If you’ve been arrested for DUI, you’ve likely encountered Field Sobriety Exercises or Standardized Field Sobriety Tests (SFSTs). These tests, designed to assess impairment, are often presented as irrefutable evidence. However, they are far from perfect and can be vigorously challenged by a skilled DUI defense attorney. We understand the complexities of SFSTs and how to use their inherent flaws to protect your rights.

What Are Standardized Field Sobriety Tests (SFSTs)?
Law enforcement uses three primary SFSTs to evaluate a driver’s potential impairment:
- Horizontal Gaze Nystagmus (HGN): This test checks for involuntary eye movements (nystagmus) that may indicate alcohol or drug use. While presented as scientific, it is highly subjective and prone to error.
- Walk-and-Turn (WAT): This test assesses your balance, coordination, and ability to follow instructions. It requires you to take nine heel-to-toe steps, turn, and return.
- One-Leg Stand (OLS): This test measures your balance and ability to maintain focus while standing on one leg for 30 seconds.
Video of Field Sobriety DUI Investigation
The Flaws and Limitations of Field Sobriety SFSTs:
While these tests are presented as ‘standardized,’ their reliability is often questionable. Here’s why:
- Subjectivity: The officer’s interpretation of your performance is subjective, leading to potential bias.
- Environmental Factors: Uneven surfaces, poor lighting, and weather conditions can significantly impact your balance and coordination.
- Medical Conditions: Inner ear issues, neurological disorders, physical disabilities, and age-related balance problems can mimic impairment.
- Nervousness and Anxiety: The stress of a DUI stop can significantly affect your performance.
- Officer Error: Even minor deviations from the NHTSA’s strict standardized procedures can invalidate the test results.

Beat Your DUI: 5 FAQs on Challenging SFST Results
Your attorney will meticulously reconstruct the testing scenario by gathering detailed accounts of the environmental conditions (e.g., uneven ground, poor lighting, traffic noise), the timing of the tests, and your physical/emotional state. These factors can significantly impact SFST performance. By identifying discrepancies between the officer’s report and the actual conditions, your attorney can argue that the results are unreliable.
Yes. Your attorney will delve into the scientific foundations and limitations of SFSTs, as outlined in the NHTSA guide. They will emphasize that factors like medical conditions, fatigue, and natural coordination can lead to false positives. They may also introduce expert testimony to explain how these factors can affect the tests, undermining the prosecution’s reliance on SFSTs as conclusive evidence of impairment.
Your attorney will meticulously examine the officer’s training records to ensure they were adequately trained according to NHTSA standards. If the officer’s training is deficient or they failed to adhere to the guide’s recommendations, your attorney can argue that they lacked the expertise to administer the tests accurately. This can lead to the suppression of SFST results.
Your attorney will scrutinize the officer’s documentation and testimony for consistency with the NHTSA guide’s prescribed scoring criteria and legal requirements. Any discrepancies, gaps, or subjective interpretations can be used to cast doubt on the reliability of the officer’s assessment and potentially exclude the evidence.
The NHTSA manual is the standard for how these tests are to be conducted. Your attorney will use the manual to verify that every step of the tests was conducted properly. If there is a deviation from the manual, even a small one, that can be used to call the validity of the tests into question. Also, the manual itself lists many reasons that these tests can return false positives, and your attorney will bring those to the attention of the court.
How a Skilled DUI Attorney Can Challenge SFSTs:
As a competent DUI defense attorney, I meticulously examine every aspect of the SFSTs to identify potential flaws and inconsistencies. Here’s how:
Reconstructing the Scene:
I gather detailed accounts of the conditions of the testing, and compare them to the requirements of the NHTSA manual.
Scrutinizing Officer Training and Adherence:
I verify the officer’s training records to ensure they are certified and up-to-date with NHTSA standards.
I analyze video footage and the officer’s report to identify any deviations from standardized procedures. The NHTSA manual is very specific, and slight deviations can be used to question the results.
Challenging the Scientific Validity:
I highlight the inherent limitations of SFSTs and their susceptibility to false positives.
I can introduce expert testimony to explain how various factors can influence test results, including medical conditions and environmental factors.
Leveraging Documentation and Testimony Discrepancies:
I thoroughly compare the officer’s written report, video footage, and courtroom testimony to identify inconsistencies.
I also scrutinize the officers other observations, outside of the SFST’s, such as speech, and other observations.
The Police Use This Book to Convict You:
Your Rights and What to Do:
If you’re stopped for DUI, remember these critical points:
- You have the right to remain silent. Do not volunteer information beyond what is required.
- You have the right to an attorney. Exercise this right immediately.
- Document everything you remember about the SFSTs, including the officer’s instructions, testing conditions, and your physical and emotional state.
Don’t let flawed SFSTs determine your future. Contact DUI2Go today for a free consultation. We will aggressively defend your rights and challenge the evidence against you.”
Call to Action:
Call us now at 813-222-2220 or fill out our online contact form for a free, confidential consultation.”
More Detailed Review of DWI Detection and Standardized Field Sobriety Testing (SFST) Training
More Links to Our Field Sobriety Information
Our extensive analysis of standardized field sobriety testing training materials equips us to dissect every step of your arrest, revealing deviations from protocol that create powerful defenses against DUI charges.
Challenging Field Sobriety Exercises in DUI Cases
Law enforcement, charged with maintaining the safety of our streets, rely on their common sense and observations when determining whether probable cause exists to arrest an impaired driver. However, there are limits to those observations when those same officers must testify in a criminal trial when a Defendant’s liberty is at stake. Permitting law enforcement to give an opinion or inference about whether a particular Defendant is impaired is inappropriate absent proper foundation.
In the last few years, Florida’s evidentiary framework has fundamentally changed, and there are more stringent requirements on the admissibility of opinion testimony. If the State of Florida wants to elicit testimony that the Defendant was impaired, the State must satisfy Daubert.
Scientific Basis Continued: NHTSA Guidelines and Empirical Testing
The scientific underpinning of FSEs is emphasized by NHTSA’s continuous efforts to update its training materials based on advances in research, technology, and science. These exercises are not mere subjective observations; they are designed to adhere to the scientific method, involving empirical testing, blind experiments, and adherence to established principles.
The NHTSA manuals, particularly the most recent one from May 2013, explicitly state that these materials are a “living document” subject to updates based on scientific advancements. Each FSE described in the manual includes references to empirical testing, highlighting the commitment to scientific rigor in their development and maintenance.
The State’s Legal Obligation
Florida courts, following the amendment of Florida Statute § 90.702, place the burden on the proponent of evidence to establish admissibility by a preponderance of the evidence. This principle aligns with federal courts of appeal, where Daubert has been the standard for years.
It’s crucial to recognize that the burden of proof on the State does not change with the adoption of Daubert. The State must still demonstrate the reliability of FSEs, providing evidence that these exercises meet the three criteria specified in Florida Statute § 90.702: sufficient data, reliance on scientific principles, and reliable application to the case at hand.
Legal Standards for Admissibility in Florida Courts
Post the amendment of Florida Statute § 90.702, Florida courts have explicitly placed the burden on the proponent of evidence to establish admissibility by a preponderance of the evidence. This fundamental principle is in harmony with the practices in federal courts of appeal, where the Daubert standard has long been the norm.
The revised statute reads as follows:
Testimony by experts.—If scientific, technical, or other specialized knowledge will assist the trier of fact in understanding the evidence or in determining a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education may testify about it in the form of an opinion or otherwise, if:
- The testimony is based upon sufficient facts or data;
- The testimony is the product of reliable principles and methods; and
- The witness has applied the principles and methods reliably to the facts of the case.
This legal framework underscores the significance of ensuring that any expert testimony, including that related to Field Sobriety Exercises (FSEs), meets the rigorous standards of reliability and relevance mandated by the Daubert standard.
Proponent’s Burden and Daubert Standard
The burden placed on the proponent of evidence to establish admissibility aligns with the long-established practices in federal courts, where the Daubert standard has been the touchstone for assessing the reliability and relevance of expert testimony. The Daubert standard emphasizes a thorough evaluation of the scientific methodology and principles underlying expert opinions, ensuring that they are not only based on sufficient facts but also derived from reliable and accepted principles and methods.
Florida’s commitment to this elevated standard, as reflected in the statutory amendment, places a crucial responsibility on the proponent to demonstrate the scientific validity and reliability of expert opinions, especially in cases involving complex scientific or technical knowledge, such as the interpretation of Field Sobriety Exercises in DUI investigations.
Challenges to Reliability: Inaccuracies and Error Rates
The accuracy rates disclosed by NHTSA for individual FSEs reveal potential inaccuracies and error rates that cannot be ignored. The walk and turn, one-legged stand, and horizontal gaze nystagmus tests, even when administered correctly, come with inherent risks of falsely accusing individuals of impairment.
Moreover, the absence of certain tests from NHTSA’s approved list raises questions about the overall reliability of FSEs. When a scientific basis is lacking for specific exercises, it calls into question the validity of the entire test battery. The court, acting as a gatekeeper under Daubert, has a duty to assess the reliability of the evidence before it is presented to the jury.
Detailed Challenges to Use of Field Sobriety Exercises
The scientific foundation of Field Sobriety Exercises (FSEs) is under scrutiny, primarily due to the revealed inaccuracies and inherent error rates acknowledged by the National Highway Traffic Safety Administration (NHTSA). While these exercises are designed to assist law enforcement in identifying impaired drivers, their reliability is far from infallible.
The three commonly employed FSEs, namely the walk and turn, one-legged stand, and horizontal gaze nystagmus tests, are not immune to errors, even when administered correctly. The accuracy rates, as disclosed by NHTSA, expose potential risks of falsely accusing individuals of impairment based on these exercises.
1. Walk and Turn: NHTSA’s own materials acknowledge that the walk and turn test, when conducted properly, boasts an accuracy rate of, at best, 79%. This means that in more than 20% of cases where the test is administered correctly, there is a risk of misjudging an individual as impaired.
2. One-Legged Stand: Similarly, the one-legged stand test, considered reliable by NHTSA under optimal conditions, reveals an 83% accuracy rate. This implies that in nearly 17% of cases, individuals may be incorrectly identified as impaired based on this test alone.
3. Horizontal Gaze Nystagmus (HGN): The HGN test, often touted for its effectiveness, presents an accuracy rate of 88% when administered correctly. While this seems relatively high, it still means that approximately 12% of individuals may be erroneously identified as impaired due to the test’s limitations.
These error rates are not negligible and raise serious concerns about the reliability of FSEs in determining impairment. It’s essential to underscore that even when law enforcement follows the prescribed procedures, the risk of misjudgment persists.
Moreover, the absence of certain tests from NHTSA’s approved list introduces an additional layer of doubt regarding the overall reliability of FSEs. The scientific basis for specific exercises might be lacking or insufficiently demonstrated, prompting questions about the validity of the entire battery of tests.
As the court acts as a gatekeeper under the Daubert standard, it assumes the responsibility of critically evaluating the reliability of the evidence before allowing it to be presented to the jury. The potential for inaccuracies and error rates in FSEs should be carefully considered, and the court must weigh these factors when determining the admissibility of such evidence.
Conclusion: Admissibility Hinges on Scientific Validity
Field Sobriety Exercises are a critical component of DUI investigations, but their admissibility in court hinges on their scientific validity. The State of Florida, as the proponent of this evidence, must meet the burden of proving the reliability of FSEs under the Daubert standard.
NHTSA’s acknowledgment of FSEs as a scientific tool, subject to updates based on research and technology, underscores their significance. However, it also places a responsibility on the State to establish that these exercises meet the criteria set forth by Daubert.
One may argue that FSEs are inadmissible unless the State can demonstrate their reliability through a Daubert hearing. As the legal landscape evolves, it becomes imperative to uphold rigorous standards for the admission of evidence, ensuring that only scientifically valid and reliable information reaches the jury.
Summary of the “Science” of Field Socriety Exercises
In recent years, changes to Florida’s evidentiary framework demand stricter requirements for the admissibility of opinion testimony in DUI cases. The State must now satisfy the Daubert standard to present evidence of a Defendant’s impairment. Scientific underpinnings of Field Sobriety Exercises (FSEs), continuously updated by NHTSA, emphasize empirical testing and adherence to scientific methods.
Florida courts, aligning with federal standards, place the burden on the State to establish admissibility post-amendment of Florida Statute § 90.702. The Daubert standard demands a thorough evaluation of FSEs, necessitating sufficient data, reliance on scientific principles, and reliable application.
Challenges arise in the form of disclosed inaccuracies and error rates in individual FSEs, prompting questions about their overall reliability. Walk and turn, one-legged stand, and horizontal gaze nystagmus tests, despite touted effectiveness, exhibit significant error rates. Courts, acting as gatekeepers under Daubert, must assess evidence reliability before jury presentation.
In conclusion, the admissibility of FSEs hinges on scientific validity. Florida’s legal landscape now requires the State to meet the Daubert standard rigorously, ensuring only scientifically valid and reliable evidence reaches the jury in DUI cases.
Protect Your Rights
If you or someone you know is facing DUI charges based on Field Sobriety Exercises, it’s crucial to seek legal counsel immediately. Call the experienced DUI defense lawyer at 813-222-2220 for assistance. Safeguard your rights and challenge the admissibility of evidence in your case.







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