In DWI stops, police in Texas use SFSTs, or Standardized Field Sobriety Tests, to determine if a person’s driving ability is impaired.

However, SFSTs are not always accurate. There are several reasons why a person may perform poorly, including anxiety, poor balance, poor roadside conditions, and incorrect procedure by the officer. 

Michael & Associates often uses mistakes and flaws in the SFST process to earn clients a dismissal or reduction. If you are facing DWI charges today, time is of the essence! The best thing you can do to protect your future and your liberties is to contact an experienced DWI attorney to discuss your circumstances. Book your free case review with Michael & Associates now.

What is SFST in Texas?

Standardized Field Sobriety Tests were developed and validated by the National Highway Traffic Safety Administration (NHTSA) in the 1970s. They consist of a series of tasks that law enforcement officers conduct in a standardized manner, with specific instructions and evaluation criteria, to assess whether a driver is impaired due to alcohol or drug consumption.

The tasks are considered “divided attention tests,” designed to assess an individual’s ability to perform the mental and physical multitasking needed for safe driving.

Police officers will usually ask a motorist to perform SFSTs after making a traffic stop and talking, but before making an arrest.

If an officer asks the driver to perform SFSTs, there’s a good chance they already suspect impairment. Poor performance of the tests gives officers probable cause for arrest, and the results can be used as evidence of DWI in court.

SFSTs are widely used in DWI arrests, but that doesn’t mean they are always accurate or that the evidence gathered from the tests can’t be challenged. Since it’s up to the arresting police officer to judge how well someone performs in field sobriety tests, the results are subjective. Furthermore, many factors can affect a person’s performance in SFSTs, especially in the case of hidden disabilities and less-than-ideal roadside conditions.

Understanding how each of the tests works reveals the problems that come with standardized field sobriety tests.

Horizontal Gaze Nystagmus test (HGN)

Nystagmus is an involuntary jerking of the eyes that happens when an intoxicated person gazes to one side. HGN tests are considered very accurate in determining whether a person is drunk, but the test must be performed correctly.

When conducting a horizontal gaze nystagmus test, the officer must first check for equal pupil sizes, resting nystagmus (which can indicate health issues or drug use), and whether the eyes can track an object together (equal tracking). Unequal pupil sizes and unsynchronized tracking can be signs of medical disorders or injuries.

The officer should then give clear verbal instructions before beginning the test. They will hold an object, such as a pen, 12–15 inches away from the subject’s nose and slowly move it side to side in a horizontal line. The subject is expected to follow the object with their gaze while the officer looks out for one of three “clues” that point to intoxication:

• The lack of smooth pursuit, where the eyes jerk or bounce as they follow the object, like “windshield wipers moving across a dry windshield.”
• Distinct and sustained nystagmus when the eye is held as far to the right or left as possible for a minimum of four seconds.
• Onset of nystagmus prior to 45 degrees. If the eye begins jerking before the object reaches 45 degrees to the left or right.

Walk and Turn test (WAT)

The walk and turn test consists of taking nine heel-to-toe steps along a straight line before turning in a specific manner and walking back. This is a divided attention test designed to measure the subject’s ability to follow instructions in a series of steps while their attention is divided over physical and mental tasks.

Before testing, the officer should consider their environment, including the surface (where possible, it should be reasonably dry, hard, level, and non-slippery), the subject’s age, weight, and any injuries or disabilities.

The WAT test is made up of two parts:

• Instruction stage: the subject must maintain a heel-to-toe position on the line while the officer explains the instructions. An inability to multi-task (listen to instructions and maintain balance) is considered a “clue” pointing to intoxication.
• Walking stage: The subject must take nine heel-to-toe steps with their arms kept by their side and count each step aloud. Balancing difficulty, pausing, failing to follow instructions, taking the wrong number of steps, and failing to walk heel-to-toe can all be deemed signs of intoxication.

During the WAT test, officers look out for the following eight clues:

• Inability to maintain balance during the instruction phase
• Starting too soon
• Stops walking
• Misses heel-to-toe
• Steps off the line
• Uses their arms for balance
• Improper turn
• Incorrect number of points

One Leg Stand test (OLS)

The one-leg stand requires balancing on one foot while keeping the other foot a few inches off the ground for around 30 seconds. As with the WAT test, this is a divided attention test designed to assess the subject’s ability to multitask.

Before beginning the test, the officer should assess the subject for physical problems or disabilities.

The OLS test consists of two parts:

• Instruction stage: The subject is asked to stand with their feet together and arms at their side. They must maintain this position as the officer provides instructions for the next stage of the test.
• Balancing stage: The subject has to raise one leg, approximately 6 inches off the ground, and count out loud until told to stop.

During the OLS test, the officer will look out for the following four clues:

• Swaying while trying to balance
• Using arms to balance
• Hopping
• Putting foot down

How Accurate Is the SFST?

According to the NHTSA, when all three standardized field sobriety tests are combined, they are 91% reliable in determining if someone is intoxicated. Furthermore, they claim:

• The HGN test is 88% accurate
• The WAT test is 79% accurate
• The OLS test is 83% accurate

These numbers are based on the San Diego SFST validation field study from 1998, but the same study shows that false positives do happen.

The following factors can affect a person’s performance results in the tests and lead to false positives:

• The officer’s training and experience: Untrained and inexperienced officers can judge incorrectly.
• Medical conditions: Certain medical conditions and physical disabilities can give false results.
• Age/weight/injury: Physical factors, such as a person’s weight, mature age, and injuries, can contribute towards poor performance of the tests.
• Environmental factors: Many environmental factors can affect a person’s performance, including a rough or uneven surface, windy or rainy conditions, dark lighting or glare from the sun, and a noisy background.
• Language barriers: The tests can only be performed properly if the subjects clearly understand what is expected of them.

How Challenging Is It to Successfully Complete the SFST?

SFSTs can be challenging to pass, even if you are sober. Most people will already be in a state of anxiety when pulled over by officers. They are then expected to listen to and carry out a series of tests by performing tasks they probably haven’t practiced since childhood.

Balancing on one leg or standing heel-to-toe is not an everyday action for most people. When put on the spot, it can be a challenging task to pull off without swaying. The task becomes even more difficult when considering additional factors, such as being overweight, having joint pain in your knees or hips, or even old age.

If that’s not enough, there are also environmental factors to contend with, such as wind, fast cars passing by, or uneven ground—all of which can make the tests even harder to pass.

When it comes to listening to and following a series of instructions, people with additional learning needs—such as ADHD—may find themselves making mistakes even when entirely sober.

Does Failing SFSTs Indicate Intoxication?

Failing SFSTs does not always indicate intoxication. There are various reasons why someone might fail one or more SFSTs, including an incorrect judgment by the officer, medical conditions, prescription medication, and environmental factors.   

How Do Field SFST Results Impact a DWI Court Decision in Texas?

If you fail SFSTs in a DWI stop, this will likely be used as evidence against you in court. Officers will probably have dashcam footage of you conducting the tests, accompanied by a testimony that the tests were administered correctly and according to NHTSA standards.

If evidence shows that the tests were not administered properly, the results will not be admissible in court. Either way, a criminal defense lawyer can still dispute the validity of the results since field sobriety tests are highly subjective, unlike blood results.

Is Certification Required for Officers Conducting SFST in Texas?

Yes. Police officers receive SFST certification during their time at police academy after completing a 24-hour course. During the 3-day course, officers are taught about the history, administration, standardized testing, and scoring of field sobriety tests, including correct and proper procedure.

Does Your Attorney Need SFST Certification in Texas?

Your attorney doesn’t need SFST certification to be able to defend you. However, being well versed in correct procedure according to NHTSA means that they will be able to swiftly spot any inconsistencies or flaws that may have taken place during your field sobriety tests and then use this to challenge your DWI case in court.

Whether they have SFST certification or not, finding a skilled defense attorney with experience and a track record of success in DWI cases is essential.

The Best Defense Tactics After Failing the SFST in Texas

If you fail SFSTs in Texas, you’ll probably be placed under arrest and taken to jail. The evidence from your tests should be available for review by both prosecutors and your defense attorney.

It is imperative that you find a skilled criminal defense attorney with experience in DWI cases. They will study the evidence, including any video footage of your field sobriety tests, to look for inconsistencies, faults, or improper procedures by the police officer. If the test was not conducted according to NHTSA standards, the results cannot be used against you in court.

Aside from thousands of dollars in fines, a criminal record, and jail time, a DWI conviction can irrevocably damage your life through a host of collateral consequences. It’s downright frightening, but you don’t have to face your DWI case on your own. Contact Michael & Associates to get a free case review today.