A DUI can be dismissed in Arizona if the defense identifies constitutional violations during the traffic stop, procedural errors in chemical testing, or breaks in the chain of custody for blood samples. Arizona courts have suppressed DUI evidence when officers lacked reasonable suspicion for the initial stop, failed to observe the mandatory 15-minute deprivation period before breath testing, or used improperly calibrated Intoxilyzer 8000 devices. Call Oliverson Law at (480) 582-3637 to evaluate your case.
Legal Grounds for DUI Dismissal in Arizona
Arizona DUI law under ARS 28-1381 requires the prosecution to prove two things beyond a reasonable doubt: that you were operating or in actual physical control of a vehicle, and that you were impaired to the slightest degree or had a BAC at or above the applicable threshold (0.08% for standard, 0.15% for extreme, 0.20% for super extreme). A DUI charge can be dismissed if the defense successfully challenges either element.
Dismissal can occur at several stages: the prosecutor may dismiss before trial if evidence problems are identified, the judge may suppress evidence through a pretrial motion (effectively forcing dismissal), or the judge may grant a directed verdict at trial if the prosecution fails to meet its burden of proof.
The most common grounds for dismissal fall into three categories: problems with the traffic stop, errors in chemical testing procedures, and constitutional violations during the arrest process.
Challenging the Traffic Stop
Under the Fourth Amendment, a law enforcement officer needs reasonable suspicion that a traffic violation or crime has occurred in order to initiate a traffic stop. This is a lower standard than probable cause but still requires specific, articulable facts — not a hunch.
Common reasons officers cite for DUI-related traffic stops include weaving within or between lanes, driving at an unusually slow speed, failing to maintain a single lane, running a red light, or having equipment violations such as a broken taillight. If body camera or dashcam footage shows the officer initiated the stop without observing any traffic violation or suspicious driving behavior, the stop itself may be unconstitutional.
When a judge rules that a traffic stop was unconstitutional, all evidence obtained as a result of that stop — including field sobriety test results, breath test results, blood test results, and officer observations — is suppressed under the exclusionary rule. Without this evidence, the prosecution typically cannot sustain the DUI charge and must dismiss.
Chemical Testing Errors
Arizona uses two primary methods for measuring blood alcohol concentration: breath testing with the Intoxilyzer 8000 and blood draws analyzed at the Arizona Department of Public Safety crime lab or an approved private laboratory.
Breath Testing Issues
The Intoxilyzer 8000 requires regular calibration according to manufacturer specifications and Arizona DPS protocols. Defense attorneys can request calibration and maintenance records for the specific device used. If the device was overdue for calibration, produced inconsistent readings across sequential tests, or had documented error codes, the results may be challenged.
Arizona also requires officers to observe the suspect continuously for at least 15 minutes before administering a breath test (the deprivation period). During this period, the suspect should not eat, drink, smoke, vomit, or place anything in their mouth, as these actions can introduce mouth alcohol that falsely inflates the reading. If the officer was distracted, left the room, or did not maintain continuous observation, the defense can challenge the test results.
Blood Testing Issues
Blood samples must follow a documented chain of custody from the draw site to the laboratory. Each person who handles the sample must be documented. The sample must be stored at appropriate temperatures and analyzed within the established time window. Issues that can arise include:
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What to Do If You Want to Fight Your DUI Charge
Request the MVD Hearing Within 15 Days
After receiving the Admin Per Se affidavit, you have 15 calendar days to request an administrative hearing with the Arizona MVD. This hearing is separate from the criminal case and addresses your license suspension. Missing this deadline means the suspension takes effect automatically.
Obtain All Evidence From the Prosecution
Through the discovery process, your attorney requests the complete police report, body camera and dashcam footage, breathalyzer calibration records, blood test lab reports, chain of custody documentation, and any witness statements. This evidence forms the foundation of every defense strategy.
Identify Procedural and Constitutional Errors
An experienced DUI defense attorney reviews every step of the arrest and testing process to identify violations of your rights or failures to follow required procedures. Even small procedural errors can lead to evidence suppression.
File Motions or Negotiate With the Prosecutor
If constitutional or procedural errors are identified, the defense files motions to suppress evidence. When key evidence is suppressed, prosecutors often dismiss or reduce charges. Alternatively, evidence weaknesses can be leveraged during plea negotiations to achieve a more favorable outcome.
Mistakes That Hurt Your Chances of Dismissal
Related Questions
There is no single published statewide dismissal rate for Arizona DUI cases. Dismissal rates vary significantly by jurisdiction, the strength of the evidence, the specific facts of each case, and the quality of the defense. Cases involving constitutional violations during the traffic stop, testing procedure errors, or chain of custody problems have stronger grounds for dismissal than cases with clean evidence. An attorney can evaluate the specific facts of your case to assess the available defense options.
Arizona prosecutors may agree to reduce a DUI charge to reckless driving or another lesser offense through plea negotiations, particularly when the evidence has weaknesses that create risk for the prosecution at trial. A reckless driving conviction avoids the mandatory ignition interlock device requirement and carries less stigma than a DUI conviction. However, this outcome depends on the specific facts of the case, the prosecutor assigned, and the jurisdiction. It is not guaranteed in any case.
Refusing a chemical test under Arizona’s implied consent law (ARS 28-1321) results in an automatic license suspension of 12 months for a first refusal and 2 years for a subsequent refusal within 84 months. While refusal means there is no BAC number for the prosecution to use, the prosecution can still pursue DUI charges based on officer observations of impairment, field sobriety test performance, and other evidence. The refusal itself can also be presented to the jury as evidence of consciousness of guilt.
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