Getting pulled over for suspected DUI in Arizona is stressful and potentially life-changing. One moment you’re driving home, and the next, you’re being asked to step out of your car and submit to a DUI test. Many drivers don’t realize that a number of external factors can influence the results of field sobriety tests, breathalyzer readings, and blood alcohol concentration (BAC) levels — and not all of them are related to how much you’ve had to drink.
Understanding what can affect the outcome of a DUI test can play a major role in your defense. From medical conditions and medications to equipment errors and improper police procedures, these variables matter. If you’re facing a DUI charge, knowing what might have skewed your test results is critical.
Table of Contents
- What Are the Types of DUI Tests in Arizona?
- Medical Conditions That Can Affect DUI Test Results
- External and Environmental Influences on DUI Testing
- Medications and Substances That Can Skew BAC Levels
- Officer Error and Improper Test Administration
- Arizona’s Implied Consent Law and Your Rights
- Real-World Example of a Challenged DUI Test
- FAQs About Factors That Impact a DUI Test
- Important Things to Remember
- How a DUI Defense Attorney from Shah Law Firm Can Help
In this article, we break down the major factors that can impact DUI testing under Arizona law. We’ll explain your rights, what to watch out for during a traffic stop, and how experienced DUI defense attorney, Arja Shah, can help challenge the test results and protect your future.
What Are the Types of DUI Tests in Arizona?
Arizona law enforcement uses several methods to determine if someone is driving under the influence. The three most common include field sobriety tests, breathalyzer devices, and blood alcohol concentration (BAC) blood draws.
Under Arizona Revised Statutes § 28-1381, DUI charges can result if you’re:
- Impaired to the slightest degree
- Driving with a BAC of 0.08% or more
- Driving a commercial vehicle with a BAC of 0.04% or more
- Underage with any alcohol in your system (§ 4-244(34))
Each testing method has its own limitations and can be affected by factors unrelated to alcohol or drug use.
Medical Conditions That Can Affect DUI Test Results
Several medical conditions may falsely indicate impairment or skew test results. These include:
- Diabetes or Hypoglycemia: Can create ketones mistaken for alcohol in breath tests.
- GERD or Acid Reflux: Mouth alcohol can inflate BAC readings.
- Neurological Issues: Disorders like MS, vertigo, or brain injuries can affect balance during field tests.
- Fatigue or Stress: Mimics signs of intoxication such as slurred speech or unsteady gait.
An officer unaware of these conditions may misinterpret your behavior, resulting in an unfair DUI arrest.
External and Environmental Influences on DUI Testing
Environmental factors can interfere with roadside testing and skew the outcome of both sobriety and chemical tests.
Examples of external influences:
- Uneven or gravel surfaces affect balance during field tests.
- Bright flashing lights or low visibility can confuse a sober driver.
- Arizona heat can lead to dehydration, impacting blood alcohol distribution.
- Dust or strong wind might interfere with breathalyzer samples.
Conditions outside your control could make it seem like you’re impaired when you’re not.
Medications and Substances That Can Skew BAC Levels
Medications and even legal over-the-counter products can influence DUI test outcomes. Common examples include:
- Mouthwash or Breath Sprays
- Contain alcohol that may produce a false positive on breath tests.
- Cold Medicines (e.g., NyQuil)
- Contain sedating ingredients and alcohol.
- Prescription Drugs
- Oxycodone, Xanax, or sleep aids may cause impairment.
- THC/CBD Products
- Even trace THC can show up in blood tests.
Under ARS § 28-1381(A)(3), Arizona can charge you with DUI for being under the influence of legal drugs if they impair your ability to drive.
Officer Error and Improper Test Administration
Shortcomings in how police conduct DUI tests can cast doubt on your results.
- Uncalibrated Equipment: Breathalyzers require frequent calibration. Without it, results may be inaccurate.
- Mishandled Blood Samples: Improperly stored or labeled samples risk contamination.
- Timing Mistakes: Police must observe you for at least 15 minutes before using a breathalyzer to rule out mouth alcohol.
- Improper Field Sobriety Test Instructions: Officers must clearly explain the tests and ensure the environment is safe.
Any of these errors may be grounds for excluding test results in court.
Arizona’s Implied Consent Law and Your Rights
Under Arizona Revised Statutes § 28-1321, any person arrested for DUI is presumed to have given “implied consent” to chemical testing. However, there are key rights and penalties involved:
You have the right to:
- Refuse a preliminary breath test (PBT) before arrest.
- Speak with an attorney after arrest and before chemical testing.
- Request independent testing after the state-administered test.
Penalties for refusal:
- 12-month license suspension (first refusal)
- 24-month suspension (second refusal within 84 months)
- Possible requirement of an ignition interlock device upon reinstatement
Understanding these rules helps protect you from automatic penalties and further charges.
Real-World Example of a Challenged DUI Test
A 28-year-old nurse in Scottsdale was stopped for speeding and suspected of DUI. She admitted to taking a prescribed sleep aid the night before but had not consumed alcohol. She was still groggy and failed the walk-and-turn test.
The breathalyzer showed a BAC of 0.00%. However, the officer arrested her based on the failed field test and admitted use of a sedative. Her attorney, Arja Shah, obtained pharmacy records, expert testimony, and body cam footage showing poor lighting and gravel at the stop location.
The court dismissed the charges due to lack of impairment evidence and officer error during FST administration.
FAQs About Factors That Impact a DUI Test
⑴ Can you get a DUI from prescription drugs?
Yes, under ARS § 28-1381(A)(3), impairment from any drug can lead to a DUI, even if legally prescribed.
⑵ Do officers always have to calibrate breathalyzers?
Yes, and failure to do so could result in the breath test being thrown out in court.
⑶ What if I’m sick during the test?
A cold or flu can affect how you perform on FSTs, especially if you’re taking medicine with alcohol or sedatives.
⑷ Can I be forced to take a blood test?
Generally, not without a warrant. Police must show probable cause or obtain your consent, unless an emergency justifies the draw.
⑸ How can a lawyer challenge DUI test results?
Your lawyer can investigate medical conditions, test procedures, officer training, and lab handling to fight unreliable evidence.
Important Things to Remember
- Medical conditions like GERD, diabetes, or vertigo may distort DUI test results.
- External factors such as heat, lighting, or road conditions can affect field sobriety tests.
- Medications and mouthwash can result in false BAC readings.
- Officer errors in handling or administering tests are common and challengeable.
- Arizona’s implied consent law applies only after arrest — not before.
- You have rights. Knowing and asserting them early matters.
How a DUI Defense Attorney from Shah Law Firm Can Help
Attorney Arja Shah brings nearly 20 years of DUI defense experience and over 3,000 successful case outcomes to the table. She has helped countless individuals throughout Phoenix, Scottsdale, Mesa, and beyond challenge unreliable DUI test results.
When law enforcement cuts corners or when a test doesn’t tell the full story, Arja knows how to bring the truth to light. Whether it’s investigating calibration records, calling expert witnesses, or negotiating with prosecutors, her commitment to personalized, strategic defense sets her apart.
Don’t go through a DUI charge alone. Shah Law Firm offers free, one-on-one consultations so you can understand your options before making any decisions. We are here to stand between you and a conviction.
Call Shah Law Firm today at (602) 560-7408 to schedule your free consultation.
