The thumbnail’s message — “THE TEST PROVED IT! THEY GOT IT WRONG” — reflects a real issue in impaired-driving investigations: what happens when the evidence collected later does not support what officers initially believed?

A BREATH TEST CAN CHANGE THE ENTIRE INVESTIGATION

According to the NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION (NHTSA), law enforcement uses two broad categories of breath-testing equipment.

PRELIMINARY BREATH TESTS (PBTs) are generally portable screening devices used during roadside investigations. More formal EVIDENTIAL BREATH TEST (EBT) instruments are approved for evidentiary use and can be portable or stationary.

That distinction matters.

A roadside breath device is not necessarily the final word in a DUI case. Officers may consider the reading together with DRIVING BEHAVIOR, FIELD SOBRIETY TESTS, statements from the driver, physical observations, and other evidence.

NHTSA also acknowledges that preliminary breath testing has ACCURACY AND EVIDENTIARY LIMITATIONS. Factors such as residual mouth alcohol and improper use can affect readings. The legal significance of a PBT also varies from state to state.

So when a device displays 0.00, it can be an important piece of evidence—but investigators may still examine whether another substance could explain suspected impairment.

A REAL CASE INVOLVING A 0.00 RESULT

A particularly striking example came from IOWA.

Tayvin Galanakis was stopped by Newton police in 2022 after officers observed him driving with his high beams on. During the stop, officers conducted several field sobriety exercises.

Galanakis eventually took a breath test.

The result was 0.00 BAC.

Despite that result, officers continued investigating the possibility that he was impaired by marijuana. He was eventually arrested for operating while intoxicated, but a later drug evaluation found that he was not impaired by illicit substances.

The case later reached the U.S. COURT OF APPEALS FOR THE EIGHTH CIRCUIT.

In 2025, the appeals court held that the officers were not entitled to qualified immunity on Galanakis's Fourth Amendment claim, concluding that the evidence described in the record did not provide an objectively reasonable basis for concluding there was a substantial chance he had driven while under the influence of marijuana.

Then, in June 2026, a federal jury awarded Galanakis $105,000 in damages following a civil trial concerning the arrest.

The case demonstrates why a clean breath test does not automatically end every impaired-driving investigation—but also why investigators must have evidence supporting the particular impairment theory they pursue.

0.00 DOES NOT ALWAYS MEAN “NOTHING ELSE IS POSSIBLE”

There is an important distinction between ALCOHOL IMPAIRMENT and DRUG IMPAIRMENT.

A breath test is designed primarily to detect alcohol. A result of 0.00 means the particular test did not detect alcohol at the measured level. It does not function as a universal test for every substance that could potentially affect driving.

NHTSA recognizes that impaired-driving enforcement can involve ALCOHOL, ILLICIT DRUGS, prescription medications, or combinations of substances.

That means an officer who receives a 0.00 alcohol reading might still investigate another possible explanation—but that additional investigation should be based on specific evidence rather than simply assuming that a person must be impaired because the officer initially suspected it.

The Galanakis case illustrates exactly why this distinction matters.

ANOTHER CASE: WHEN A CLEAN TEST CAME TOO LATE

In Colorado, Jesse Cunningham experienced a different version of the problem.

In 2021, Cunningham stopped to help after witnessing a serious motorcycle crash in Fort Collins. According to reporting by CBS Colorado, he told an officer that he had consumed two beers several hours earlier.

The officer suspected DUI and conducted roadside sobriety testing.

Cunningham repeatedly asked for a breath test.

Instead, he was arrested and taken for a blood test. Laboratory results later showed NO ALCOHOL OR DRUGS in his blood, and prosecutors dismissed the criminal case.

In July 2026, the City of Fort Collins agreed to pay Cunningham $500,000 to settle his lawsuit.

The settlement does not mean every allegation made during the original arrest was legally proven. But the laboratory results and subsequent litigation show how dramatically an impaired-driving case can change when objective testing becomes available.

WHY FIELD SOBRIETY TESTS CAN CREATE QUESTIONS

One of the most important parts of a DUI investigation can occur before the breathalyzer ever appears.

Officers may conduct STANDARDIZED FIELD SOBRIETY TESTS, including exercises involving walking, standing on one leg, and eye movements.

These tests are intended to help officers identify possible impairment. But they are performed in real-world conditions—not in a laboratory.

Weather, road surfaces, footwear, nervousness, medical conditions, fatigue, age, and misunderstanding instructions can potentially affect performance.

That does not mean field sobriety tests are useless. Rather, they are one component of an investigation.

When a driver appears unsteady but subsequently produces a 0.00 ALCOHOL RESULT, investigators may need to determine whether the behavior has another explanation.

BODY-CAMERA FOOTAGE CAN BECOME CRITICAL EVIDENCE

Modern DUI investigations increasingly involve BODY-WORN CAMERAS.

That footage can preserve what actually happened during a traffic stop: how instructions were given, how a driver responded, how field sobriety tests were performed, what the officer observed, and what happened immediately before and after a breath test.

In Galanakis’s case, video evidence became particularly significant during the later legal proceedings because the parties disputed how his performance during the stop should be characterized.

This is one reason objective evidence can be so important in criminal investigations.

A written report may describe an event in one way. A video recording may provide additional context.

A laboratory result may then provide another piece of the puzzle.

A CLEAN TEST IS POWERFUL—BUT CONTEXT STILL MATTERS

It would be a mistake to say that every 0.00 BREATH TEST automatically proves that a DUI arrest was unlawful.

The law differs between jurisdictions, and officers may have additional evidence suggesting impairment by drugs or another substance.

Likewise, a breath test itself must be interpreted according to the type of device used, its procedures, calibration, timing, and applicable state law.

NHTSA states that properly calibrated and maintained evidential breath instruments are important tools for law enforcement, while also noting that impaired-driving investigations rely on multiple factors rather than a breath result alone.

The key issue is therefore EVIDENCE.

Was the original suspicion supported by observable facts?

Were the tests properly administered?

Did later chemical testing support or contradict the initial theory?

Was there evidence of drugs or another impairing substance?

And, ultimately, did the available evidence establish the legal basis required for the action taken?

WHEN THE EVIDENCE CHANGES THE STORY

The most important lesson from cases involving 0.00 BREATH TESTS is that an initial suspicion is only the beginning of an investigation.

Technology can challenge assumptions.

BREATH TESTS, BLOOD TESTS, DRUG EVALUATIONS, BODY-CAMERA FOOTAGE, and other evidence can either strengthen an investigation or raise serious questions about what happened.

In the Galanakis case, the initial suspicion of impairment developed into years of litigation after testing showed 0.00 alcohol and a later drug evaluation found no impairment. In the Cunningham case, laboratory testing ultimately showed no alcohol or drugs after his DUI arrest.