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  • Writer's pictureBrian Foley

Houston DWI Attorney - Cross Examining a Police Officer on Field Sobriety Tests

Houston DWI Attorney Brian Foley is board certified in criminal law and was a member of the vehicular crimes team focusing on DWI offenses.

When facing a DWI charge in Houston, having a skilled and knowledgeable attorney by your side can make all the difference in the outcome of your case. One crucial aspect of defending against DWI charges is understanding how to effectively cross-examine a police officer on the standardized field sobriety tests (SFSTs). In this blog post, we will focus on three primary SFSTs - the Horizontal Gaze Nystagmus (HGN), Walk and Turn, and One Leg Stand tests - and provide insights on how a Houston DWI attorney can challenge the results during cross-examination.

  1. The Importance of Standardized Field Sobriety Tests

Standardized Field Sobriety Tests are a battery of tests used by law enforcement officers to determine if a driver is under the influence of alcohol or drugs. While they are intended to be objective measures of impairment, they can often be influenced by various factors, such as medical conditions, nervousness, fatigue, or improper administration by the officer.

  1. Understanding the Three Primary SFSTs

a. Horizontal Gaze Nystagmus (HGN) Test:

The HGN test measures the involuntary jerking of the eyes. An impaired person may exhibit more pronounced nystagmus. To effectively cross-examine the police officer on this test, the defense attorney should focus on:

  • The officer's training and experience in administering the test.

  • The officer's positioning of the suspect during the test and whether it was conducted in a well-lit area.

  • Any potential medical conditions that may cause nystagmus, unrelated to alcohol or drug impairment.

  • The accuracy of the officer's observations and whether they noted other potential signs of impairment.

b. Walk and Turn Test:

In this test, the suspect is asked to take nine steps in a straight line, heel-to-toe, turn, and take nine steps back. Key points for cross-examination include:

  • The officer's instructions to the suspect and whether they were clear and understandable.

  • Any physical conditions that might have affected the suspect's ability to perform the test accurately.

  • The surface on which the test was conducted, as uneven or slippery surfaces can impact performance.

  • Whether the suspect demonstrated any other signs of impairment, such as slurred speech or bloodshot eyes.

c. One Leg Stand Test:

During this test, the suspect is asked to stand on one leg while counting aloud for about 30 seconds. Cross-examination on this test should address:

  • The officer's training and proficiency in administering the test.

  • Whether the suspect was given clear and proper instructions.

  • Any medical conditions or physical limitations that might have affected the suspect's ability to balance.

  • The presence of other signs of impairment that were or were not observed by the officer.

  1. Challenging the Officer's Observations

An experienced Houston DWI attorney will use various strategies to challenge the credibility of the officer's observations, such as:

  • Reviewing the officer's past cases to check for patterns or inconsistencies in their reporting.

  • Highlighting potential biases or prejudices that could have influenced the officer's judgment.

  • Presenting expert witnesses who can testify about the reliability and accuracy of SFSTs.


Being charged with a DWI in Houston can be an overwhelming and frightening experience. However, with the right defense strategy, including effective cross-examination of the police officer on the standardized field sobriety tests, you stand a better chance of securing a favorable outcome. If you find yourself facing DWI charges, it is essential to seek the counsel of an experienced Houston DWI attorney who can skillfully challenge the evidence presented against you and protect your rights.

For litigants who do not have counsel: Reading this blog post does not create an attorney client relationship. Call to set up a free consultation.

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