Phoenix Arizona DUI Cases - Field Sobriety Tests

by Aaron M. Black • December 24, 2020

DUI Traffic StopTraffic officers in Arizona have an arsenal of ways to screen someone who is suspected of driving while impaired by alcohol or drugs. These initial screenings are based in law, training and physiology.

The first event in a DUI arrest is an officer who witnesses a traffic infraction such as a burned out brake light or straddling a double yellow lane line. The officer then has a sufficient legal reason to make a traffic stop. And after asking questions if impairment is suspected, the officer will invite the suspect to take a field sobriety test.

Refusing to participate in the field sobriety screening, which is your legal right, can result in a one-year suspension of your driver’s license, if it is your first offense. If it is your second offense, your license can be suspended for two years.

DUI pre-arrest Field SobrietyTests

If you are stopped for suspicion of impaired driving, there are several Field Sobriety Tests that you likely will be facing. The officer will give you specific oral instructions to follow during these tests. ALWAYS politely refuse to conduct the pre arrest field sobriety tests.

Walk and turn: First is the walking test, usually nine heel-to-toe steps forward and nine backward on a straight line counting the steps out loud while watching your feet and turning using short steps to finish the turn. This tests muscle control and short term memory by recalling the instructions.

In this test the officer observes certain clues. If you cannot balance during the instructions; you start to walk too soon; you stop while walking; not touching heel-to-toe; stepping offline; using your arms to balance; unable to balance on turns; as well as you take more or fewer steps than instructed.

If the suspect steps off the line, almost falls, or cannot finish the test, he or she fails the test.

One leg stand: The suspect with feet together stands and raises one leg about six inches off the pavement and looking at the raised foot with arms at the sides while listening to instructions. This test has two criteria: following instructions, balancing and counting out loud until told to stop.

The suspect needs to stand on one leg for 30 seconds while impaired people can reach 25 seconds but no more.

The officer will watch to see if the suspect sways, hops, uses arms for balance or puts the raised leg down. People who do these things indicate that the BAC is higher than the legal limit of 0.08 percent.

Horizontal Gaze Nystagmus- HGN - DUI Sobriety Field Test

“Horizontal Gaze Nystagmus” (HGN): Nystagmus means involuntary jerking of the eyes. The officer moves a pen back and forth a few inches in front of the suspect to follow the movement of the eyes. The officer observes if any involuntary eye movements happens. If based on these screenings the officer concludes the suspect is impaired, which is an evidence-based opinion, the officer then decides if there is sufficient probable cause to take the next steps in developing incriminating evidence.

Therefore, failing or performing poorly in the pre-screening phase allows the officer to test the suspect’s breath using a breathalyzer and in some cases a blood test thereby introducing science into the case to determine the blood-alcohol concentration.

Drug recognition experts

Arizona has a program to train law enforcement officers in recognizing the several signs of impairment by drugs and to accurately identify the category of the drugs involved.

These officers are termed Drug Recognition Experts (DRE) and to earn that rating they must finish a three phase program lasting 88 hours. They must be recertified every two years.

Although Phoenix has certified only 26 DRE officers, they can be summoned to the scene of a traffic stop by an officer who has not undergone the training.

Reliability issues of pre-arrest Field Sobriety Tests

The officer does not have any knowledge of the suspect’s physical or mental abilities when conducting a field sobriety screening, so a poor performance can persuade the officer to move into the accusation phase and handcuffs.

For example, the officer would not necessarily know that a suspect cannot balance standing on one leg because of a physical ailment or injury, and balancing in any situation is problematic because of an inner ear condition. Nor would the officer know about back, leg, and foot injuries that are responsible for poor performance.

Failing the eye test can be the result of a neurological condition which the officer could not possibly know about. There are also over 40 different causes of nystagmus. HGN is only caused by alcohol. Can the officer differentiate HGN from any of the other 40 caused of nystagmus?

In addition, being stopped by police can cause some people to experience anxiety and performing several unfamiliar tests while in an anxious state can lead to failing one or more of the pre-arrest tests.

While, people with mental disabilities may not be able to fully understand the officer’s directions and that will lead to failing the screenings.

Also, the National Highway Traffic Safety Administration (NHTSA) standardized and validated the three tests above. That means that all the tests must be conducted in the same standardized manner. If they are not conducted the correct way, the test is not valid. In addition, these tests have not been validated for people over the age of 65 or more than 50 pounds over-weight.

Available DUI defenses

An arrest for impaired driving results from failing any of these screenings.

Common DUI defenses are available to those who are charged with a misdemeanor or felony DUI. Common DUI defenses in Arizona are:
  • Lack of probable cause or reasonable suspicion to make the traffic stop
  • Pre-arrest screening results were conflicted
  • Slight impairment did not exist
  • The Miranda right to remain silent was not given
  • Breathalyzer test result was not accurate
  • Blood taken was contaminated or not properly stored
The defense will conduct an independent investigation to develop evidence favorable to the defendant and scrutinize the state’s evidence including the arresting officer’s conduct at the traffic stop and the officer’s record.

A competent defense works to earn an acquittal or case dismissal and save the defendant from incarceration, however brief, significant fines and a criminal record that can harm the defendant’s reputation in the community.

Free, confidential case assessment

If you or a loved one is facing a DUI charge learn what your options are by arranging for my free and confidential case review without any obligation to use me for your defense. To make an appointment can my hot-line at any time, 480-729-1683 or use my quick contact form online. I will respond promptly unless I’m in court.

I have years of experience defending pre-arrest DUI screenings and a record of aggressively defending clients and challenging the state’s evidence while providing personalized service. You’ll never be pushed off to an assistant. You’ll always be talking directly to me.

During the pandemic we can meet online at FaceTime and communicate by phone, text, and email and courts are holding virtual sessions.

I defend DUI and pre-arrest screenings in the justice, municipal, state, and federal courts in Maricopa and its surrounding counties.


About the Author

Aaron Black Phoenix DUI LawyerAaron Black is the founder and sole attorney of the Law Office of Aaron Black. Located in Phoenix, Arizona, his DUI and criminal defense law firm provides legal services to people who have received felony or misdemeanor charges from the state.

Aaron has developed a strong interest in defending people who have been arrested and received criminal charges for driving under the influence. With his professionalism and knowledge of Arizona DUI and criminal law, he has acted as a check and balance on the police, prosecution and courts and has protected a great number of his clients from excessive and unfair sentencing.

Along with DUI defense, Aaron handles a range of other criminal defense matters, including aggravated assault, burglary, domestic violence, drug possession, drug trafficking, fraud defense, insurance fraud, sex crimes, and white-collar crime cases.

After graduating college in 2003 from the University of Arizona, Aaron decided to pursue a law degree. He followed a family long tradition and went to the University of South Dakota School of Law where he pursued his goal of becoming a criminal defense lawyer.

After passing the Arizona and South Dakota bar exams, Aaron joined the Maricopa County Office of the Public Defender where he defended hundreds of people charged with serious criminal offenses. His work as a public defender helped him sharpen his litigation skills and gave him a unique insight into the Arizona criminal justice system.

Over the course of his 15-year legal career, Aaron has spent a considerable amount of time in both Arizona justice, municipal, state and federal courts. He has argued over 50 jury trials, tried over 100 bench trials and has become one of the highest-rated criminal and DUI defense attorneys in Phoenix and the surrounding areas. He has received a 10/10 rating from the legal directory Avvo because of his legal background and successful case record. Since 2014, he has received the Super Lawyer rating for his work as a Phoenix DUI Attorney and criminal defense attorney.

You can review Aaron’s Attorney Bio page for more information about his background, education and experience as a Phoenix DUI and criminal defense attorney.
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