The Reliability of Breathalyzer Devices in DUI Cases: A Comparative Analysis Across States

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Breathalyzer devices play a crucial role in the enforcement of DUI (driving under the influence) laws across the United States. These devices estimate blood alcohol content (BAC) by analyzing a person’s breath and are often used as evidence in DUI cases. However, questions about the reliability of breathalyzers have persisted, and recent investigations have brought these concerns to the forefront.

As a Rhode Island-based DUI attorney, I have provided a detailed examination of the reliability of breathalyzer devices in a few states, offering a comparative analysis to provide a more comprehensive understanding of this important issue.



New York

In New York, breathalyzers continue to be commonly used as evidence in DWI (driving while intoxicated) and DUI cases. However, challenges to the admissibility of breathalyzer results have occurred, and in some cases, defense attorneys have successfully argued that the breath test should be inadmissible. Despite these challenges, there are instances where New York judges have allowed breathalyzer evidence to be used. The state has made progress by establishing a clear precedent for determining the admissibility of breath tests, moving away from placing absolute trust in these devices and the law enforcement officers who operate them.


Florida is another state where breathalyzer tests are routinely used in DUI cases. However, the accuracy and reliability of these tests have been called into question. In particular, concerns about the calibration and maintenance of breathalyzer devices have led to legal challenges. According to Florida law, breathalyzers must be calibrated and inspected regularly to ensure their accuracy, and failure to do so can result in unreliable readings. When an improperly calibrated breathalyzer is used, it may lead to false or exaggerated BAC readings, potentially resulting in wrongful DUI charges.


California law enforcement agencies use two main types of breathalyzer devices: evidential breath test (EBT) devices and preliminary alcohol screening (PAS) devices. EBT devices are generally considered more reliable and are used at police stations, while PAS devices are portable and used at roadside checkpoints. Regardless of the type of device used, the accuracy of breathalyzer results in California can be affected by various factors, such as calibration errors, officer training, and the presence of interfering substances in the person’s breath. As a result, DUI defense attorneys often challenge the reliability of breathalyzer results in court.


PPC for Legal


Texas law requires that breathalyzer devices be calibrated regularly, and law enforcement agencies must maintain records of these calibrations. Additionally, the Texas Breath Alcohol Testing Program establishes standards and procedures for breath testing in the state, including training requirements for operators. Despite these regulations, issues of accuracy and reliability continue to arise. For instance, certain medical conditions and the use of certain products (e.g., mouthwash) can produce false positive results. Texas courts have seen cases where defendants have successfully challenged breathalyzer results based on improper calibration, operator error, and other factors.


In Washington State, the Dräger Alcotest 9510 breathalyzer machine has been the subject of controversy. A recent case in Kitsap County led to the exclusion of breath test results from this particular device, as the court ruled that it failed to produce accurate, precise, and reliable breath test results as required by state regulations. The ruling has implications for thousands of DUI cases in the state where the Dräger 9510 breathalyzer was used, calling into question the reliability of breathalyzer evidence in Washington’s legal system. The case also highlights the importance of proper calibration and adherence to scientifically approved methods for breath testing.


In Illinois, breathalyzer tests are frequently administered during DUI traffic stops. However, concerns about the accuracy and admissibility of breathalyzer results have emerged. Illinois law mandates that breathalyzer devices be calibrated and certified according to specific protocols. Defense attorneys in the state have successfully challenged the admissibility of breathalyzer results in cases where there was insufficient evidence of proper calibration or where other procedural errors occurred. Additionally, Illinois courts have recognized the potential for certain medical conditions, such as acid reflux or diabetes, to affect breathalyzer readings and produce falsely elevated BAC levels.


Colorado law requires that breathalyzer devices undergo regular inspection, calibration, and certification. However, the state has seen its share of legal challenges regarding the reliability of breathalyzer evidence. Defense attorneys in Colorado often scrutinize the records of accuracy checks, calibration, and maintenance to determine the reliability of breath test results. Additionally, the state recognizes the importance of observing a driver for a specific amount of time before administering a breath test to ensure that factors such as burping, vomiting, or the use of mouthwash do not affect the test results. Despite these precautions, the accuracy of breathalyzer tests remains a point of contention in DUI cases in Colorado.


Computer Forensics


Arizona has strict DUI laws, and breathalyzer tests play a significant role in the enforcement of these laws. However, the reliability of breathalyzer devices in Arizona DUI cases has come under scrutiny. Defense attorneys have raised concerns about potential sources of error, such as improper calibration, operator error, and the use of outdated devices. In some cases, breathalyzer results have been successfully challenged and excluded from evidence. Arizona law requires that breathalyzer devices be tested and certified to ensure accuracy, and the state has implemented protocols to enhance the reliability of breath test results.

Want to learn more? Check out my article examining the reliability of breathalyzer devices in Rhode Island, Massachusetts and Connecticut.

Overall, the reliability of breathalyzer devices in DUI cases is an issue that affects multiple states across the country. While breathalyzer tests remain a common tool in DUI enforcement, questions about their accuracy and reliability have led to legal challenges, scientific studies, and changes to testing protocols. As states continue to grapple with these challenges, it is important for both law enforcement and the legal system to ensure the accuracy and reliability of breathalyzer evidence in DUI cases.

While breathalyzer devices remain a widely used tool in the enforcement of DUI laws, concerns about their reliability persist across states. Legal challenges and scientific studies have highlighted issues with calibration, maintenance, and the potential for false readings. As a result, states have taken various approaches to address these concerns, including the establishment of standards and procedures for breath testing, as well as increased scrutiny of breathalyzer evidence in court. Ultimately, the reliability of breathalyzer devices in DUI cases is a complex issue that requires careful consideration of scientific, legal, and practical factors.

S. Joshua Macktaz

S. Joshua Macktaz, Esq. is a top-rated attorney in Rhode Island with 30 years of experience in DUI and criminal defense. As a former Rhode Island Special Assistant Attorney General from 1993-1997, Macktaz prosecuted hundreds of criminal cases and lectured police academy cadets on DUI investigations and prosecutions. Macktaz provides aggressive and personal representation to clients facing criminal charges in Rhode Island. He reviews and oversees cases, appearing in court with clients, and offering free consultations. Macktaz has received over 300 five-star ratings on Google, with testimonials attesting to his successful defense and expungement of criminal offenses.

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