Witness Testimony in DUI Cases

Phoenix Lawyer for Representing Drivers

Witness testimony in DUI cases can serve as an important form of evidence about the events that led up to your DUI arrest, as well as events that occurred after the arrest. Multiple people may have witnessed the circumstances leading to the traffic stop. Whether you should testify as a witness on your own behalf will be an important decision that should only be made in consultation with a highly experienced attorney. If you are charged with a drunk driving crime, meet with Phoenix DUI defense lawyer James E. Novak. As a former prosecutor, he brings his past work experience to bear on determining the best available strategy to defend clients charged with drunk driving.

Witness Testimony in DUI Cases

Witnesses in DUI cases are called upon to answer questions about what happened. They can include police officers, dispatch, bystanders, passengers in your car at the time of the offense, those with whom you spent time prior to getting in your car, and experts in such matters as chemical testing. For instance, the officer who pulled you over will testify about what she saw prior to pulling you over for suspected drunk driving or another offense. If you were weaving or ran a light, the officer will likely to testify as to that. The officer will likely also testify regarding what she observed during the stop, such as whether your eyes were bloodshot, whether there was alcohol on your breath, and your performance on field sobriety tests.

In some cases, expert witnesses are required on one or both sides. Under Arizona Rule of Evidence 702, an expert can provide testimony in the form of an opinion when: (1) her technical, scientific, or other special knowledge will assist the trier of fact to understand the evidence or determine facts, (2) the testimony is based on enough data or facts, (3) the testimony is the result of reliable methods and principles, and (4) the expert reliably applied methods and principles to the facts in your case. For instance, you might retain an expert to testify about flaws in the procedures used to obtain lab results.

When an expert’s testimony is presented by one side, the other side may present an expert whose opinion counters it. However, the judge presiding over the trial may be able to restrict expert testimony on the grounds that it is irrelevant or not reliable.

In certain situations, it might be appropriate for you to testify on your own behalf. However, you should seek legal counsel to understand the risks involved, such as the potential for self-incrimination. For instance, if you claim that you were not drinking before getting in the car, the prosecutor may question what you were doing, try to catch you in inconsistencies or fluster you. Even if you prepare carefully, your testimony may not go well as you hope. Sometimes, witnesses do not perform well on the stand or become nervous when faced with difficult questions from the other side.


During a trial, the attorneys from both sides will have the opportunity to question witnesses on the stand during cross-examination. Each side may ask initial, direct questions to elicit information that supports its position. However, the other side may try to counter the direct examination with questions that undercut the witness’s information or credibility. The prosecution will try to get witnesses to admit facts that would support a conviction. Likewise, the defense may ask questions that would call into question what the witnesses for the prosecution have testified.

The jury will usually determine the credibility and weight to assign witness testimony, including expert testimony. Witness credibility can have a significant impact on the case. For instance, a witness who contradicts herself about seeing you stagger during a field sobriety test may be shown to lack credibility, and the jury may assign less weight accordingly. The fact finder, which may be the judge or jury, will determine which witnesses are more credible, when their testimonies differ.

Tampering With a Witness

It is crucial not to contact witnesses to influence their testimony in your favor in connection with a DUI. Under Arizona Revised Statute section 13-2804, someone commits witness tampering when he or she knowingly contacts, indirectly or directly, a witness to illegally withhold testimony, testify falsely, remove himself from an official proceeding to which he was lawfully summoned, or evade a subpoena or summons. Tampering with a witness is a separate crime that constitutes a class 6 felony.

Consult a Phoenix Lawyer about Drunk Driving Charges

Witness testimony in DUI cases can play a critical role in the case presented by the prosecution or defense. If you are charged with a DUI, you should consult our principal James E. Novak. He is a seasoned DUI defense attorney who represents those charged in drunk driving in Phoenix, as well as Gilbert, Chandler, Scottsdale, Mesa, Tempe and throughout Maricopa County. Contact him at (480) 413-1499 or complete our online form.

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I was facing criminal charges with three priors in my history. Mr Novak was very helpful and got me a lighter sentence than I probably deserved. He is a great attorney and I would highly recommend him. A. T.
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Attorney Novak did an outstanding job defending my son. Due to his extensive professional background within the court system, he was successfully able to defend my son during a very difficult time for my family. I highly recommend Attorney James Novak for your legal needs. T. G.