When you’re pulled over for suspected DUI, you may be asked to step out of the car and perform what are known as field sobriety exercises. These are a series of physical and mental coordination tests that law enforcement officers use to determine if you’re impaired. But here’s the real question—do these field sobriety exercises hold up in court? The short answer: sometimes. Let’s take a deeper look at what these tests mean, how accurate they are, and how a criminal defense attorney can challenge them in court.
What Are Field Sobriety Exercises?
Field sobriety exercises—also known as field sobriety tests or FSEs—are used by police officers during a traffic stop when they suspect a driver is under the influence of alcohol or drugs. The three standardized tests recognized by the National Highway Traffic Safety Administration (NHTSA) are the Horizontal Gaze Nystagmus (HGN), the Walk-and-Turn (WAT), and the One-Leg Stand (OLS).
The HGN test involves tracking the movement of your eyes as you follow a stimulus, usually a pen or small flashlight. Officers look for involuntary jerking of the eyes, which can be a sign of alcohol impairment.
The Walk-and-Turn test requires you to walk in a straight line, heel-to-toe, then turn on one foot and return. It tests your balance, ability to follow instructions, and coordination.
Finally, the One-Leg Stand test has you lift one leg about six inches off the ground while counting aloud until told to stop. Officers are watching for swaying, hopping, or using arms for balance—things that might indicate intoxication.
These tests might seem simple, but their interpretation is subjective, and the results can have serious legal consequences.
How Accurate Are Field Sobriety Tests?
You might be surprised to learn that these exercises aren’t foolproof. According to a study conducted by the Southern California Research Institute and cited by the National Highway Traffic Safety Administration, the combined accuracy rate of the three standardized field sobriety tests when used together is about 91% for identifying individuals with a blood alcohol concentration (BAC) of 0.08 or higher.
Sounds pretty accurate, right? But let’s pump the brakes for a moment. That 91% figure is based on ideal conditions—controlled environments, highly trained officers, and compliant subjects. In the real world, things are a lot messier. Poor lighting, uneven ground, bad weather, nervous drivers, and even the shoes you’re wearing can impact how you perform.
Individually, the tests are less reliable. HGN is considered the most accurate of the three at around 88%, while the Walk-and-Turn and One-Leg Stand drop to 79% and 83%, respectively. Even sober people can fail these tests, especially if they have medical conditions, are older, or simply have poor balance.
How Officers Are Trained to Use Field Sobriety Exercises
Law enforcement officers receive specific training in administering FSEs during DUI investigations, typically as part of a Standardized Field Sobriety Test (SFST) certification course approved by NHTSA. This training includes classroom instruction and practical application, ensuring they follow a standardized procedure.
Officers are taught to observe not just whether you complete the task, but how you perform each part of it. Did you start too soon? Miss a heel-to-toe step? Sway while standing? These are all considered “clues” of impairment. However, this is where the line between science and subjective judgment begins to blur.
What many people don’t realize is that an officer’s interpretation of these tests can be influenced by unconscious bias or by confirmation bias—they may be expecting failure and therefore see it. A good criminal defense attorney will know how to question the quality of this training and whether the officer followed proper procedure.
Do Field Sobriety Tests Hold Up in Court?
Field sobriety tests are admissible in court, but their reliability can be challenged. In most jurisdictions, courts accept these tests as evidence of probable cause to arrest, but not as conclusive proof of intoxication.
Whether the tests hold up in court depends on how they were administered, documented, and whether the officer followed the standardized procedures. It also depends on how well the defense attorney can argue that other factors, like medical conditions, fatigue, or anxiety, may have affected the defendant’s performance.
For example, an officer might testify that a defendant failed the Walk-and-Turn test because they stepped off the line or didn’t turn properly. But in court, a skilled defense attorney might argue that the pavement was sloped, the lighting was poor, or the driver had a back injury that limited movement.
Courts have acknowledged these limitations. Some judges may even allow expert testimony from medical professionals or toxicologists to challenge the officer’s conclusions. So, while these tests can be used as part of the prosecution’s evidence, they’re not always ironclad.
Common Challenges to Field Sobriety Tests
There are numerous ways a criminal defense attorney can challenge the results of FSEs in court. One common approach is to highlight improper test administration. Officers who don’t follow NHTSA guidelines may introduce errors that make the results unreliable.
Another strategy involves pointing out non-alcohol-related explanations for poor performance. Conditions like vertigo, arthritis, anxiety, and even wearing high heels can skew results. A person’s weight, age, and physical fitness also play a huge role in how well they can perform the tests.
Attorneys may also question the officer’s credibility. Body cam footage can sometimes contradict an officer’s testimony, showing that the defendant’s performance wasn’t as bad as claimed. In other cases, it can show that the officer failed to clearly explain the instructions, making the test results invalid.
Lastly, if the officer didn’t have probable cause to stop the vehicle in the first place, everything that follows—including FSEs—could be suppressed.
Why You Need a Criminal Defense Attorney
If you’ve been arrested after a failed field sobriety test, you might think the evidence is stacked against you—but that’s not necessarily true. A criminal defense attorney who understands the science (and the flaws) behind field sobriety exercises can mount a powerful defense.
Your lawyer will analyze dashcam and bodycam footage, scrutinize police reports, and even bring in expert witnesses if needed. Their goal is to show that your test performance may have been influenced by factors unrelated to intoxication, and to highlight any missteps by the arresting officer.
Legal strategies may involve filing motions to suppress evidence, negotiating for reduced charges, or going to trial if the prosecution’s case is weak. Either way, your attorney’s role is to ensure your rights are protected and to fight for the best possible outcome.
Field Sobriety Tests Aren’t the Final Word
Field sobriety exercises can seem intimidating, and police may present them as objective science. But when it comes to holding up in court, there’s often room for reasonable doubt. These tests depend heavily on an officer’s subjective judgment and the circumstances under which they’re performed.
Just because you failed a field sobriety test doesn’t mean you’re guilty of DUI. With the right defense, you may be able to challenge the validity of the test, the officer’s procedures, or even the legality of the traffic stop itself.
Think You Failed a Field Sobriety Test? Don’t Panic—Call The Capetillo Law Firm.
The sooner you talk to a criminal defense attorney, the better your chances of building a strong defense. At Capetillo Law Firm, we understand how flawed and unreliable field sobriety tests can be—and we know how to fight back. If you’ve been arrested for DUI, let us help you protect your rights and your future.
Call now or schedule a free consultation to start your defense. You don’t have to face this alone.
