The NHTSA DWI Detection and Standardized Field Sobriety Testing Manual has a chapter devoted to “DWI Detection Phase One: Vehicle in Motion”. A list of 24 driving cues which “police officers may use to detect nighttime impaired drivers” is the meat of the chapter.
These same 24 cues are also listed in NHTSA’s booklet “The Visual Detection of DWI Motorists”. The chapter in the manual breaks these driving behaviors, most of which but not all are traffic violations, into four separate categories:
- Problems Maintaining Proper Lane Position
- Speed and Braking Problems
- Vigilance Problems
- Judgment Problems
The second part of Phase One: Vehicle in Motion is entitled “The Stopping Sequence”. In it, the officer is told to look for how the vehicle responds to the signal to stop (which will almost always be the activation of police overheads). Cues include:
- an attempt to flee
- no response
- slow response
- an abrupt swerve
- sudden stop, and
- striking the curb or another object
In most cases, while my client will probably be spotted initially committing a traffic violation, which may be included in the first 24 driving behaviors, the vast majority of times they exhibit none of the stopping sequence cues.
Absence of these cues, of course, does not prove the absence of intoxication. But, the defense is not required to prove innocence. Secondly, pointing out that all of these behaviors commonly associated with the typical intoxicated driver do not apply to my client can be useful for cross examination of the stopping officer.
[For those interested, The Visual Detection of DWI Motorists is available free of charge in booklet form upon request to: National Highway Traffic Safety Administration – Impaired Driver Division, 400 Seventh Street, SW., Room 5118, Washington D.C., 20590.]