Can Anxiety or Medical Conditions Affect Sobriety Test Performance?

Yes. Anxiety, physical limitations, and certain medical conditions can all impact a person’s ability to perform field sobriety tests. In some cases, these factors may even produce signs that could be mistaken for impairment. While they do not automatically invalidate a test, they can still influence the results and become important considerations in a DWI case.

In busy metropolitan areas like Houston, where extensive highway systems and active law enforcement contribute to frequent DWI investigations, field sobriety tests are a common part of roadside procedures. However, it is important to recognize that these tests must be properly administered, and various external factors can affect their accuracy.

Because of this, when questions arise about the validity of field sobriety testing, a seasoned DWI defense lawyer in Houston can review whether anxiety, medical issues, or testing conditions may have played a role in the results.

What Do Field Sobriety Tests Measure?

The standardized Field Sobriety Tests (SFSTs) assess balance, coordination, attention, and direction.

There are three NHTSA-recommended tests:

1. Horizontal Gaze Nystagmus (HGN)
2. Walk-and-Turn
3. One-Leg Stand

These tests are used to assess if there is evidence of impairment but are not foolproof tests for intoxication.

In What Ways Can Anxiety Impact Test Performance?

An increasing number of people get tense when a police officer pulls them over. Physical responses to stress can manifest themselves as impairment.

Examples include:

• Shaking hands or legs
• Difficulty concentrating
• Difficulty with complex directions
• Rapid breathing
• Tension-induced loss of balance

Anxiety does not lead to intoxication but can impair performance on tests of balance and coordination. In certain instances, an officer may consider the above behaviors as evidence of impairment in the absence of other factors.

What Are Some Medical Conditions That May Affect Sobriety Testing?

Field sobriety tests may be more challenging due to certain medical conditions, even if the driver is totally sober.

Common examples include:

• Inner ear disorders
• Dizziness and instability of balance.
• Neurological conditions
• Any injuries to the knees, ankles, or back.
• Multiple sclerosis
• Vision disorders

Medical Conditions That May Affect Results

NHTSA training materials recognize that physical conditions that can impact balance, walking, vision, or coordination will impact test performance.

Is it the ecological factors that matter or not?

They often do.

• A normal, nonintoxicated person might have trouble taking tests on the following:
• Uneven pavement
• Gravel shoulders
• Sloped roadways
• Wet surfaces
• Poorly lit areas

The NHTSA notes in its materials that the conditions on the road are not always ideal and can impact the value of test results.

Legal Considerations in DWI Cases

The Texas DWI statute is typically found in the Texas Penal Code § 49.04 in Texas. Field sobriety tests may play a role in probable cause for arrest, but courts will consider the impact of medical or anxiety issues or improper testing procedures.

Attorneys for the defense will typically check:

1. Medical records
2. Body camera footage
3. Officer training records
4. Road and weather conditions
5. Test administration procedures

The information can be useful to assess whether performance was impaired or not.

Key Takeaways

• Field sobriety test performance may be adversely affected by anxiety.
• Signs may be similar to those of impairment caused by medical conditions.
• Common problems include balance disorders, injuries, and neurological issues.
• The conditions along the road and the weather may have an impact on the test results.
• The field sobriety tests are investigative tools and not a conclusive test of intoxication.
• Medical or environmental issues can be a challenge in Texas DWI cases.
• The overall context of the stop can be more important than the test.