Arizona Bulletin

When Sober Drivers Are Mistaken For DUI Suspects

Driving under the influence remains one of the most serious road safety problems in the United States, but the tools used to identify impaired drivers are not infallible.

A study by Suzuki Law Officesexamined a lesser-known problem within DUI enforcement: cases in which drivers were arrested or accused of impairment despite later testing showing no alcohol or drugs in their system.

These so-called “sober DUI” cases have been documented in at least 22 states, including Arizona, Tennessee, Hawaii, California, Texas, New York and Florida. In some cases, drivers recorded a blood alcohol concentration of 0.000, tested negative for drugs and ultimately had charges dropped or never filed.

The study also examined the limitations of field sobriety testing, the role of fatigue and medical conditions, and the large differences in DUI arrest rates between states.

One of the clearest findings is that roadside behavior can sometimes resemble intoxication even when alcohol or illegal drugs are not involved.

Sober DUI Cases Have Been Reported In 22 States

Documented sober DUI cases generally share several characteristics: the driver records a 0.000 BAC, alcohol or drugs are not detected, charges are dropped or never filed, or the arrest later becomes the subject of a wrongful-arrest allegation.

Tennessee has recorded the largest documented volume included in the study.

In 2024 alone, 419 sober DUI arrests were reported in Tennessee, bringing the total to 2,547 since 2017.

Hawaii provides another significant example.

Between 2022 and 2024, 127 drivers arrested by Honolulu police later recorded a BAC of 0.000 through breath or blood testing. Only 15 received a traffic citation, while three were charged with drug-impaired driving.

The findings ultimately prompted Honolulu police to review DUI arrests dating back to 2021.

Arizona has also seen multiple cases in which drivers alleged that medical conditions, fatigue or physical limitations were mistaken for impairment.

Arizona Cases Show How Physical Symptoms Can Be Misinterpreted

Several Arizona cases examined by Suzuki Law Offices demonstrate how subjective roadside observations can become part of a DUI arrest.

In one Phoenix case, a California woman alleged she was wrongfully arrested after officers believed she was impaired by THC. Testing later showed no alcohol or drugs.

Another case involved 64-year-old retired firefighter Jesse Thornton, who was arrested after officers observed bloodshot eyes and difficulty with balance.

Thornton recorded a 0.000% BAC, while his balance problems were later attributed to knee and hip conditions. He subsequently filed a $500,000 wrongful-arrest claim.

In another Maricopa County case, a 63-year-old home health aide was arrested after a Drug Recognition Expert interpreted poor balance as evidence of impairment. Blood testing later confirmed sobriety, while work-related fatigue was identified as a possible explanation for the driver's condition.

These cases illustrate a central problem examined in the study: many symptoms associated with intoxication can also have non-alcohol-related explanations.

Field Sobriety Tests Measure Behavior, Not Alcohol Levels

Standardized field sobriety tests were developed to help officers determine whether there is probable cause to believe a driver is impaired.

Three tests are commonly used nationwide:

• Standardized Field Sobriety Test: Horizontal gaze nystagmus— What Officers Evaluate: Involuntary eye movement
• Standardized Field Sobriety Test: Walk-and-turn— What Officers Evaluate: Balance, instructions and coordination
• Standardized Field Sobriety Test: One-leg stand— What Officers Evaluate: Balance and physical control

The horizontal gaze nystagmus test involves tracking an object with the eyes while officers look for specific involuntary movements.

NHTSA's original research found the test had a 77% success ratein identifying drivers with a BAC of 0.10% or higher.

The walk-and-turn test requires a driver to take nine heel-to-toe steps, turn and repeat the process. Two or more observed indicators were associated with a 68% likelihood of a BAC of 0.10% or higher.

The one-leg stand produced a 65% rate under the same standard.

Combined, the horizontal gaze nystagmus and walk-and-turn tests reached an 80% accuracy rate in the original validation studies.

Those numbers also demonstrate why field sobriety tests are not equivalent to chemical evidence. They are designed to help establish probable cause rather than definitively prove that a driver was intoxicated.

Sober Participants Can Still Fail Roadside Tests

More recent research highlights the possibility of false positives.

A 2023 study involving sober participants who received placebos found substantial false-positive rates on standardized field sobriety tests.

• Test: Walk-and-turn— False-Positive Rate Among Sober Participants: 56%
• Test: One-leg stand— False-Positive Rate Among Sober Participants: 37%
• Test: Both tests combined— False-Positive Rate Among Sober Participants: 28%

Almost half, 49.2% of sober placebo participants, were ultimately classified as impaired based on field sobriety testing.

The findings do not mean that field sobriety tests have no enforcement value. Instead, they show that physical performance alone cannot always distinguish alcohol or drug impairment from other conditions affecting coordination, balance or cognition.

Roadside observations, field sobriety testing and chemical testing therefore provide different types of evidence.

A field sobriety test assesses physical and cognitive performance. A toxicology test detects whether certain substances are present. Neither, by itself, necessarily establishes exactly how impaired a person was while driving.

Toxicology Tests Have Limits Of Their Own

Chemical testing may provide stronger evidence of whether alcohol or drugs are present, but it also has limitations.

Drug-testing practices vary significantly between states, including which substances laboratories test for and how samples are analyzed.

A positive result does not always establish current impairment.

Cannabis testing is one example. Detection of certain THC metabolites can indicate previous cannabis use rather than showing that a driver was impaired when stopped.

A negative result can also have limitations if a substance was not included in the testing panel or was no longer detectable when the sample was analyzed.

That makes DUI enforcement particularly complicated when officers suspect drug impairment rather than alcohol impairment.

More Than 800,000 DUI Arrests Were Recorded In 2024

The sober DUI issue exists within a much larger impaired-driving problem.

U.S. law enforcement agencies recorded 804,926 DUI arrests in 2024.

Men accounted for 74.2% of arrests, compared with 25.8% involving women.

The study compared state arrest totals with population to identify where reported DUI arrest rates were highest.

States With The Highest Reported DUI Arrest Rates

• Rank 1 — State: New York— DUI Arrests: 10,598— Rate per 100,000: 53.00
• Rank 2 — State: District of Columbia— DUI Arrests: 288— Rate per 100,000: 41.52
• Rank 3 — State: Rhode Island— DUI Arrests: 259— Rate per 100,000: 23.24
• Rank 4 — State: Tennessee— DUI Arrests: 1,308— Rate per 100,000: 18.00
• Rank 5 — State: North Dakota— DUI Arrests: 107— Rate per 100,000: 13.39
• Rank 6 — State: South Dakota— DUI Arrests: 124— Rate per 100,000: 13.26
• Rank 7 — State: Virginia— DUI Arrests: 1,126— Rate per 100,000: 13.00
• Rank 8 — State: Arkansas— DUI Arrests: 383— Rate per 100,000: 12.30
• Rank 9 — State: Missouri— DUI Arrests: 757— Rate per 100,000: 12.07
• Rank 10 — State: South Carolina— DUI Arrests: 669— Rate per 100,000: 12.01

New York recorded the highest rate in the study at 53 DUI arrests per 100,000 residents.

Tennessee ranked fourth overall, in addition to recording the highest documented volume of sober DUI cases examined.

However, the study makes an important distinction: a high overall DUI arrest rate does not necessarily indicate a high rate of wrongful or sober DUI arrests.

Arizona Ranked Near The Middle Of The Country

Arizona ranked 26th nationally in the study, with a DUI arrest rate of 6.57 per 100,000 residents.

At the lower end of the rankings, several states reported rates below four arrests per 100,000.

States With The Lowest Reported DUI Arrest Rates

• Rank 1 — State: Ohio— DUI Arrests: 201— Rate per 100,000: 1.69
• Rank 2 — State: New Mexico— DUI Arrests: 39— Rate per 100,000: 1.83
• Rank 3 — State: Mississippi— DUI Arrests: 68— Rate per 100,000: 2.30
• Rank 4 — State: Maryland— DUI Arrests: 177— Rate per 100,000: 2.83
• Rank 5 — State: Idaho— DUI Arrests: 59— Rate per 100,000: 2.91
• Rank 6 — State: Florida— DUI Arrests: 770— Rate per 100,000: 3.28
• Rank 7 — State: Alaska— DUI Arrests: 25— Rate per 100,000: 3.39
• Rank 8 — State: Washington— DUI Arrests: 273— Rate per 100,000: 3.41
• Rank 9 — State: Illinois— DUI Arrests: 457— Rate per 100,000: 3.59
• Rank 10 — State: Kansas— DUI Arrests: 119— Rate per 100,000: 4.00

The wide differences illustrate how DUI enforcement varies between states, though arrest rates alone cannot establish how frequently impaired driving actually occurs.

Fatigue Can Resemble Alcohol Impairment

Alcohol and drugs are not the only factors capable of producing erratic driving, slow reaction times or poor performance on roadside tests.

Fatigue can produce many of the same symptoms.

In 2024, 644 people were killed in crashes involving drowsy driving.

These crashes most commonly occur between midnight and 6 a.m. or during the late afternoon. They frequently involve a single driver on a high-speed road and may show little evidence of braking before impact.

Extended periods without sleep can also produce measurable impairment.

• Time Awake: More than 17 hours— Comparable Impairment Effect: 0.05% BAC
• Time Awake: 20 hours— Comparable Impairment Effect: 0.08% BAC
• Time Awake: 24 hours— Comparable Impairment Effect: 0.10% BAC

A driver awake for 20 consecutive hours can therefore experience impairment comparable to the 0.08% legal alcohol limit.

Crash risk also increases sharply as sleep decreases.

Drivers who sleep six to seven hours per night are twice as likely to be involved in fatigue-related crashes as those receiving at least eight hours. Drivers sleeping fewer than five hours face a crash risk four to five times higher.

For night-shift and extra-shift workers, the combination of exhaustion, poor balance, slowed reactions and red or tired eyes can potentially resemble alcohol or drug impairment during a traffic stop.

Diabetes And Other Medical Conditions Can Mimic Intoxication

Medical conditions create another possible source of confusion.

An estimated 40.1 million Americans had diagnosed or undiagnosed diabetes in 2023, including approximately 11 million adults who had not been diagnosed.

Low blood sugar can produce symptoms including dizziness, confusion, shaking, fatigue, blurry vision, seizures and behavioral changes.

Several of those symptoms may resemble impairment.

Testing can also be complicated in some cases. Elevated acetone levels associated with diabetes may be misidentified as ethanol by certain breath or urine tests.

One study involving people with type 1 diabetes found that 42.9% recorded breathalyzer readings above legal limits, despite many participants having consumed no alcohol.

The findings demonstrate why medical history can become relevant when physical symptoms and chemical testing do not align.

Legal Medications Can Complicate Impairment Assessments

Prescription and over-the-counter medications can also affect driving or drug screening.

Common side effects include drowsiness, blurred vision, dizziness, impaired concentration and slowed reaction time.

Medications capable of producing these effects include opioids, benzodiazepines, muscle relaxants, sleeping medications, antidepressants and antihistamines.

Some substances may also complicate preliminary drug screening.

The study identified several examples, including:

• Ibuprofen potentially producing false-positive THC results
• Amoxicillin occasionally being associated with cocaine false positives
• Sertraline and trazodone interfering with some amphetamine or benzodiazepine screenings
• Pseudoephedrine and some diet medications screening as amphetamines

Products containing alcohol or related compounds, including certain cough syrups, throat medications, oral gels and inhalers, can also affect testing in some circumstances.

A national roadside survey found that 10% of daytime drivers tested positive for prescription or over-the-counter drugs, highlighting how common legal medications are among people behind the wheel.

Arizona’s Implied Consent Law Can Create Consequences Before A Case Is Resolved

Arizona presents an additional complication because of its implied consent law.

Drivers must submit to chemical testing when an officer establishes probable cause. Refusing the test can trigger an automatic 12-month license suspension.

That means drivers suspected of impairment may undergo blood testing even when they maintain that they are sober.

When later testing clears a driver and criminal charges are dismissed, administrative licensing consequences can still require additional action to resolve.

For someone incorrectly suspected of DUI, the process can therefore extend beyond the original traffic stop and continue even after chemical evidence shows no alcohol or drugs.

Wrongful DUI Cases Expose The Limits Of Roadside Assessment

The findings assembled by Suzuki Law Offices reveal two road-safety realities that can exist at the same time.

Impaired driving remains a major threat. Nearly 12,000 people died in alcohol-impaired crashes in 2024, and more than 800,000 DUI arrests were recorded nationwide.

But accurately identifying impairment can be complicated.

Sober DUI cases have been documented in at least 22 states. Tennessee recorded 419 such cases in 2024 alone, while 127 Honolulu drivers arrested between 2022 and 2024 later recorded 0.000 BAC results.

At the same time, controlled research found that 49.2% of sober placebo participants were classified as impaired during field sobriety testing, while fatigue, physical disabilities, diabetes and legal medications can all produce symptoms that resemble intoxication.

The distinction matters because roadside testing is designed to help officers make decisions under uncertain conditions, not to provide a perfect measurement of impairment.

For drivers who are intoxicated, effective enforcement remains an essential part of road safety. For drivers who are not, however, the same system can carry serious consequences when physical symptoms, fatigue or medical conditions are mistaken for evidence of alcohol or drug use.