When it comes to field sobriety test accuracy, quite a few concerns have been raised within the legal community. And if you’ve recently been pulled over for DWI, however you’re likely wondering things like: Can these tests really be taken all that seriously? Can they successfully be used against me in court? Just how accurate is a field sobriety test? 

To be blunt, the average field sobriety test is designed for failure. The test is extremely flawed, highly subjective, and very difficult to pass — even if you are sober. The point is that there are many outlying factors that can impact the how you perform on field sobriety tests, and alcohol is only one of those factors. 

To bring this home, let’s break down the main 3 parts of the Texas field sobriety test.

What are the 3 field sobriety tests?

The three sanctioned field sobriety tests (FSTs) that comprise the overarching field sobriety test are:

  • The one-leg stand test
  • The walk-and-turn
  • The horizontal gaze nystagmus test 

Each of these tests is meant to measure how you respond to certain tasks that are hard to perform well if you’re drunk. Of course, these tests are also hard to do if you’re sober. Failure of the test is considered probable cause for DWI arrest

Keep in mind that what we’re about to cover does not include non-sanctioned tests such as being able to recite the alphabet backwards. (If a police officer asks you to do this, they don’t expect you to actually be able to do it correctly; they’re hoping you’ll say something like “I can’t even do that sober.”)  

For more information on issues related to probable cause, check out our articles on Why Do Not Blow is Bad Advice and what to do if you suspect you were DWI with a .15 Blood Alcohol Level (or higher).  

The one-leg stand

How the test works

You must stand on one leg for a period of around 30 seconds. You are expected to keep the leg you aren’t balancing on held up for the entire period, without swaying or resting.

One-leg stand field sobriety test accuracy issues

Balance can be problematic for even the most fit people out there, especially if you don’t practice balancing regularly. Go ahead and give it a try. Even if you didn’t fall out of the balance for a moment, were you able to stand completely still?  

Now imagine taking the test if you are overweight. Or if you have issues with your ankles, knees, or hips. Or if you are over aged 60 (as we age, balancing becomes harder). 

Now, imagine compounding any of those issues with environmental factors. Balancing in your bedroom with the lights on is one thing, but what if you’re on the side of the road, with cars whizzing past? What if the wind is up? What if it’s dark, and you have a hard time fixing your eyes on point to help you stay balanced?  

Any of these circumstances can make balancing on one leg for 30 seconds a little bit trickier. 

The walk-and-turn test 

How the test works

You must walk, heel-to-toe, in a straight line with your hands directly at your side. When you get to the end of the line, you must turn around and walk back to the beginning of the line. Officers are looking for swaying, stumbling, or any issues staying on the line.

Walk-and-turn field sobriety test accuracy issues

Walking heel-to-toe in a straight line with your hands at your side is just flat-out weird. There’s no sane reason for anyone to walk like this, and it’ll take some practice to get used to it. The fact is that the average person will probably lose their balance almost immediately as they try to position their feet in the correct way.

Can this initial loss of balance be taken as a sign of drunkenness? Yes, it most certainly can be. But who died and made police officers the psychoanalysts of walking? Just because your body goes from side-to-side as you try to figure out how to walk in a way you’ve never walked in before does not mean you’ve been drinking. It simply means you’re a human. 

Another issue to consider with following these very unusual requests is the possibility of learning disorders or attention deficit disorders (such as ADHD) affecting the outcome. What if a person struggles with understanding and following instructions on a regular basis and the police officer interprets this as a sign of intoxication?

Horizontal gaze nystagmus test 

How the test works

A police officer will shine a flashlight in your face and move an object side to side. You are expected to follow the object with your eyes. With this test, officers are looking for telltale signs of alcohol impairment within your eyes — specifically, “jerking” and smoothness. Do your eyes jerk or bounce, or do they smoothly follow the object from side to side? 

Horizontal gaze nystagmus field sobriety test accuracy issues

Outside of alcohol, there are many situations that can lead to jerking — so it’s unfortunate that this has become one of the go-to field sobriety tests. In fact, this test is only said to be around 77% accurate. This is because there are more than a few “neurological, medical and eye conditions that could cause the onset of nystagmus.” 

So while this test isn’t exactly difficult for you to perform (like the one-leg stand), the standards for passing could be impossible to reach — even if you are completely sober.

Unfortunately, due to the simplicity of this test, it’s also very easy for an officer to manipulate you into taking the test without actually telling you that they’re performing a field sobriety test. This being said, if a police officer abruptly shines a light in your face and asks you to follow an object, be aware that they’re doing this to “test” your sobriety.

What happens if you fail a field sobriety test?

Now to answer the big question: What happens if you fail a field sobriety test? Or, more accurately phrased — what happens when you fail a Texas field sobriety test?

The good thing about field sobriety tests is that their inaccuracies could potentially work in your favor. If you fail a field sobriety test, you will likely be arrested. However, a good lawyer will use the known field sobriety test accuracy issues as a defense tactic. 

Keep in mind, just because you agreed to take a test and subsequently failed it does not mean you’ve admitted guilt (or even that you’re guilty of DWI). 

Can you refuse a field sobriety test? Sure, you can. But refusal to take a test does not guarantee you won’t be charged with DWI and likewise, failing one does not equate to automatic guilt.

Need help fighting a DWI charge? Contact Thiessen Law Firm.

Because of field sobriety test accuracy issues, failing a field sobriety test is not the end of the world. In fact, if you have a decent lawyer at your side, a failed field sobriety test could mean absolutely nothing in court. Problems with field sobriety tests can work in your favor. 

Thiessen Law Firm’s Triple Board Certified Lawyer-Scientist Mark Thiessen has successfully achieved over 100 Not Guilty verdicts and thousands of dismissals for DWI cases, making Thiessen Law Firm the go-to law firm for DWI in Houston.

If you’d like to learn more about how to fight back against a failed field sobriety test that resulted in a DWI charge, call us at 713-864-9000 or contact our team online today.

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Thiessen Law Firm

Mark Thiessen is an aggressive trial lawyer best known for his devotion to justice for his clients and high rank as a DWI Super Lawyer in Texas.