DUI with No Valid Breath or Blood Test?

Why a PBT Alone Might Not Be Enough to Convict You in Arizona

If you were arrested for DUI in Pima County or Tucson, Arizona, and the only alcohol test used was a Preliminary Breath Test (PBT), you might be surprised to learn that the prosecution could have a serious evidentiary problem. Unlike blood draws or certified breathalyzer machines used post-arrest, PBTs are not typically admissible in court to prove intoxication. That distinction is critical—and it might be the key to getting your charges reduced or even dismissed.

As a criminal defense and DUI defense attorney in Tucson, I regularly evaluate cases where law enforcement fails to secure legally admissible evidence of intoxication. One of the most common oversights occurs when an officer relies solely on a PBT at the scene and never follows up with a valid, evidentiary test. In these cases, the State often lacks the proof necessary to secure a conviction under Arizona’s DUI laws.

Let’s explore what makes a PBT legally problematic for prosecutors and how a skilled defense attorney can leverage that issue to fight DUI charges in Tucson and Pima County.

What Is a PBT and Why Does It Matter?

A Preliminary Breath Test, or PBT, is a small handheld breathalyzer that officers use in the field, usually during the initial stages of a DUI investigation. The purpose of the PBT is to help officers decide whether they have probable cause to arrest someone for DUI. It is not designed for evidentiary use in court, and it is not held to the same rigorous standards as post-arrest testing.

Under Arizona Administrative Code, a PBT is defined as a device used prior to arrest to obtain a breath sample to determine alcohol concentration. These devices must appear on the National Highway Traffic Safety Administration’s Conforming Products List, but even then, their use is considered non-evidentiary unless specific regulatory requirements are met. According to Arizona law, PBTs do not require an operator permit or adherence to standard operational procedures unless they are intended for evidentiary use—which they rarely are.

This distinction matters because Arizona’s DUI statutes—outline strict foundational requirements for the admissibility of breath test results in court. These include the use of an approved breath testing device, a properly certified operator, duplicate tests with results within 0.02 of each other, a completed operational checklist, and evidence of proper device maintenance. A PBT alone typically does not meet any of these standards.

Legal Precedent Undermining PBT Use in DUI Trials

Arizona courts have repeatedly made clear that only properly administered blood, breath, or urine tests can be used to establish BAC in DUI prosecutions. In State ex rel. Hamilton v. City Court of Mesa, 165 Ariz. 514 (1990), the court emphasized that the Legislature intended only bodily fluid tests to be admissible to establish blood alcohol content. Other tools, such as field sobriety tests or HGN (Horizontal Gaze Nystagmus), might be used to support an officer's suspicion of impairment, but they cannot replace a valid chemical test.

Further, in State v. Quinn, 218 Ariz. 66 (2008), the Arizona Supreme Court reaffirmed that the State has the burden to establish the foundational requirements for the admissibility of test results in DUI prosecutions. Without those foundations, the results must be excluded. In Lyon v. Fell, the court held that breath test results could not be admitted unless the State showed compliance with all statutory and regulatory requirements or otherwise laid an adequate foundation. The case underscored the importance of procedural rigor in breath and blood testing.

Due process concerns also come into play. In Mack v. Cruikshank, 196 Ariz. 541 (1999), the court held that using unreliable testing devices violated due process, and the results were therefore inadmissible. These cases all point to one conclusion: the prosecution cannot use shortcuts. If they want to use a breath test result in court, they have to do it the right way.

What This Means for Your DUI Case in Pima County

If your arrest was based solely on a PBT with no follow-up blood or breath test, the prosecution may have a major hole in its case. Prosecutors will likely attempt to proceed under the theory of impairment to the slightest degree under A.R.S. § 28-1381(A)(1), which doesn’t require a specific BAC. However, even under that statute, the State still needs to prove actual impairment.

Without a valid chemical test, that’s much harder to do. Field sobriety tests may be offered as evidence of impairment, but their reliability is often disputed. The officer’s observations—bloodshot eyes, slurred speech, or the odor of alcohol—are all subjective and easily challenged by an experienced defense attorney.

As a Tucson DUI defense attorney, I often see cases where the officer failed to secure a warrant for a blood draw or never transported the client to a facility with an Intoxilyzer 8000 (the certified evidentiary breath testing machine used in Arizona). Sometimes it’s a matter of poor training; other times, it’s simply a lack of follow-through. Regardless, the result is the same: the prosecution lacks the evidence it needs to secure a conviction.

Using This Defense Strategically in Plea Negotiations

In cases with no valid chemical test, a motion to suppress the PBT result can be a powerful tool. If granted, the prosecution is left with very little to support a DUI conviction. This significantly weakens their bargaining position and opens the door to a favorable plea agreement.

One of the most common resolutions in this situation is a reduction to a charge of Reckless Driving. While still a criminal offense, Reckless Driving carries fewer penalties than a DUI. No interlock device, no mandatory license suspension (in most cases), and no required alcohol screening classes. It’s a pragmatic resolution that allows the court to address the underlying conduct without imposing the harsh consequences of a DUI conviction.

In my practice, I’ve successfully negotiated Reckless Driving pleas in multiple cases where the PBT was the only test conducted. Prosecutors understand the evidentiary limitations and, in many cases, are open to resolution—especially if the defendant has no prior criminal history or aggravating factors.

Why You Need an Experienced Tucson DUI Attorney

Every DUI case is different. The facts, the officer’s conduct, and the specific tests used all affect the strength of the State’s case. But one thing is consistent: the earlier you involve a skilled DUI attorney, the better your chances of identifying weaknesses and using them to your advantage.

If your case involves a PBT and no admissible chemical test, you may have a strong defense. But you need someone who knows how to argue foundational admissibility, who understands how Arizona’s DUI laws intersect with constitutional due process, and who can negotiate effectively with prosecutors in Pima County.

I’ve built my practice around identifying and leveraging precisely these kinds of issues. If you’re facing DUI charges in Tucson or anywhere in Southern Arizona, I encourage you to reach out. We’ll review the evidence together, discuss your legal options, and build a defense strategy tailored to your case.

Schedule a Consultation Today

Facing DUI charges is stressful, but you don’t have to go through it alone. If your arrest involved a PBT with no valid follow-up test, you may be in a better legal position than you think. Contact my office to schedule a consultation and learn how I can help you protect your future.

Amanda Bynum
Criminal Defense & DUI Attorney
AJB Law Firm, LLC
Tucson, Arizona