Have you been pulled over and requested to perform field sobriety tests? Many citizens can agree on how stressful and intimidating that very moment can feel. We understand that maybe you were tired, anxious, nervous, disconcerted, or simply just caught off guard—but the officer took your performance as a sign of “impairment.”  

But what if we told you that these tests are neither completely accurate nor a scientifically proven method? They depend on officers’ judgement, medical conditions, uneven surfaces, nerves, or poor lighting—factors that do not relate to alcohol or drugs but used to develop probable cause for arrest and used as evidence in court.

Due to their subjective nature and the potential for human error, the correct defense can make a crucial difference on the result of your conviction.   

The Three Most Common (Standard) Field Sobriety Tests (SFSTs)  

The National Highway Traffic Safety Administration (NHTSA) has approved three types of SFSTs for law enforcement officers to determine if a driver is impaired due to alcohol or drug influence based on his/her performance. Here’s what each involves, clues for impairment, and  why results can be misleading.  

Horizontal Gaze Nystagmus (HGN) Test  

The officer asks you to follow an object, such as a pen or flashlight, with your eyes while keeping your head still. They will look for involuntary jerking of the eyes, referred to as nystagmus, occurring as eyes gaze side to side. This is considered the “most accurate” test in the SFSTs.  

What officers look for – 4 or more clues “probably” mean BAC is at or above 0.08  

• Inability to smoothly pursuit the moving object (eyes can be observed to jerk or “bounce”)  

• Jerking of the eyes before the object reaches a 45-degree angle  

• Distinct jerking when eyes are held at maximum deviation for a minimum of 4 seconds.  

Why can it be unreliable:  

Many medical conditions, such as brain tumors and inner ear diseases, head injury, neurological disorder, prosthetic eye; if the person wears contacts especially colored contacts, officers’ failure to move the object smoothly, can cause similar eye movements or affect how your eyes respond.   

Walk-and-Turn Test (WAT)   

You’re asked to walk nine heel-to-toe steps in a straight line, turn on one foot, and walk nine heel-to-toe steps down the line—all while counting out loud, keeping your arms at your sides, and watching your feet at all times.  

What officers look for - Two or more clues “probably” mean BAC is at or above 0.08  

• Failure to keep balance while listening to the instructions.  

• Starting before the officer indicates that subject may begin the test.  

• Failure to maintain the heel-to-toe position throughout the instructions (subject leaves a space of one-half inch or more between the heel and toe).  

• Steps off the line.   

• Stops while walking.   

• Raising one or both arms six or more inches from the sides to maintain balance.  

• Improper turn  

• Taking more or fewer than 9 steps in either direction.  

Why can it be unreliable:   
Uneven surface, slippery surface, insufficient room; back, leg, or inner ear problems; individuals over 65 years of age; individuals wearing heels more than 2 inches; uncomfortable shoes, unusual footwear (i.e., flip flops, platform shoes, etc.); officer’s failure to provide correct and clear instructions  for the WAT, can easily affect balance, coordination and performance.

Even completely sober individuals often make “mistakes” that get interpreted as signs of impairment.  

One-Leg Stand Test  

You’re asked to raise one leg with the foot approximately 6 inches off the ground, keeping you foot parallel to the ground, holding that position and counting out loud in the following manner: “one thousand one, one thousand two…”) and so on until told to stop.   

What officers look for - Two or more clues “probably” means BAC is at or above 0.08  

• Swaying while balancing  

• Raising one or both arms six or more inches from the sides to maintain balance.  

• Resorts to hooping in order to maintain balance  

• Putting the foot down during the 30 second count  

Why it can be unreliable:  
Balance can be affected by uneven surface, non-slippery surface; individuals over 65 years of age; people with back, leg or inner ear problems; people who are overweight by 50 or more pounds; unusual footwear (i.e., flip flops, platform shoes, etc.);  if test lasts over 30 seconds; and individuals wearing heels more than 2 inches high, can make someone appear unsteady.   

The Reality: These Field Sobriety Tests Are Not Foolproof  

The results of field sobriety tests are highly subjective and officers use them to develop probable cause of arrest that they’ve already decided. The wrong assumption that every driver is physically capable to perform complex balance and coordination tests—a standard that simply is not true.   

That’s where we come in. Our skilled DUI lawyers will review the officer’s actions, due process, notable issues with the SFSTs, elaborate your mitigation, potential defense facts and challenge the credibility of the observations used against you.   

You Deserve a Fair Defense  

If you were arrested after a field sobriety test, you’re probably feeling frustrated, anxious, worried or frightened—but you are not alone. We’ve protected a lot of clients, their future, their license and their record, that went through your same exact situation.  

Before you make the decision that stands between you and your future by pleading guilty, talk to us. Our experienced DUI attorneys will know the best way to approach your case strategically to achieve the best possible outcome.  

Call us at (480) 648-3555 today for a FREE confidential consultation.  
You don’t have to face this alone—we’ll stand by your side every step of the way.  

Pre-Trial Defense: Lack of Probable Cause in DUI Cases  

When the Arrest Shouldn’t Have Occurred from the Beginning  

A lot of citizens do not take into account that being stopped or arrested for DUI doesn’t automatically mean the officers had a valid reason to do it.  

This is what we know as ‘probable cause’, one of the strongest defenses we raise before trial is that the officer did not evaluate each element of the crime to establish probable cause and make the arrest in the first place, therefore if you start subtracting elements, at what point does the officer no longer have probable cause?   

Under A.R.S § 13-3883, an officer may arrest a person if the officer has probable cause to believe a misdemeanor has been committed in the officer’s presence and probable cause to believe the person arrested has committed the offense.  Such belief must be entirely based on specific evidence, not just a hunch, feeling, or vague suspicion before placing you in handcuffs.  

If that probable cause is missing, your entire case can fall apart before it ever reaches trial since the State needs to prove that you were actually impaired.  

What Counts as Probable Cause in a DUI Arrest?  

An officer must point out the specific circumstances that would make any other officer, with the same kind of training and experience as the arresting officer, agree that a DUI likely occurred. Such circumstances may include:   

Police must be able to point to concrete observations that would make any other trained officer agree that a DUI likely occurred. These may include:  

• The smell of alcohol inside the motor vehicle or on the individual’s breath.  

• “Bad” driving indicators, such as swerving, swaying, speeding, or failing to use a turn signal.   

• Open containers inside the motor vehicle.   

• Slurred speech or mumbling.  

• Bloodshot, red or watery eyes.  

• Flushed, pale, perspiring or droopy face.  

• Poor performance on the SFSTs.  

• Unable to maintain balance.  

• Admission of drinking.  

• A positive preliminary breath test result (even though this result can’t be used at trial).  

Nevertheless, the arresting officer must establish probable cause throughout most of the above-mentioned signs. The officer must reasonably believe both that you were driving or in actual physical control of the vehicle and that you were impaired to the slightest degree.

If those elements aren’t supported by strong evidence, the arrest may have been unlawful.  

When Lack of Probable Cause Becomes Your Best Defense  

We often win probable cause challenges when:  

• There’s no proof of driving or control of the vehicle (for example, you were parked and asleep, or someone else had the keys).  

• There’s little or no evidence of impairment, such as when you performed well on field sobriety tests or no tests were conducted at all.  

• The officer arrested too early, before conducting a proper investigation or obtaining any real proof of intoxication.  

Remember: many DUI arrests happen before a blood alcohol test is even done. Officers often rely on quick assumptions — like red eyes or a faint odor of alcohol — to justify an arrest. But assumptions are not evidence, and courts know that.  

If we can show the judge that, based on the totality of the circumstances, there simply wasn’t enough to indicate actual impairment, your case could be dismissed before trial.  

Why You Need an Attorney Who Knows How to Challenge Probable Cause  

The lack of probable cause defense is highly technical and often decisive. It requires a deep understanding of police procedures, DUI law, and how judges interpret the “totality of the circumstances.”  

Our firm has successfully challenged arrests by exposing weak evidence, inconsistent officer testimony, and missing elements of the crime. We know how to dissect every step of the arrest — from the moment the officer activated their lights to the second you were handcuffed.  

If the officer didn’t have enough evidence to justify your arrest, you deserve to have that arrest thrown out — and we can help make that happen.  

Don’t Face a DUI Alone — Let’s Review Your Case  

If you believe you were stopped or arrested without solid evidence for field sobriety tests, reach out today.  
Every moment matters when your freedom, license, and record are on the line.  

Call us at (480) 648-3555 for a FREE confidential consultation — we’ll review your police report, video footage, and all available evidence to determine whether your arrest should be challenged.  

You have rights. We know how to protect them.