If you were pulled over for suspected DUI in Pennsylvania and asked to perform a field sobriety test, your physical condition matters. Injuries—whether recent or long-standing—can directly affect your ability to complete these tests and may lead to misleading results that suggest impairment when none exists.
At Fienman Defense, our Philadelphia DUI defense attorneys have seen how physical limitations can distort DUI cases. Understanding how injuries interfere with standardized field sobriety tests can be critical to building your defense and protecting your rights.
What Are Field Sobriety Tests?
Field sobriety tests (FSTs) are physical tasks law enforcement officers use to assess impairment during a DUI stop. The most common tests are part of the National Highway Traffic Safety Administration’s (NHTSA) Standardized Field Sobriety Test (SFST) battery, which includes:
- Horizontal Gaze Nystagmus (HGN)
- Walk-and-Turn
- One-Leg Stand
These tests are often introduced as objective indicators of intoxication, but they require coordination, balance, and neurological function. That’s where injuries can complicate the picture.
How Different Injuries Affect Each Field Sobriety Test
1. Horizontal Gaze Nystagmus (Eye Tracking)
In this test, an officer asks you to follow an object side-to-side with your eyes. They’re looking for involuntary eye jerking—a phenomenon that becomes more pronounced when someone is impaired.
Injury Impact: If you’ve ever sustained a concussion, traumatic brain injury (TBI), or suffer from vertigo, your eye movements may already be abnormal. Medications, fatigue, or neurological disorders can also influence results—raising the risk of a false positive.
2. Walk-and-Turn Test
You’re asked to take nine heel-to-toe steps in a straight line, pivot, and return. The officer watches for signs of imbalance, poor coordination, or failure to follow instructions.
Injury Impact: Individuals with knee injuries, ankle sprains, hip replacements, or lower back problems often struggle with this test, even when sober. Chronic pain, muscle weakness, or recent surgery may prevent compliance with instructions and increase perceived “clues” of impairment.
3. One-Leg Stand Test
This requires you to stand on one leg for 30 seconds while counting aloud. It’s meant to test balance and divided attention.
Injury Impact: This test is difficult even for many healthy adults. If you have a leg injury, inner ear condition, sciatica, or balance disorder, your results may be skewed. Previous surgeries or physical therapy limitations can also affect your ability to stay balanced.
What To Do If You Have a Physical Injury
If you are asked to take a series of field sobriety tests and you recognize that you have a physical injury that could impact your ability to take the tests successfully, it is important to inform the officer of your injury history before you begin taking any field tests. The officer may insist that you take the tests regardless, but you will have established a reason completely unrelated to intoxication that could affect your performance. If you are charged with a DUI and choose to fight your charges this could be an important factor in your DUI defense.
Why These Details Matter in DUI Defense
Field sobriety tests are subjective. An officer’s interpretation may be influenced by confirmation bias, especially during nighttime stops. If you’re arrested and charged with DUI based on these tests, an experienced DUI lawyer can:
- Challenge the validity of the field sobriety results
- Request medical records or expert testimony on your physical condition
- Argue that the officer lacked probable cause based on flawed or biased testing
What Injuries Can Affect Field Sobriety Tests?
Common injuries that impact performance include leg, knee, ankle, or back injuries, concussions or traumatic brain injuries, vertigo, and neurological disorders. These can influence balance, coordination, and eye movement—key elements of the tests.
Should I Tell the Officer About My Injury?
Yes, always inform the officer of any injury or medical condition that could interfere with the test. Clearly stating your limitations before testing begins helps preserve your defense and can prevent false interpretations of impairment.
Can I Be Arrested Even If My Injury Affected the Test?
Yes, officers may still make an arrest based on their interpretation of the situation. However, a skilled DUI defense attorney can argue that the arrest lacked probable cause due to your physical limitations and challenge the admissibility of test results in court.
Do Injuries Count as a Legal Defense in a DUI Case?
Documented physical injuries—like joint damage, neurological conditions, or balance disorders—can be used to challenge the reliability of field sobriety test results. An experienced DUI lawyer can use your medical history to dispute probable cause for arrest.
Contact Fienman Defense Today
Field sobriety tests are an important tool for law enforcement and are used as evidence in the prosecution of DUI cases. However, even the most accurate of field sobriety tests can lead to the incorrect result over 10 percent of the time. If you have a physical injury the chance of an incorrect result in field sobriety tests could soar much higher. So if you are facing a DUI charge that is based in part on a field sobriety test you want an experienced Philadelphia criminal defense attorney to aid in your defense.
Call Philadelphia DUI lawyer Michael Fienman at (215) 839-9529 to see how he can help you obtain the best possible result for your case.
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