Officers attending the NHTSA DWI/SFST student course are taught to recognize, document, and testify to 24 validated driving cues prior to the command to stop during Phase I, Vehicle In Motion. These driving cues are based on the NHTSA study entitled, “The Visual Detection of DWI Motorists” (DOT HS 808 677), which is available in our members only virtual library.
In this study, the 24 driving cues are broken into four different categories with each category having its own percentage predicting if a driver is DWI. These percentages range from 90% to 35%, based on a driver displaying just one of these driving cues (2018 revision, session 5, pages 4-7). One important component to these percentages that some officers are not taught or tend to forget is according to the NHTSA study, these percentages apply to nighttime driving only.
Why is the “nighttime driving only” component sometimes not taught by the SFST instructor or easily forgotten by the student? Simple answer – the NHTSA student manual itself. Prior to the 2013 revision of the NHTSA student manual, the manual was noticeably clear that the percentages only applied to nighttime driving. When the 2013 revision was released, whether by accident or intentional, “nighttime driving” was removed. It was not put back in the 2015 revision and it was not put back in the most current revision, 2018.
Why is this significant? It all comes down to the officer being able to testify to the phrase “validated cue based on a NHTSA study” or to a percentage rate of the driver being DWI based on a NHTSA study. Weaving is weaving, whether during the day or at night. But if a driver is stopped for weaving at 2:00pm, the 50%-75% probability that the driver is DWI just based on that driving act does not apply nor does the phrase “NHTSA validated driving cue”.
Additionally, the student manual has a description of each of the validated driving cues. Surprisingly (at least to me), I have heard several officers testify to a driving characteristic they felt was a specific NHTSA driving cue that ended up not even matching the description of the cue in the manual. Riddle me this….. how are you, the judge, and the jurors supposed to believe in the officer’s ability to correctly interpret Personal Contact cues or the SFST clues when the officer cannot even correctly categorize driving cues?