When a driver is pulled over for suspicion of driving under the influence (DUI), the highway patrol officer will usually try to use field sobriety tests (FSTs) and/or a breathalyzer test to prove that the driver is intoxicated. If this happened to you, it’s likely that the officer told you that the test results are irrefutable and “very scientific.” What they don’t want you to know is that breathalyzers and field sobriety tests can be inaccurate and therefore challenged, especially by an experienced DUI defense attorney.
How Do Field Sobriety Tests Work?
Field sobriety tests are a series of physical and cognitive exercises administered by police officers during traffic stops to assess a driver's level of impairment. The tests work by requiring the driver to complete a test as cleanly or accurately as possible while the police officer judges their actions and behaviors. By their nature, field sobriety tests rely on the officer’s subjective opinion, not objective fact. Furthermore, the primary purpose of a field sobriety test is not to determine the driver’s sobriety but rather to provide officers with enough evidence to justify an arrest for suspected DUI.
Three common types of field sobriety tests are:
- Walk-and-turn test: The walk-and-turn test involves the driver walking heel-to-toe along a straight line, turning on one foot, and walking back the same way. Officers look for balance, the ability to follow specific instructions, and any signs of stumbling or stepping off the line.
- One-leg stand test: The driver is instructed to stand on one leg while counting aloud until told to stop. This test assesses balance and the ability to perform simple tasks while divided attention is required. Officers watch for swaying, using arms for balance, or putting the lifted foot down.
- Horizontal gaze nystagmus test: Also called the pen test, in the horizontal gaze nystagmus test, the officer asks the driver to follow a moving pen with their eyes. The officer observes the eyes for involuntary jerking movements, which can indicate impairment.
How Do Breathalyzers Work?
Breathalyzers function by estimating a person's blood alcohol content (BAC) through the analysis of their breath. When a driver suspected of DUI blows into a breathalyzer, the device uses a chemical reaction to measure the amount of ethanol vapor in the breath. This reaction typically involves a fuel cell or infrared spectrometry to generate an electrical current or light absorption reading, which is then converted into a BAC estimate.
Highway patrol officers often use handheld breathalyzer devices during traffic stops. A handheld device is generally less accurate than larger, more sophisticated breathalyzers that are kept in police stations or jailhouses where arrested drivers are processed and eventually charged with DUI if the evidence justifies it.
Questioning the Validity of Field Sobriety Tests
If you are arrested for a DUI, you should hire a local DUI defense attorney who can question the validity of a field sobriety test, scrutinize how the test was administered, and emphasize the subjective nature of the results. Your attorney may argue that the officer did not follow standardized procedures, which can lead to inaccuracies. They can also highlight inconsistencies in the officer's observations or challenge the conditions under which the test was conducted, such as poor lighting or uneven surfaces. By questioning these aspects, it can cast doubt on the reliability of the test as evidence of impairment.
Different factors that could make a field sobriety test inaccurate include:
- Medical conditions: Certain medical conditions, such as inner ear disorders, neurological issues, or physical disabilities, can affect balance and coordination, leading to poor performance during field sobriety tests.
- Environmental influences: Factors like uneven pavement, poor weather conditions, or inadequate lighting can impair a driver’s ability to perform FSTs.
- Footwear and clothing: Certain footwear, such as high heels or loose-fitting shoes, along with restrictive clothing, can hinder a person's ability to perform physical tasks during the tests.
- Nervousness or anxiety: The stress of being pulled over and tested by law enforcement can affect a driver's performance by causing them to experience high anxiety.
Challenging the Science of Breathalyzer Tests
Your DUI defense attorney might be able to challenge the results of a breathalyzer test by highlighting potential sources of error that could compromise the accuracy of the readings. Breathalyzer devices require regular calibration and maintenance to produce accurate measurements; any lapses in these procedures can lead to incorrect results that report a BAC that is much higher than the driver’s actual BAC. Also, improperly administrating a breathalyzer test by an officer with not enough training on how to use it can introduce all sorts of unpredictable errors.
Furthermore, physiological factors, such as medical conditions or recent ingestion of certain substances, can skew results. It is also believed that an upset stomach that causes indigestion could trigger an inaccurate BAC reading.
By focusing on these potential inaccuracies, your attorney could dispute the reliability of the breathalyzer results in court. It might be possible to have the results deemed inadmissible, which would likely be devastating to the state’s case against you.
When the Evidence is Against You, Hire a Lawyer
If the prosecution intends to use field sobriety test results or breathalyzer results as part of its case to potentially put you behind bars after a DUI arrest, you should start your defense with a professional’s representation and guidance. DUI laws are complex, and you will need in-depth knowledge to effectively challenge the accuracy and reliability of the test results. With an attorney leading the way, though, you can depend on their experience and knowledge instead.
At MayesTelles PLLC in Phoenix, Arizona, we proudly offer our defense counsel to locals who were arrested for DUIs. We know that the stakes in a DUI case are high, with potential consequences including hefty fines, license suspension, and even incarceration. Discover how to defend yourself against the conclusion of a field sobriety or breathalyzer test by working with our team today.
Get a free case consultation. Dial (602) 428-7104 now.