DUI Trial Defense Strategies

When a DUI Case Goes to Trial in Utah

Taking a DUI case to trial means asking a jury or judge to evaluate the prosecution's evidence and decide whether the state has proven guilt beyond a reasonable doubt. Trial is the right path when the evidence weaknesses are strong enough to create a genuine chance of acquittal, when the prosecution's plea offer fails to account for those weaknesses, or when the consequences of a conviction are severe enough that fighting the charge is worth the risk. Not every DUI case should go to trial, but the cases that do require an attorney who has the trial experience and technical knowledge to execute a defense strategy under courtroom conditions.

Glen Neeley has tried DUI cases before juries across Utah since 1998. His board certification in DUI defense and role as faculty at the National College for DUI Defense reflect a practice focused on the scientific and procedural complexities that DUI trials demand. Trial preparation in our office begins at case intake because the evidence analysis, witness development, and expert retention that drive a successful trial cannot be assembled at the last minute.

Deciding Whether Trial Is the Right Strategy

The decision to take a DUI case to trial is not made on instinct. It is based on a methodical assessment of the evidence, the available defenses, the assigned judge, the likely jury pool, and the range of outcomes at trial versus the terms of any plea offer. A case with a clearly unlawful traffic stop, for example, may be strong for trial if the suppression motion is denied but the evidence of the stop's illegality is compelling enough to create reasonable doubt before a jury.

Cases involving BAC results close to Utah's .05 threshold often present strong trial opportunities because measurement uncertainty and rising blood alcohol defenses become viable. A defendant whose BAC tested at .06 at the station may have been below .05 at the time of driving if blood alcohol was still rising during the absorption phase. Presenting this science to a jury requires both the expert witness to explain it and the trial attorney to frame it within the broader defense narrative.

We discuss the trial decision candidly with every client. That conversation includes the best realistic outcome at trial, the worst realistic outcome, and how those compare to the plea offer on the table. Clients make informed decisions when they understand the actual probabilities, not when they are given vague assurances.

Challenging the Traffic Stop

Every DUI case begins with a traffic stop or encounter, and the legality of that stop is the foundation of the prosecution's case. Under the Fourth Amendment and Article I, Section 14 of the Utah Constitution, law enforcement must have reasonable articulable suspicion that a traffic violation or criminal activity has occurred before stopping a vehicle. If the officer cannot demonstrate that suspicion, the stop is unlawful and the evidence collected afterward is tainted.

At trial, the defense cross-examines the arresting officer about the specific observations that prompted the stop. Dashcam footage often contradicts the officer's report. An officer who writes that the vehicle was weaving may be contradicted by video showing the vehicle maintaining its lane with only minor corrections. The gap between the written report and the recorded reality is a powerful trial tool because it undermines the officer's credibility on everything that followed.

DUI checkpoint stops involve different constitutional requirements. Under Utah law, checkpoints must follow specific operational guidelines to be valid. If the checkpoint failed to comply with these requirements, the stop can be challenged even though no individual reasonable suspicion was required.

Attacking Field Sobriety Test Evidence

Standardized field sobriety tests, including the horizontal gaze nystagmus test, the walk-and-turn test, and the one-leg stand test, are administered during nearly every DUI arrest. At trial, the prosecution presents these tests as objective evidence of impairment. The defense challenges both the administration and the interpretation of these tests.

The National Highway Traffic Safety Administration published specific protocols for administering each test. When officers deviate from these protocols, the test results lose their scientific validity. Conducting the walk-and-turn test on a sloped surface, failing to demonstrate the test properly, not accounting for the subject's footwear, or administering the tests under poor lighting conditions all compromise the results. Glen has completed the same NHTSA standardized field sobriety test training that officers undergo, which allows him to identify exactly where the administration departed from the required protocol.

Medical conditions also affect field sobriety test performance. Inner ear disorders, neurological conditions, musculoskeletal injuries, and certain medications can produce the same physical signs that officers interpret as impairment. Presenting this evidence at trial requires medical records and, in some cases, expert testimony from a physician or neurologist.

Challenging Breath Test Results

Breath test evidence is the centerpiece of most DUI prosecutions, and it is also one of the most vulnerable categories of evidence at trial. The Intoxilyzer instruments used in Utah measure breath alcohol and convert it to an estimated blood alcohol concentration using a standard partition ratio. That conversion introduces inherent measurement uncertainty that the prosecution rarely acknowledges.

At trial, the defense attacks breath test reliability on multiple fronts. Calibration records may reveal that the instrument was outside its acceptable tolerance range. Maintenance logs may show that repairs or adjustments were made around the time of the test. The officer's failure to observe a continuous 15-minute deprivation period before testing can allow residual mouth alcohol to inflate the reading. Medical conditions such as gastroesophageal reflux disease can produce artificially elevated breath test results by introducing stomach alcohol into the breath sample.

Glen's NCDD training includes the same Intoxilyzer operation courses that breath test operators complete. That training allows him to cross-examine the breath test operator on the instrument's limitations and to present expert testimony that explains these limitations to the jury in accessible terms.

Challenging Blood Test Results

Blood tests are generally considered more accurate than breath tests, but they are not immune to challenge. The defense examines the entire chain of custody from the blood draw to the laboratory analysis. Was the blood drawn by a qualified phlebotomist? Were the collection tubes properly preserved with the correct anticoagulant and preservative? Was the sample stored at the appropriate temperature? Was the laboratory's analytical method validated for the sample type?

Fermentation is a recognized issue with improperly preserved blood samples. If insufficient sodium fluoride preservative was used, or if the sample was stored at elevated temperatures, bacteria can metabolize glucose in the blood and produce alcohol that was not present at the time of the draw. Independent retesting of the blood sample, when available, can reveal discrepancies between the original laboratory result and the actual alcohol content.

Rising blood alcohol is another defense relevant to blood test cases. If the blood draw occurred 30 to 90 minutes after the traffic stop, the defendant's BAC at the time of the draw may have been higher than at the time of driving. Forensic toxicology experts can calculate retrograde extrapolation to estimate what the BAC was at the time of driving based on drinking pattern, body weight, and the time elapsed.

Jury Selection in DUI Trials

Jury selection, formally called voir dire, is one of the most consequential phases of a DUI trial. Prospective jurors bring personal experiences, biases, and assumptions about alcohol, driving, law enforcement, and the justice system. Identifying jurors who can apply the presumption of innocence and hold the state to its burden of proof is essential to a fair trial.

During voir dire, the defense questions jurors about their willingness to acquit if the prosecution fails to prove its case beyond a reasonable doubt, even if they believe the defendant probably committed the offense. Jurors who cannot distinguish between "probably guilty" and "guilty beyond a reasonable doubt" are not suitable for a DUI trial. Experienced trial attorneys also identify jurors with connections to law enforcement, personal experiences with alcohol-related incidents, or strong opinions about DUI enforcement that could prevent impartial deliberation.

Expert Witnesses at Trial

DUI trials frequently involve expert witness testimony on both sides. The prosecution may call the breath test operator, a toxicologist from the state crime lab, or the officer who administered field sobriety tests. The defense retains independent experts to challenge this testimony and present alternative interpretations of the evidence.

Defense experts in DUI cases may include forensic toxicologists who testify about blood alcohol metabolism, partition ratio variability, and retrograde extrapolation. Instrument specialists can testify about the limitations of the specific breath test device. Medical experts can explain how a client's health condition affected field sobriety test performance or produced symptoms the officer mistakenly attributed to intoxication.

Retaining and preparing expert witnesses requires advance planning. Experts need time to review the evidence, prepare their opinions, and develop testimony that a jury can understand. This is why trial preparation begins early in our office, not in the weeks before the trial date.

Contact Our Office About Your DUI Case

If you are considering taking your DUI case to trial in Utah, or if you want to understand whether trial is the right strategy for your situation, contact our office. We will review the evidence, assess the trial viability, and give you a candid evaluation of the options available.