If you are stopped for suspicion of driving under the influence (DUI) the officer will likely offer you field sobriety tests. These tests are supposed to measure a driver’s physical coordination and ability to follow instructions to see if they’re impaired by alcohol or drugs. Field sobriety tests are used in DUI cases all the time, but how accurate are they? And more importantly, what do they mean for you if you’re facing DUI charges?
In this article we’ll look at the accuracy of field sobriety tests, the potential for mistakes and how these tests impact DUI cases. Knowing these factors will help you make informed decisions and protect your rights if you’re ever stopped for suspicion of DUI in Colorado or anywhere else.
What are Field Sobriety Tests?
Field sobriety tests are standardized physical tests given by police officers during a traffic stop when they suspect a driver may be under the influence of alcohol or drugs. The most common tests are part of the Standardized Field Sobriety Test (SFST) battery which includes three main exercises:
- The Horizontal Gaze Nystagmus (HGN) Test: This test involves following a moving object (usually a pen or flashlight) with your eyes. The officer is looking for involuntary jerking movements of the eyes (nystagmus) which can be a sign of intoxication.
- The Walk-and-Turn Test: The driver is asked to take 9 steps, heel to toe, in a straight line, turn around and take 9 steps back. The officer is looking for balance, coordination and ability to follow instructions.
- The One-Leg Stand Test: The driver is asked to stand on one leg for a period of time while counting out loud. The officer is looking for swaying, hopping or using arms for balance, all of which can be a sign of impairment.
These tests are supposed to help police officers make an objective determination of impairment. But the reliability of these tests is often questioned in legal cases.
Are Field Sobriety Tests Accurate?
The short answer is: no. While field sobriety tests are standardized and widely used, they’re not foolproof. Several factors can affect the accuracy of these tests resulting in false positives (indicating impairment when there isn’t any) or false negatives (failing to identify impairment).
1. Physical and Medical Conditions
One of the main reasons field sobriety tests are unreliable is because they rely on a person’s physical abilities. Many medical conditions can mimic the signs of impairment and cause a driver to fail a test even when they’re sober. For example:
- Inner ear problems can affect balance and make it hard to do the one-leg stand or walk-and-turn test.
- Neurological conditions or old injuries can affect coordination.
- Age and general physical fitness can play a major part.
Fatigue, anxiety or nervousness during a traffic stop can cause poor performance. In DUI cases these factors can create the illusion that the driver is intoxicated even if they’re not.
2. Environmental Factors
The environment where the test is given can also affect the accuracy of field sobriety tests. If the test is given on uneven ground, in bad weather or with distractions (like traffic noise or bright lights) it’s hard for anyone to do well.
For example, trying to walk heel to toe on an inclined or gravel surface is much harder than on a smooth flat road. Standing on one leg for an extended period is harder in cold or windy weather especially if you’re not dressed for the conditions. These environmental factors can skew the results of the test and result in unfair DUI charges.
3. Officer Subjectivity
Field sobriety tests are subjective. While the tests themselves are standardized the interpretation of the results is up to the police officer administering them. This can introduce bias or human error into the process.
For example, one officer may see a slight sway on the one-leg stand as a failure while another officer may see the same amount of sway as passing. If an officer is already convinced the driver is impaired before the test begins they may be more likely to see and report signs of impairment even if they’re minimal or unrelated to alcohol or drug use.
This subjectivity makes field sobriety tests less reliable than more objective tests like breathalyzers or blood tests.
Legal Ramifications of Field Sobriety Tests
If you’ve been arrested for DUI based on the results of a field sobriety test the reliability of the test can be used in your defense. Here are a few ways field sobriety tests can affect a DUI case:
1. Challenging the Results in Court
An experienced DUI defense attorney can challenge the results of field sobriety tests in court. Since these tests are not always reliable an attorney can argue that medical conditions, environmental conditions or officer subjectivity caused an inaccurate assessment of impairment. If the court agrees it may throw out the results of the field sobriety test and weaken the prosecution’s case.
Additionally, if the officer didn’t follow the standardized procedures for the test the results may be inadmissible in court. Police officers are trained to follow specific protocols when doing field sobriety tests and any deviation from those procedures can invalidate the results.
2. Supplementing with Other Evidence
Field sobriety tests are often just one piece of evidence in a DUI case. Other evidence like breathalyzer or blood test results, dashcam footage and witness testimony can also be used. If the field sobriety test results are weak or questionable the prosecution may rely more on this other evidence to get a conviction.
In some cases, the lack of reliable field sobriety test results can result in reduced charges or even case dismissal if other evidence is weak as well.
3. Refusing Field Sobriety Tests
In Colorado you are not required to take a field sobriety test. Unlike chemical tests (like breathalyzer or blood tests) which are under Colorado’s express consent law field sobriety tests are voluntary. If an officer asks you to do one of these tests you can say “no”.
If you decide to refuse a field sobriety test you need to know your rights and understand how it will affect your case. In most cases it’s better to refuse the test as it limits the amount of subjective evidence the prosecution can use against you. However, this decision should be made carefully.
Conclusion: Are Field Sobriety Tests Reliable?
Field sobriety tests are a common tool in DUI investigations but they’re far from perfect. There are many factors that can affect their reliability from medical conditions and environmental influences to officer subjectivity and improper administration. That raises big questions about the fairness and accuracy of a DUI charge based solely or mostly on field sobriety test results.
If you’ve been charged with a DUI in Colorado based on field sobriety tests you need to talk to an experienced criminal defense attorney who knows the flaws in those tests and can attack them in court. With the right legal strategy, you can fight for a fair result and protect your rights.
In the meantime, if you get pulled over for a DUI remember you don’t have to take a field sobriety test. Knowing your rights and understanding the limitations of those tests will help you make smart decisions in a high-pressure situation.