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Challenging DUI Chemical Tests in Arizona

If you or someone you love has been arrested for driving under the influence (DUI) in Arizona, you may have been subjected to one or more chemical testing procedures during your arrest. These chemical tests, in addition to other field sobriety tests, are a police officer's efforts to prove you were intoxicated while driving.

Chemical tests are notoriously inaccurate. Just because you have been charged with DUI does not mean you are guilty, and there are legal challenges that can be made to the chemical tests used in your arrest. With the help of an experienced Arizona DUI attorney, you can challenge the results of these tests to possibly lower or even dismiss the charges against you.

Challenging DUI Testing Procedures

After an Arizona police officer arrests a driver for suspected DUI, he will administer a chemical test meant to determine whether, and at what level, you were under the influence of alcohol or drugs. Understanding what these tests are, and how they can be challenged is important to your defense.

Breath Testing

The breath test most people are familiar with is known as a preliminary breath test (PBT). This test is taken at the location of the traffic stop using a handheld device that measures the driver's blood alcohol content (BAC). In Arizona, a BAC above 0.08% is considered sufficient probable cause for a DUI arrest of a suspect. However, Arizona is a zero-tolerance state, meaning that any influence of alcohol or drugs while driving may result in prosecution.

Preliminary breath test devices do not store quality assurance records, meaning an analysis of test accuracy cannot be determined. Further, these handheld devices are not subject to periodic maintenance. However, while a PBT is sufficient probable cause for an arrest, the results are not admissible in a criminal or civil proceeding to suspend your driver's license.

Under Arizona's implied consent laws, a second breath test is administered to determine whether the driver is above the legal limit. This breath test, considered more accurate than the PBT, can be used as evidence against you at trial or another proceeding which could impact your driving privileges. Periodic maintenance and quality assurance records are required for these tests.

Both tests may also inaccurately reflect intoxication when the driver has recently used mouthwash or breath spray. To challenge breath tests in Arizona, your attorney can argue:

  • That the PBT did not accurately reflect the driver's BAC, leading to an improper arrest;
  • That the implied consent test was not properly maintained;
  • That the quality assurance records indicate the test's inaccuracy;
  • That the officer who administered the test was not properly trained in its use;
  • The suspect suffered from gastric reflux or other medical condition which may affect the results of the test;
  • Failure of police officers to observe the 20-minute observation period. Police must carefully and continuously observe the DUI suspect prior to administering the breath test. If the suspect burps, vomits, or eats or drinks anything it may affect the accuracy of the breath reading.

Successfully challenging the results of your breath test can be an important part of your legal defense. The experienced attorneys at the law offices of Shawn B. Hamp can raise these defenses for you.

Blood Testing

After your DUI arrest, you may be required to give a blood sample. Blood samples can reflect the amount of alcohol by determining your BAC, but this procedure is more commonly used when law enforcement suspects that a driver is under the influence of drugs. Blood tests are generally more accurate than breath tests, but certain issues still exist.

Arizona uses special kits which contain a vacuum tube coated with specific chemicals which prevent coagulation and preserve the blood sample. Officers then follow a set protocol to mix the blood sample with the chemicals by rotating the tube end to end five times. After that, the officer rotates the tube an additional 20 times.

Blood tests may be challenged by showing:

  • That the alcohol swab contaminated the blood sample;
  • The blood kit, often a NIK kit, is expired;
  • Improper proportions of chemicals were used;
  • The officer did not follow the mixing protocol correctly;
  • The officer who conducted the test was not properly trained or certified;
  • Testing only the serum or plasma instead of the whole blood;
  • The driver has diabetes or high blood ketones which may create a false positive;
  • Issues with the chain of custody;
  • Improper maintenance or storage of the blood sample.

If any of the above can be shown in court, it is possible that the blood testing results may be deemed inadmissible. This may result in your charges being lowered or dropped in some cases.

Urine Testing

Urine testing is considered inherently unreliable, and as a result, the State of Arizona does not typically rely on urine tests to prove intoxication in a DUI case. However, urine tests are more often used to determine whether you were under the influence of drugs while you were driving.

Urine testing does not measure BAC, it instead estimates the amount of alcohol or drugs in the blood based on average presence in the urine. To conduct a urine test, an officer will transport you to a certified detention facility which can conduct a DUI urine test. The test must be performed by someone certified to conduct the procedure.

There are several ways to challenge the validity of DUI urine test results, such as:

  • DUI test results can be challenged based on how recently urination took place from the arrest;
  • When the procedure was performed by someone not certified to conduct the test;
  • Laboratory error;
  • Variation of alcohol content in urine can greatly vary from person to person;
  • Argue that the estimate does not sufficiently prove intoxication.

Experienced DUI Attorneys in Arizona

Challenging the tests used during your arrest is a crucial part of your defense in a DUI case. Whether this is your first DUI offense, or a subsequent offense, facing criminal prosecution can be frightening and can result in serious consequences including loss of your license, fines, or prison.

If you have been arrested and charged with DUI in Arizona, do not assume you are guilty. The attorneys at the law offices of Shawn B. Hamp have the years of experience needed to fight for your rights. We serve clients in Mohave, Yavapai, La Paz, and Coconino Counties, including the communities of Kingman, Bullhead City, Lake Havasu, Parker, Prescott, Williams and Flagstaff, Arizona. Contact us today for a free consultation.

Contact Us Today

If you have been arrested or charged with a crime you may be feeling frightened, anxious, and uncertain of what your future holds. The competent and experienced attorneys at the Law Offices of Shawn B. Hamp can help you during this difficult time. We are dedicated to fighting for the rights of our clients and providing excellent legal representation to those who have been accused of a crime. Contact our firm today to discuss your case in a free case consultation.

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