Being told you “failed” the roadside tests in Arapahoe County can make it feel like your DUI case is already lost. You might be replaying the traffic stop in your head, remembering the flashing lights, standing on the shoulder, and trying to follow instructions while cars flew by. Then the officer said you showed “clues of impairment,” and everything changed from a traffic stop to handcuffs and a ride to the jail.
In the middle of that shock, no one explains that those field sobriety tests have built-in limits and a significant field sobriety test error rate. No one tells you that the numbers officers are trained on come from controlled studies that look very different from the side of a dark road in Arapahoe County. You are left with the painful impression that if you did not perform perfectly, the tests must be right and you must be guilty.
I know how heavy that feels because I have reviewed and challenged field sobriety tests in a large number of Colorado criminal cases, including many in Arapahoe County. I work with the same National Highway Traffic Safety Administration (NHTSA) Standardized Field Sobriety Test manuals that officers are supposed to follow, and I see how often real-world practice drifts away from what the science actually supports. In this article, I want to pull back the curtain on how unapproved field sobriety test variations and protocol errors can create false positives, and how I use those problems to defend people just like you.
To talk about what happened in your stop in Arapahoe County and what can be done about it, call for a free consultation today. Call me at (720) 809-8262.
Why Field Sobriety Tests Are Only “Accurate” On Paper
Field sobriety tests sound scientific because officers refer to them as “standardized” and sometimes mention accuracy percentages from NHTSA research. The three tests that make up the Standardized Field Sobriety Test battery are the Horizontal Gaze Nystagmus test, the walk and turn, and the one leg stand. In controlled studies, when these tests are administered exactly as designed, NHTSA has found that officers can correctly identify a significant percentage of drivers who are above the legal limit. Those studies are the foundation for the training Colorado officers receive.
That research, however, comes with very clear conditions. The reported accuracy rates assume that the officer uses the exact NHTSA wording, demonstrates the test properly, uses the correct timing, and scores only the specific “clues” the manual describes. The studies also assume relatively good conditions, such as flat, dry surfaces and cooperative subjects who clearly understand the instructions. When all of that lines up, the field sobriety test error rate can be relatively low for the population studied.
On the side of Arapahoe Road or I-25, those ideal conditions rarely exist. Drivers are nervous, traffic is loud, shoulders may be sloped or icy, and instructions are often rushed. In those circumstances, the tidy accuracy numbers from the NHTSA studies do not apply, because the test has stopped being the same test. The label “standardized” still appears in the report, but the underlying procedure has been changed in small but important ways that push the field sobriety test error rate higher than the paperwork suggests.
When I review a DUI case, I start from this basic reality. I do not assume that a “fail” on the walk and turn or one leg stand proves impairment. I compare what the officer actually did and said, on body cam and dash cam, against the step by step requirements in the NHTSA manual. Very often, the test the officer performed in Arapahoe County is quite different from the test that generated the comfortable accuracy numbers in the NHTSA studies.
Common Officer Deviations That Inflate Field Sobriety Test Error
In theory, every officer in Arapahoe County has been trained to deliver identical field sobriety tests. In practice, each officer develops habits, shortcuts, and personal variations over time. These may not sound dramatic when you read the report, but they can have a big impact on whether a sober or borderline driver appears to “fail.” Understanding these common deviations is one of the keys to understanding field sobriety test error.
One of the biggest problems I see is rushed or incomplete instructions. The NHTSA walk and turn, for example, has a detailed instruction phase. The officer is supposed to show you the stance, explain the heel to toe steps, count out loud, and make sure you understand before you start. Under real roadside time pressure, officers often shorten this sequence or blend steps together. A driver who is trying to process traffic, cold, fear, and unfamiliar instructions at the same time can easily miss one part, then get scored for “starting too soon” or “improper turn,” even though the confusion came from poor instruction, not alcohol.
I also see timing and counting errors on the one leg stand. The manual calls for a specific count, roughly 30 seconds, while the officer watches for swaying, hopping, or putting the foot down. Some officers cut that short, or they keep counting in their head while the driver thinks the test is over. Others treat tiny, normal balance adjustments as major “clues.” What looks like objective scoring on paper is often a very subjective judgment that becomes less reliable as officers drift away from the exact NHTSA framework.
Environmental conditions turn small deviations into big problems. The NHTSA materials assume a reasonably level, dry, non-slippery surface. In Arapahoe County, tests often happen on sloped shoulders, gravel, wet pavement, or in stiff wind from passing trucks. Headlights, flashing light bars, and uneven lighting affect how the eyes track during the Horizontal Gaze Nystagmus test. When these factors are not controlled, or at least noted and adjusted for, they introduce field sobriety test error that has nothing to do with alcohol but everything to do with where and how the test was given.
In many of the cases I handle, the report contains a single line claiming the tests were done “per training.” The video tells a different story. Because I have studied the NHTSA standards and seen how they look on proper demonstration, I can spot where an Arapahoe County officer skipped a step, added a twist, or ignored a hazard. Those deviations are not technicalities. They are reasons why the claimed accuracy of the test no longer applies to your situation.
Unapproved Test Variations & Non-Standard Exercises
Another common source of field sobriety test error comes from something NHTSA itself warns against, improvising or substituting non-standard exercises. Officers in the real world often add tests that are not part of the validated SFST battery. These may include having you recite part of the alphabet, count backwards, touch your nose with alternated fingers, or follow complicated instructions that were never studied for accuracy in predicting blood alcohol content.
These extra tests usually sound harmless in the report. The officer may simply say that you had difficulty with the alphabet or miscounted by a number or two. In court, that can be described as another sign of impairment. The problem is that there is no solid research showing how often sober, anxious drivers make those same mistakes under stress. The more an officer relies on unapproved tests, the further they get from the limited science NHTSA actually offers.
Non-standard exercises are also scored very subjectively. With the walk and turn and one leg stand, NHTSA defines a small set of specific clues, such as stepping off the line, using arms for balance, or putting the foot down. There is a framework for how many clues suggest impairment. With improvised alphabet or finger tests, officers usually do not have a fixed scoring system. They simply conclude that the performance “appeared impaired” and add that to the probable cause narrative. That kind of open-ended judgment creates room for bias and increases the field sobriety test error rate.
In my practice, I make a point of identifying any non-standard exercises the officer used in your Arapahoe County stop. I compare them to what the NHTSA manual actually recommends and flag them as unvalidated tools when I speak with prosecutors or the court. When the state wants to lean on the authority of “standardized tests,” it is important to show where the officer stepped outside that framework and relied on personal improvisation instead of science.
How Medical Conditions and Normal Human Limits Mimic “Clues of Impairment”
Even when an officer follows the NHTSA script more closely, field sobriety test error can still be high because the tests assume a certain level of physical ability and do not always account for individual differences. Many people in Arapahoe County who are completely sober would struggle to perform a perfect heel to toe walk on a good day, let alone at night on the side of a highway. Age, weight, prior injuries, and general fitness all play a role in how someone looks while performing balance and coordination tests.
Medical conditions can have an even bigger impact. Inner ear problems, neuropathy, knee or ankle injuries, and back pain can make the walk and turn or one leg stand very difficult, especially when you are holding an unnatural stance with your arms at your sides. Neurological conditions or certain medications can cause involuntary eye movements or difficulty focusing, which may look like Horizontal Gaze Nystagmus to an officer who is not a doctor. Fatigue and low blood sugar can affect concentration and balance in ways that overlap with the signs officers are trained to interpret as alcohol-related.
NHTSA training materials do acknowledge that some people simply are not good candidates for certain tests. Older drivers, people with physical disabilities, those who are significantly overweight, and people wearing certain shoes can be poor fits for balance-based evaluations. In theory, officers are supposed to take that into account. In practice, I regularly see Arapahoe County cases where these limitations are either ignored or quickly brushed aside, and the driver’s difficulty is written up as “failing” rather than as a predictable reaction to their condition.
When I review a DUI case, I ask detailed questions about prior injuries, surgeries, chronic conditions, and medications. If needed, I work with physicians or obtain medical records to document why a client might show certain “clues” on field sobriety tests that have nothing to do with drinking. That documentation can be very powerful in court or negotiations, because it replaces a vague suggestion of impairment with a concrete, medically supported explanation for what the officer saw on the roadside.
Workflow Shortcuts in Arapahoe County DUI Stops
Many breakdowns in field sobriety testing are not the result of a single bad officer. They come from workflow shortcuts that develop over time within a department. In Arapahoe County, officers often have to move quickly to clear traffic, respond to other calls, and work within shift constraints. Under that kind of pressure, it is easy for small steps in the NHTSA procedure to be dropped or condensed without much thought.
For example, I see many stops where the officer chooses the first available space to conduct tests, even if the shoulder is sloped or covered in gravel. From a traffic-control standpoint, that may feel efficient. From a scientific standpoint, it undermines the assumptions behind the walk and turn and one leg stand. In colder months, I see tests performed on icy or wet surfaces around Greenwood Village and other parts of Arapahoe County, which clearly affects balance but rarely appears as a meaningful factor in the report.
Time pressure also feeds report-writing habits. Rather than documenting every instruction and observation in detail, many officers rely on boilerplate language that says the tests were done “in accordance with training” and that the subject exhibited a set number of “clues.” When I compare that language with body cam footage, I often find that key parts of the NHTSA procedure were rushed or omitted. The workflow encourages quick, standardized narratives, but the actual testing is less standardized than the paperwork suggests.
Because I have handled a large volume of cases in Arapahoe County and other Colorado jurisdictions, I can spot these patterns across departments. I know what a truly standardized test looks like, and I know the kinds of shortcuts that tend to show up on the roadside. That experience lets me separate an honest, carefully administered test from one that has been shaped by workflow demands in ways that increase field sobriety test error and weaken the state’s probable cause argument.
How I Use Field Sobriety Test Error To Challenge DUI Charges
Understanding where field sobriety tests break down is only half the picture. The other half is how to turn those problems into leverage in your DUI case. In every Arapahoe County DUI I handle, I personally review the police report, body cam, and dash cam footage with the NHTSA manual in mind. I do not assume that the officer’s summary is accurate. I check whether each instruction was given, whether the demonstrations were correct, and whether the conditions were suitable for the tests used.
Once I have identified specific deviations, I connect them to the concept of probable cause. Colorado officers often rely heavily on field sobriety tests to justify a DUI arrest. If the tests were not true standardized SFSTs, their conclusions about impairment rest on a weak foundation. I use that to challenge whether the arrest was properly supported and to argue that the field sobriety test error rate in this particular case is too high to treat those results as reliable evidence of intoxication.
In the courtroom, this can play out in several ways. I may file motions that ask the judge to limit or exclude the field sobriety evidence because of unapproved variations or poor conditions. I may use cross examination to walk the officer through each step they skipped or each non-standard test they added, highlighting the gap between their training and their actual practice. In negotiations with Arapahoe County prosecutors, a documented pattern of errors can make them more open to reducing or resolving charges in ways they might not consider if the tests appeared clean on paper.
Because I do not delegate this analysis to associates or paralegals, my clients know that the same person who explains these SFST issues here is the one dissecting their own stop. When appropriate, I bring in investigators to photograph or measure the test location, or consult with medical professionals to explain why a client’s performance would look impaired even if their driving was not affected by alcohol. All of that work is aimed at one goal, giving the court a more accurate picture of what those field sobriety tests do and do not prove.
What You Can Do Right Now If You “Failed” Field Sobriety Tests
If you were told you failed field sobriety tests in Arapahoe County, the worst thing you can do is assume that your case is hopeless. The officer’s opinion is only one piece of evidence, and as you have seen, that opinion often rests on tests that were changed, rushed, or given under poor conditions. A key part of protecting yourself is making sure someone who understands both the law and the science reviews what actually happened as soon as possible.
Acting quickly matters because some of the most important evidence does not last forever. Dash cam and body cam recordings may only be kept for a limited time. Roadside conditions can change, especially with Colorado’s weather. Memories fade, and medical issues that affected your performance may be harder to document later. Preserving that evidence while it is still fresh gives me more to work with when challenging the field sobriety test error in your case.
Talk To A Lawyer Who Knows How To Expose Field Sobriety Test Error
Field sobriety tests carry a lot of weight in DUI arrests, but they are not the final word on whether you were actually impaired. In Arapahoe County, unapproved test variations, rushed instructions, poor testing locations, and overlooked medical issues regularly push the field sobriety test error rate beyond what NHTSA’s research would suggest. When those problems are documented and explained clearly, they can change how judges, juries, and prosecutors view your case.
If you are facing a DUI charge after an officer said you failed field sobriety tests, you do not have to face that alone or simply accept the officer’s version of events. I personally review the testing in every case I take, comparing what happened on the roadside to the standards officers are supposed to follow and using my experience across a large number of criminal cases to build a strategy that fits your situation.
To talk about what happened in your stop in Arapahoe County and what can be done about it, call for a free consultation today. Call me at (720) 809-8262.