Evidence in DUI Cases

Lawyer Defending Phoenix Area Residents in Drunk Driving Cases

Often people assume they will be convicted after a DUI arrest because they had something to drink and drove. However, it isn’t illegal to have a drink and then operate a car. Rather, you must have been impaired by your consumption or alcohol or have a blood alcohol content level of at least .08%. Experienced Phoenix DUI attorney James E. Novak is a former prosecutor who understands how the prosecution will interpret the evidence in your DUI case. He may be able to help you assert your rights and protect your future.

Evidence in DUI Cases

Evidence in DUI cases can include Breathalyzer test results, field sobriety test results, blood tests, and officer testimony about what he or she observed at the time of a DUI stop. Often Breathalyzer tests are used to detect the blood alcohol content of a driver who has been pulled over. The device law enforcement officers use to detect blood alcohol content in this context runs on fuel cell technology or infrared spectroscopy; the device converts how much alcohol is in your breath to a figure that represents the percentage of alcohol in your blood. These procedures are subject to testing errors that can result in unreliable or defective results.

The environment, as well as your particular physical characteristics, such as whether you have GERD, acid reflux, or another medical condition, can also affect the outcome of a Breathalyzer test. As, such, it may be possible to attack the validity of the Breathalyzer test results on these grounds.

Law enforcement officers may have also gathered evidence in the form of field sobriety test results. Field sobriety tests are physical and mental tasks that are administered on the roadside to determine whether you are sober or not; many believe these are inherently defective tests. They include the walk and turn test, the one-leg stand test, the horizontal gaze nystagmus test, and others. If you don’t perform well on a field sobriety test, you may be arrested for a DUI, notwithstanding questions about test validity.

Another type of DUI testing is blood testing. Blood tests may involve altered blood samples, blood contamination, or problems in the chain of custody. They may not have been performed by a properly trained technician, or they may have involved improper storage of the blood sample. The results of blood testing can show error and may be subject to challenge in a motion to suppress. A skilled DUI lawyer can potentially help you challenge your blood test results by getting your blood sample retested by a laboratory in a blood split.

An officer may also testify as to what he observed that gave him probable cause to arrest you for DUI. Signs of intoxication can include red eyes, alcohol on the breath, slurred speech, or difficulty answering questions. In some cases, a drunk driver gets into an accident and is passed out on the scene, and this can result in a DUI arrest with evidence collected without the driver’s participation.


Challenging the prosecution’s evidence may be a critical part of your defense in a DUI case. It is important to look closely at both the evidence and how it was obtained. When evidence is obtained unlawfully, it may be suppressed. For instance, it may be possible to defend against DUI charges on the grounds that there was no reasonable suspicion for a traffic stop, and therefore any evidence from the stop should be suppressed. There may be gaps in the chain of custody, or phlebotomy errors or inappropriate protocols with regard to chemical testing. There may also be improper opinion testimony. In some cases, there is no probable cause to arrest or a denial of Miranda rights has taken place. Under certain circumstances, the police need to collect exculpatory evidence, which means you may have the opportunity to have your own lab analyze a sample.

Dedicated DUI Defense Attorney in Phoenix

If you are concerned about the evidence in a DUI case in Phoenix, you can speak with a seasoned criminal defense lawyer. Mr. Novak defends clients who face prosecution for DUI in and around the Phoenix area, including in Gilbert, Mesa, Chandler, and across Maricopa County. Call him at (480) 413-1499 or contact us via our online form.

Client Reviews
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.
James worked tirelessly behind the scenes with the prosecution, to decrease my son’s charges to a more reasonable penalty. I could not have asked for a better, more professional attorney. He treated my son with the utmost respect and walked him through every step of a very difficult situation. S. G.
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.