DUI Info: Part II

In this post, I tried to provide a basic understanding of a DUI incident.  In Part II, I will focus specifically on the voluntary field sobriety evaluations.


Please note that I referred to them as both as voluntary and as evaluations.  By voluntary I mean just that.  A driver has no obligation to perform the evaluations.  Failure to do so is not an indicator of intoxication.  In fact, some people will not be able to do them due to medical screening issues built into the evaluations.  As for the term evaluations, they are commonly termed as “tests”, but this is not accurate as “tests” indicates that they are on a pass/fail basis, which is not correct.  They are an evaluation tool that allows the peace officer to make a determination based on the totality of the circumstances.

The actual correct term for the evaluations is Standardized Field Sobriety Evaluations (SFSE) with emphasis on the “standardized”. The evaluations, at least the standardized version of them, are scientifically proven and accepted. They should be completed in the prescribed order. There are only three SFSEs. They are the Horizontal Gaze Nystagmus, Walk and Turn, and One Leg Stand. Any evaluation used other than those three are non-standard. A peace officer must successfully complete a training course to be certified to conduct the standardized evaluations.

Nystagmus is an involuntary jittery or twitching eye movement. While some nystagmus may be natural, it is readily induced by alcoholic beverages and some drugs. As it is not a voluntary movement, it is not able to be controlled by the individual; so, it is a very telling evaluation. It does require several medical screenings for the evaluation to be valid. For instance, a person who does not have equal pupil size or their eyes do not track equally is medically screened out from participating in this evaluation. Nystagmus is checked for by passing a stimulus back and forth at a distance of 12 to 18 inches from the eyes. The first several passes are to conduct the medical screenings. The rest are to check for smooth pursuit, nystagmus at maximum deviation, and the onset of nystagmus at prior to a 45 degree angle of the eyes. As for smooth pursuit, the eyes should smoothly follow the stimulus as it moves back and forth and not exhibit jerking movements, which are an indicator of intoxication. As for maximum deviation, an intoxicated person is likely to show sustained and distinct nystagmus as the stimulus is held at the furthest point of the back and forth passing of the stimulus. Finally, the onset of nystagmus prior to the eyes reaching a 45 degree angle when following the stimulus. Vertical nystagmus is also checked, but vertical nystagmus is not an indicator of drugs as is commonly believed. It is an indicator of a high intoxicant level for the particular person.  Training for what to look for in the eyes is conducted through the use of videos of the eyes of people at various intoxication levels.  The use of live drinkers is now discouraged for this training.

The Walk and Turn evaluation is an evaluation of both a person’s ability to follow directions as well as their ability to walk in a straight line and maintain their balance. Obviously, there are medical conditions that could prevent a person from being able to complete this evaluation; so, it is important for the officer to ask good screening questions. The exercise should be demonstrated by the officer prior to the driver participating. Of note here, I have bad ankles due to a chronic medical condition as well as an injured knee. Prior to demonstrating this evaluation, I always informed/inform the driver of this so that they had a better perspective of the evaluation and the physical ability needed to do complete it. This evaluation involves the participant beginning from a prescribed position, taking nine steps touching heel to toe with each step, turning in a prescribed and demonstrated manner, and then taking nine heel to toe steps back to the starting point. The line walked should be straight with the participant’s arms by their side and with their eyes watching their feet as they walk. The officer is looking to see if the driver steps off line, fails to touch heel to toe with each step, and whether or not the driver raises their arms from their side to maintain their balance.

The One Leg Stand evaluation involves the driver raising one foot approximately six inches off of the ground and with the toe pointed. Their arms should be at their side, their support leg should be locked at the knee, and their eyes should be focused on the toe of their extended foot. Like the Walk and Turn, there are medical/physical conditions that could legitimately prevent a person from being able to participate in the evaluation. In this evaluation, the officer watches to see if the driver is able to maintain their balance without hopping or swaying and without touching their foot back to the ground.

The above are the standardized evaluations and they should be completed in the order as described. There is no pass/fail point at which a person is declared intoxicated to the point of being DUI or not. The officer makes a determination based upon everything observed during the contact to include slurred speech, the odor of an alcoholic beverage on the driver’s breath, and their coherence, appearance and demeanor. Again, they are completely voluntary. If a driver chooses not to participate, the peace officer must make a determination at that point whether or not to proceed with an arrest. I do not have statistics to reflect any specific percentage as to how many times I made an arrest after conducting the exercises versus letting a person go. The latter category would be the higher percentage.

There are many non-standard evaluations that can also be used. There is a myth that just will not be put to rest when it comes to one of these. Whether or not a person can say the alphabet backwards is not an indicator of intoxication. I do not know how many times when asking a person if they would participate in voluntary SFSEs tell me that they would do so but they wanted to let me know up front that they could not say the alphabet backwards. I usually try to keep a straight face and say something along the lines of, “Okay, we’ll skip that one then.” I did/do commonly ask people to say (not sing) the alphabet. I never had a person mess up the alphabet that did not provide a considerably high blood alcohol content sample. Of course, in order for this evaluation to have any merit, it must be established that the person in question knows the alphabet. I did have one occasion when a Columbian national stated that he did not know the alphabet in English. I hope that Mrs. Bailey would be proud to know that many years after high school Spanish class that I still remembered the Spanish alphabet and was able to complete the evaluation.

Click here to see a form that we use when conducting SFSEs to help ensure that the evaluations are done correctly.  It accompanies a DUI arrest report.
I hope that the above helped provide you with a clearer picture of field sobriety evaluations.  It is a difficult topic to tackle without getting into the minutia of the details, and some aspects of the topic just do not easily translate into text.