estimated to be traveling in significant excess of the speed limit or the officer has the time and ability to corroborate his visual estimate through some other objective technique or circumstance. And the majority’s apparent basis for the rule — that the accuracy of human estimation of speed cannot easily, readily, and accurately discriminate between such small variations in speed — is not supported by the evidence in this case, which we must view in the light most favorable to the government.

I would affirm denial of the motion to suppress.

Top Legal News

See All Top Legal News


See All Commentary