When a person is pulled over on suspicion of driving under the influence in Flagstaff, they may be asked to submit to blood alcohol testing to determine their blood alcohol concentration (BAC). The results of these tests can have significant legal implications, potentially leading to DUI charges and harsh penalties.

The experienced team of attorneys at Griffen & Stevens Law Firm, PLLC, a respected Flagstaff DUI legal firm, has extensive knowledge about the different blood alcohol testing methods, their accuracy, and potential challenges to BAC evidence. Understanding these aspects is crucial for anyone facing DUI charges based on blood alcohol test results.

3 Common BAC Testing Methods in Arizona Blood Alcohol Testing Methods | Flagstaff DUI Lawyer

In Arizona, law enforcement primarily uses these methods to measure a driver's BAC.

1. Breathalyzer Tests

Breathalyzers indirectly estimate BAC by measuring the amount of alcohol in a person's breath. The driver blows into the device, which calculates the corresponding BAC. Due to their convenience and quick results, breathalyzers are the most common roadside field sobriety testing method. 

However, breathalyzer accuracy can be affected by factors like calibration issues, user error, the presence of mouth alcohol, and certain medical conditions. One of our experienced DUI attorneys may be able to challenge the results based on these potential issues.

2. Blood Tests

Blood testing directly measures the amount of alcohol in a driver's bloodstream, providing a more accurate BAC reading than breath tests. In Arizona, blood draws must be performed by a qualified professional, usually at a police station, hospital, or mobile phlebotomy service. 

While blood test results are generally more reliable, there are still opportunities for error. Improper storage, contamination of the sample, and issues with the chain of custody could all be grounds for challenging blood test evidence. Our skilled DUI lawyers make a point to thoroughly review the testing procedures.

3. Urine Tests 

This is the least common method for determining BAC in Arizona DUI cases. Like breath testing, it provides an indirect measurement that can be less precise than blood testing. Urine tests may be used if a breath or blood test is unavailable or the driver has a medical condition preventing other testing methods.

Urine test accuracy varies based on factors like an individual's hydration level, bladder function, and the timing of the sample collection. These variables often make it easier for our knowledgeable DUI attorneys to dispute urine test results in court.

Legal BAC Limits in Arizona

Arizona law specifies different BAC limits for DUI charges based on a driver's age and license type:

  • 0.08%. The legal limit for drivers 21 years and older operating regular passenger vehicles.
  • 0.04%. The legal limit for commercial driver's license holders operating commercial vehicles. 
  • 0.00%. As stated under ARS Section 4-244(34), there’s a zero-tolerance policy for drivers younger than 21 years old.

Penalties for exceeding these limits can include fines, license suspension, mandatory ignition interlock device installation, and even jail time, depending on factors like BAC level and prior offenses. Our Flagstaff DUI lawyers will explain the specific consequences you may face.

Challenging BAC Evidence in Court

Blood alcohol testing isn’t infallible. Police officers and testing facilities must follow strict protocols for administering tests and handling evidence. Failure to adhere to these procedures cast doubt on the accuracy and admissibility of results. Some common issues your Griffen & Stevens legal team might raise to challenge BAC evidence include the following. 

Calibration and Maintenance

Regular maintenance and calibration of breath testing equipment are essential to ensure accurate results. If records show the device was overdue for service or had a history of malfunctions, BAC readings may be deemed unreliable.

Influence of Medical Conditions

Certain issues affect the accuracy of breath tests. For example, gastroesophageal reflux disease (GERD) can cause stomach alcohol to be released into the mouth, while diabetes can produce acetones that some breathalyzers mistake for alcohol. Our DUI lawyers may find it helpful to use this type of medical evidence to contest BAC results.

Lack of Probable Cause

Police must have a valid reason to pull you over and conduct a DUI investigation. If the officer lacked probable cause or reasonable suspicion, any evidence collected during the stop, including BAC tests, may be suppressed.

Violation of Implied Consent

Under Arizona's implied consent laws, drivers are required to submit to chemical testing if arrested for DUI. However, officers must inform drivers of the consequences of refusing a test. If proper warnings weren’t given, the refusal may not be admissible in court.

Missing or Incomplete Chain of Custody

Accurate documentation of a blood sample's journey from collection to testing is crucial to ensure its integrity. If gaps or discrepancies exist in the chain of custody paperwork, our lawyer can argue the evidence is unreliable.

Validity of Kits

Blood testing kits have expiration dates and specific storage requirements to maintain their accuracy. Using expired kits or failing to store them correctly can lead to incorrect BAC results that we might challenge.

Failure to Advise 

In Arizona, you have the right to obtain an independent blood alcohol test in addition to any tests administered by law enforcement. If the arresting officer failed to inform you of this right, it may provide grounds to contest the state's evidence.

Rely on the Experience of Our Flagstaff DUI Lawyers in BAC Testing Cases

Building a strong defense against DUI charges requires carefully analyzing every aspect of the case, including the BAC testing methods and results. You need representation you can trust who knows exactly what to look for and how to effectively challenge questionable evidence. 

Griffen & Stevens Law Firm, PLLC is rated “Best Law Firms – Tier 1” by U.S. News & World Report due to our professional reputation, trial results, and successful resolution of thousands of cases for clients throughout Northern Arizona. We understand the science behind blood alcohol testing, and won’t hesitate to turn to expert witnesses—such as toxicologists or forensic specialists—to provide testimony supporting the defense's arguments.

At the end of the day, having our dedicated DUI legal team by your side can completely change the trajectory of your case. Our expertise, combined with an unwavering commitment to protecting your rights, gives you the strongest possible defense.