Generally, a DUI is considered a misdemeanor criminal offense. So, anyone who's accused of driving under the influence typically has a right to a jury trial. (The procedures for minor traffic violations are normally different.) Most criminal cases, including those involving DUI charges, don't actually go to trial but are instead resolved through plea bargaining. But if you do end up taking a DUI case to trial, here's what to expect.
Anyone who's charged with a crime is normally entitled to a jury trial. But, occasionally, a criminal defendant will waive the right to a jury trial and opt for a trial by judge (also called a "bench trial") instead. The difference here is who will be deciding the defendant's guilty—a group of jurors or a single judge.
Defense attorneys sometimes have specific reasons for thinking they're chances of winning are better in a particular case with a bench trial. However, in the majority of cases, defense attorneys prefer jury trials. (With minor traffic violations, in contrast, a bench trial is usually on the only option.)
The first thing that needs to happen for a jury trial is jury selection. Jury selection is just the process for choosing who will be the jurors deciding the case. The process begins with the defense and prosecution questioning potential jurors who are in the "jury pool"—the group of citizens who report for jury duty for the case. Essentially, each side gets to dismiss jurors they don't want on the case with certain restrictions. For instance, the defendant's constitutional rights prohibit the prosecution from dismissing jurors for discriminatory reasons involving race, ethnicity, and gender discrimination.
Jury selection can take quite a while. But eventually, through this process of elimination, the defense and prosecution will end up with the jurors who will decide the case. The judge will then "swear the juror in" and move on to the next phase of the trial.
Before presenting any evidence, the defense and prosecution get to make opening statements to the jurors. The official purpose of opening statements is for the parties to tell the jurors what they believe the evidence will show.
In a DUI trial, the prosecution will typically outline how they intend to prove the DUI charges. In other words, the prosecution will explain who they plan to call as witnesses and the other types of evidence they're going to present to back up the charges. The defense might also inform the jurors of evidence and witnesses they anticipate presenting at trial. But in many cases, the opening statement of the defense focuses primarily on where they think the prosecution's evidence will come up short.
At a DUI trial (or any other criminal trial), the prosecution has the "burden" of proving the charges against the defendant "beyond a reasonable doubt." In other words, the prosecution must present sufficient evidence at trial to convince the jurors of the defendant's guilt. If the prosecution can't accomplish this, the presumption of innocence requires the jurors to find the defendant not guilty.
Having the burden of proof, the prosecution needs to do the heavy lifting at trial and will present their evidence first. The circumstances of each case are different. But at a DUI trial, the prosecution's evidence often includes the testimony of the arresting officers and chemical test results showing how much alcohol or what drugs were in the driver's system at the time of the arrest.
The defense gets to cross-examine the prosecution's witness and might object to the admission of the prosecution's evidence. And, when the prosecution "rests its case," the defense can present evidence of its own. In many DUI cases, the pivotal issue is whether the defendant's blood alcohol concentration (BAC) exceeded the legal limit of .08% (.05% or more in Utah) at the time of the arrest. So, it's pretty common for the defense to call an expert to testify who can cast doubt on the reliability of the prosecution's BAC test evidence.
In most DUI cases, the presentation of evidence from both sides doesn't take more than a day or two.
Once the parties finish presenting their evidence, it's time for closing arguments. Typically, the prosecution will use this opportunity in a DUI case to go back over the evidence and explain how the evidence supports the charges. The defense will basically do the opposite and try to point out any deficiencies in the prosecution's case and highlight any areas that might give rise to doubt of the defendant's guilt.
The closing argument is typically an attorney's last chance to address the jurors directly for they decide the case.
The final phase of a DUI trial involves the judge informing the jury of the relevant law (called "jury instructions") and the jurors getting together and making an actual decision on guilt (called "deliberations").
If the jurors are able to come to a consensus, a foreperson from the jury will inform the judge that they've reached a verdict. The judge will then call everyone back into the courtroom, and the foreperson will read the verdict of guilty or not guilty.
When the jurors are unable to agree on a unanimous verdict, the judge will normally declare a "mistrial." A mistrial basically means the defendant was neither convicted nor acquitted of the charges. Typically, the prosecution can opt to retry a case following a mistrial.