The Science Behind Breathalyzer Tests in Arizona: Accuracy and Controversies

The concept of a breathalyzer test – a test that can measure intoxication levels by analyzing blood alcohol content – has been around since the 1920s. The first iteration of a breathalyzer device, the “Drunkometer,” was introduced in 1954. Since then, breathalyzers have undergone significant changes due to advances in technology. However, they have always been the subject of controversy due to questions of accuracy.


What Is a Breathalyzer Test? 

A breathalyzer is a machine that measures the amount of ethanol in a person’s body by testing his or her breath. It is a portable device that a driver can blow into during a traffic stop. It analyzes the amount of alcohol in the breath sample and displays a test result within seconds. 

If the driver blows over the legal limit of 0.08 percent blood alcohol content (BAC), he or she can be arrested for “DUI per se,” or driving under the influence without any other evidence of intoxication needed.

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How Does a Breathalyzer Test Work? 

When alcohol is consumed, the body absorbs it into the bloodstream through the lining of the stomach. As blood passes through the lungs, some of the alcohol evaporates and enters the lungs. The concentration of alcohol detected in the lungs is indicative of the concentration of alcohol in the blood. This allows law enforcement officers to determine a driver’s BAC using a breath sample.

A breathalyzer test is able to measure a driver’s BAC due to a chemical reaction that occurs within the device. The alcohol present in an individual’s breath will react with a solution called potassium dichromate. When alcohol is present, this normally orange solution will turn green. This color change creates an electrical current that the breathalyzer can convert into a value. 


How Accurate Are Breathalyzer Tests?

The accuracy of breathalyzer tests has been called into question since the advent of this device. This is because many different factors outside of alcohol consumption can affect a breathalyzer test’s results. Examples include: 

  • The individual’s temperature
  • Sex (male or female)
  • Body composition
  • Health status or medical conditions
  • Stomach contents
  • Other compounds detected in the breath
  • The volume of air the individual exhales
  • Human error during the administration of the test

Law enforcement must properly calibrate their breathalyzer devices and keep them adequately maintained. The officer must be trained in how to correctly administer the test, including a mandatory observation period of at least 15 minutes to ensure no foreign material is in the driver’s mouth. If the law enforcement officer who administers the breathalyzer test skips a step or makes a mistake, the results of the test may be inaccurate.

Can You Argue Against Breathalyzer Evidence in a DUI Case? 

Due to the large number of factors that can affect a breathalyzer test and the wide margin for error, the accuracy of these tests is often questioned in DUI cases in Arizona. A DUI defense attorney may point out the weaknesses of breathalyzer tests and provide evidence showcasing why the results are unreliable and should not be admissible in court. 

From user errors and device malfunctions to physiological and environmental variables, there are many potential reasons to question the accuracy of a breathalyzer test. If you have been arrested for allegedly driving under the influence after taking a breathalyzer test in Arizona, contact a criminal defense lawyer at the Law Offices of John Phebus for a free case review.

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If you would like to discuss options on your case and how we can provide legal help, contact The Law Offices of John Phebus Glendale Criminal and Personal Injury Lawyer today and connect with one of our highly experienced Scottsdale criminal defense attorneys.

John Allen Phebus – Experienced Personal Injury & Criminal Defense Attorney

John Phebus is a seasoned attorney specializing in personal injury and criminal defense law. With a focus on DUI defense, vehicular crimes, and serious injury cases, John has been fiercely advocating for his clients, ensuring they receive the representation and compensation they deserve. His expertise and dedication have led to numerous successful outcomes. If you’re seeking a knowledgeable and passionate attorney who will fight for your rights, John Phebus is here to help.

Years of experience: +30 years

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